DISEASES OF THE HORSE'S FOOT

ByH. CAULTON REEKS

Fellow of the Royal College of Veterinary SurgeonsAuthor of 'The Common Colics of the Horse'

1906

ToJ. MacQueen, F. R. C. V. S. , Professor of Surgery at the Royal Veterinary College, London, as a slightacknowledgment of his ability as a teacher, and in return for many kindlyservices, this volume is gratefully inscribed by

THE AUTHOR. 

PREFACE

Stimulated by the reception accorded my 'Common Colics of the Horse, ' bothin this country and in America, and assured by my publishers that a work ondiseases of the foot was needed, I have been led to give to the veterinaryprofession the present volume. 

While keeping the size of the book within reasonable limits, no efforthas been spared to render it as complete as possible. This has only beenachieved by adding to my own experience a great deal of the work of others. To mention individually those who have given me permission to use theirwritings would be too long a matter here. In every case, however, where thequotation is of any length, the source of my information is given, eitherin the text or in an accompanying footnote. A few there are who will, perhaps, find themselves quoted without my having first obtained theirpermission to do so. They, with the others, will, I am sure, accept myhearty thanks. 

The publishers have been generous in the matter of illustrations anddiagrams, and although to the older practitioner some of these may appearsuperfluous, it is hoped they will serve to render the work an acceptabletextbook for the student. 

H. CAULTON REEKS. 

SPALDING, _January, 1906_. 

CONTENTS

CHAPTER I

INTRODUCTION

CHAPTER II

REGIONAL ANATOMY

A. The BonesB. The LigamentsC. The TendonsD. The ArteriesE. The VeinsF. The NervesG. The Complementary Apparatus of the Os PedisH. The Keratogenous MembraneI. The Hoof

CHAPTER III

GENERAL PHYSIOLOGICAL AND ANATOMICAL OBSERVATIONS

A. Development of the HoofB. Chemical Properties and Histology of HornC. Expansion and Contraction of the HoofD. The Functions of the Lateral CartilagesE. Growth of the Hoof

CHAPTER IV

METHOD OF EXAMINING THE FOOT

CHAPTER V

GENERAL REMARKS ON OPERATIONS ON THE FOOT

A. Methods of RestraintB. Instruments requiredC. The Application of DressingsD. Plantar Neurectomy History of the Operation Preparation of the Subject The Operation After-treatmentE. Median NeurectomyF. Length of Rest after NeurectomyG. Sequelæ of Neurectomy Liability of Pricked Foot going undetected Loss of Tone in the Non-sensitive Area Gelatinous Degeneration Chronic Oedema of the Leg Persistent Pruritus Fracture of the Bones Neuroma Reunion of the Divided Nerve The Existence of an Adventitious Nerve-supply StumblingH. Advantages of the OperationI. The Use of the Horse that has undergone Neurectomy

CHAPTER VI

FAULTY CONFORMATION

A. Weak HeelsB. Contracted Foot (_a_) Contracted Heels (_b_) Local or Coronary ContractionC. Flat-footD. Pumiced-foot, Dropped Sole, or Convex SoleE. 'Ringed' or 'Ribbed' HoofF. The Hoof with Bad Horn (_a_) The Brittle Hoof (_b_) The Spongy HoofG. Club-FootH. The Crooked Foot (_a_) The Foot with Unequal Sides (_b_) The Curved Hoof

CHAPTER VII

DISEASES ARISING FROM FAULTY CONFORMATION

A. Sand-crack Definition Classification Causes Complications Treatment Surgical Shoeing for Sand-crack

B. Corns Definition Classification Causes Pathological Anatomy and Histology Treatment Surgical Shoeing for Corn

C. Chronic Bruised Sole

CHAPTER VIII

WOUNDS OF THE KERATOGENOUS MEMBRANE

A. Nail-bound Definition Causes Symptoms Treatment

B. Punctured Foot Definition Causes Common Situations of the Wound Classification Symptoms and Diagnosis Complications Prognosis Treatment

C. Coronitis (Simple)

 1. Acute Definition Causes Symptoms Complications Prognosis Treatment

 2. Chronic Definition Causes Symptoms Treatment

D. False Quarter Definition Causes Treatment

E. Accidental Tearing off of the Entire Hoof

CHAPTER IX

INFLAMMATORY AFFECTIONS OF THE KERATOGENOUS APPARATUS

A. ACUTE Acute Laminitis Definition Causes Symptoms Pathological Anatomy Complications Diagnosis and Prognosis Treatment Broad's Treatment for Laminitis Smith's Operation for Laminitis

B. CHRONIC

 1. Chronic Laminitis Definition Causes Symptoms Pathological Anatomy Treatment

 2. Seedy-Toe Definition Causes Symptoms Treatment

 3. Keraphyllocele Definition Causes Symptoms Treatment

 4. Keratoma

 5. Thrush Definition Causes Symptoms Treatment

 6. Canker Definition Causes, Predisposing and Exciting Symptoms and Pathological Anatomy Differential Diagnosis and Prognosis Treatment Malcolm's, Lieutenant Rose's, Bermbach's, Hoffmann's and Imminger's Treatment for Canker

 7. Specific Coronitis Definition Causes Symptoms Treatment

CHAPTER X

DISEASES OF THE LATERAL CARTILAGES

A. Wounds of the Cartilages

B. Quittor Definition Classification

 1. Simple or Cutaneous Quittor Definition Causes Symptoms Pathological Anatomy Prognosis Complications Treatment, Preventive and Curative

 2. Sub-horny Quittor Definition Causes Symptoms and Diagnosis Complications Necrosis of the Lateral Cartilage Pathological Anatomy of the Diseased Cartilage Necrosis of Tendon and of Ligament Ossification of the Cartilage Treatment Operations for Extirpation of the Cartilage

C. Ossification of the Lateral Cartilages (Side-bones) Definition Symptoms and Diagnosis Causes Treatment Smith's Operation for Ossification of the Lateral Cartilages

CHAPTER XI

DISEASES OF THE BONES

A. Periostitis and Ostitis 1. Periostitis (_a_) Simple Acute Periostitis (_b_) Suppurative Periostitis (_c_) Osteoplastic Periostitis

 2. Ostitis (_a_) Rarefying Ostitis (_b_) Osteoplastic Ostitis (_c_) Caries and Necrosis

Treatment of Periostitis

Recorded Cases of Periostitis

B. Pyramidal Disease, Buttress Foot, or Low Ringbone Definition Symptoms and Diagnosis Pathological Anatomy Treatment Recorded Cases of Buttress Foot

C. Fractures of the Bones 1. Fractures of the Os Coronæ Recorded Cases of Fractures of the Os Coronæ

 2. Fractures of the Os Pedis Recorded Cases of Fractures of the Os Pedis

 3. Fractures of the Navicular Bone Recorded Case of Fracture of the Navicular Bone

 Treatment of Fractures of the Bones of the Foot

CHAPTER XII

DISEASES OF THE JOINTS

A. Synovitis (_a_) Simple (1) Acute (2) Chronic (_b_) Purulent or SuppurativeB. Arthritis (_a_) Simple or Serous (_b_) Acute (_c_) Purulent or Suppurative (_d_) Anchylosis

C. Navicular Disease Definition History Pathology Changes in the Bursa Changes in the Cartilage Changes in the Tendon Changes in the Bone Causes Heredity Compression Concussion A Weak Navicular Bone An Irregular Blood-supply to the Bone Senile Decay Symptoms and Diagnosis Differential Diagnosis Prognosis Treatment

D. Dislocations

LIST OF ILLUSTRATIONS

1. The Bones of the Phalanx2. The Os Coronæ (Anterior View)3. The Os Coronæ (Posterior View)4. The Os Pedis (Postero-lateral View)5. The Os Pedis (viewed from Below)6. The Navicular Bone (viewed from Below)7. The Navicular Bone (viewed from Above)8. Ligaments of the First and Second Interphalangeal Articulations (Lateral View). (_After Dollar and Wheatley_)9. Ligaments of the First and Second Interphalangeal Articulations (viewed from Behind). (_After Dollar and Wheatley_)10. The Flexor Tendons and the Extensor Pedis. (_After Haübner_)11. The Flexor Perforans and Perforatus12. The Flexor Perforans and Perforatus (the Perforans cut through and deflected)13. Median Section of Normal Foot14. The Arteries of the Foot15. The Veins and Nerves of the Foot16. The Lateral Cartilage17. The Keratogenous Membrane (viewed from the Side)18. The Keratogenous Membrane (viewed from Below)19. The Wall of the Hoof20. Internal Features of the Hoof21. Inferior Aspect of the Hoof22. Hoof with the Sensitive Structures removed23. Section of Epidermis24. Section of Skin with Hair Follicle and Hair25. Section of Human Nail and Nail-bed26. Section of Foot of Equine Foetus. (_Mettam_)27. Section from Foot of Sheep Embryo. (_Mettam_)28. Section from Foot of Calf Embryo. (_Mettam_)29. Section from Foot of Equine Foetus. (_Mettam_)30. Section through Hoof and Soft Tissues of a Foal at Term. (_Mettam_)31. Perpendicular Section of Horn of Wall32. Horizontal Section of Horn of Wall33. Horizontal Section through the Junction of the Wall with the Sole34. Section of Frog. (_Mettam_)35. Professor Lungwitz's Apparatus for Examining the Foot Movements36. Professor Lungwitz's Apparatus for Examining the Foot Movements37. The Movements of the Solar and Coronary Edges of the Hoof illustrated. (_Lungwitz_)38. The Blind39. The Side-line40. Method of securing the Hind-foot with the Side-line41. The Hind-foot secured with the Side-line42. The Casting Hobbles43. Method of securing the Hind-leg upon the Fore44. The Hind-leg secured upon the Fore45. The Drawing-knife (Ordinary Pattern)46. Modern Forms of Drawing-knives47. Symes's Knife48-51. Illustrating Colonel Nunn's Method of applying a Poultice to the Foot52. Poultice-boot of Canvas and Steel53. Poultice-boot of Cocoa-fibre54. Foot-swab55. The Shoe with Plates56. Quittor Syringe57. The Esmarch Bandage and Tourniquet58. Tourniquet with Wooden Block59. Neurectomy Bistoury60. Neurectomy Needle61. Double Neurectomy Tenaculum62. Adventitious Nerve-supply to Foot. (_Sessions_)63. Tip Shoe64. The Tip Shoe 'let in' to the Foot65. The Thinned Tip66. Drawing-knife for Charlier Shoeing67. The Foot prepared for the Charlier Shoe68. Bar Shoe69. Rubber Bar Pad on Leather70. The Bar Pad applied with a Half-shoe71. Frog Pad72. Frog Pad applied73. Smith's Expansion Shoe for Contracted Feet74. A Contracted Foot treated with Smith's Shoe75. De Fay's Vice76. Hartmann's Expanding Shoe77. Broué's Slipper Shoe. (_Gutenacker_)78. Einsiedel's Slipper and Bar-clip Shoe. (_Gutenacker_)79. Hoof showing Coronary Contraction. (_Gutenacker_)80. Flat-foot (Solar Surface). (_Gutenacker_)81. Hoof showing Laminitis Rings on the Wall. _(Gutenacker)_82. Hoof showing 'Grass' Rings on the Wall. (_Gutenacker_)83. Club-foot. (_Gutenacker_)84. Shoe with extended Toe-piece. (_Gutenacker_)85. A Crooked Foot in Cross-section. (_Gutenacker_)86. Sand-crack Firing-iron87. Sand-crack Forceps and Clamp. (_Vachette's_)88. McGill's Sand-crack Clamp89. Koster's Sand-crack Clamp90. Sand-crack Belt91. Method of 'Easing' the Bearing of the Wall on the Shoe in the Treatment of Sand-crack92. Method of 'Easing' the Bearing of the Wall on the Shoe in the Treatment of Sand-crack93. Method of 'Easing' the Bearing of the Wall on the Shoe in the Treatment of Sand-crack94 96. Grooving the Wall in the Treatment of Sand-crack97. Removing the Wall in the Treatment of Sand-crack98. Removing the Wall in the Treatment of Sand-crack99. Horizontal Section of Corn. (_Gutenacker_)100. Inner Surface of the Wall, showing Changes in Chronic Corn. (_Gutenacker_)101. Perpendicular Section of the Wall in a Case of Chronic Corn. (_Gutenacker_)102. Three-quarter Shoe103. Three-quarter Bar Shoe104. Shoe with a 'Dropped' Heel105. Shoe with a 'Set' Heel106. Curette, or Volkmann's Spoon107. Resection of the Terminal Portion of the Perforans Tendon (_Gutenacker_)108. Shoe with extended Toe-piece. (_Colonel Nunn_)109. Mesian Section of Foot with Lesions following Coronitis. (_Gutenacker_)110. Toe of Ordinary Hind-shoe111. Toe of Hind-shoe Bevelled for the Prevention of Overreach112. Hoof showing Lesion in the Wall following Coronitis. (_Gutenacker_)113. Foot with Lesions of Chronic Coronitis. (_Gutenacker_)114. Hoof Accidentally Tom from Foot. (_Cartledge_)115. Hoof Accidentally Tom from Foot. (_Rogerson_)116. Section of Foot with Laminitis of Eight Days' Duration. (_Gutenacker_)117. Section of Foot with Laminitis of Fourteen Days' Duration. (_Gutenacker_)118. Chronic Ostitis of the Os Pedis in Laminitis. 119. Broad's Rocker Bar Shoe for Laminitis. 120. The Foot showing Grooves made in the Wall for Treatment of Laminitis (Anterior Surface). 121. The Foot showing Grooves made for the Treatment of Laminitis (Solar Surface). 122. Foot with Chronic Laminitis. (_Gutenacker_)123. Inferior Aspect of Foot with Chronic Laminitis. (_Gutenacker_)124. Section of Foot with Laminitis of Three Weeks' Duration. (_Gutenacker_)125. Section of Foot with Laminitis of Several Years' Duration. (_Gutenacker_)126. Diagram showing Position of the Abnormal Growth of Horn in Chronic Laminitis. 127. Diagram showing the same Abnormal Growth of Horn Removed prior to Shoeing. 128. Shoe with Heel-clip. 129. Internal Seedy-Toe. 130. External Seedy-Toe. (_Colonel Nunn_)131. External Seedy-Toe. (_Colonel Nunn_)132. A Keraphyllocele on the Inner Surface of the Horn of the Wall at theToe. (_Gutenacker_)133. Os Pedis showing Absorption of Bone caused by the Pressure of a Keraphyllocele. (_Gutenacker_)134. Foot with Canker of the Frog and Heels. (_Gutenacker_)135. Foot with Canker extending to the Wall. (_Malcolm_)136. Foot with Advanced Canker. (_Gutenacker_)137. Feet affected with Specific Coronitis. (_Taylor_)138. Fore-foot with Specific Coronitis. (_Taylor_)139. Excision of the Lateral Cartilage (Old Method). (_Gutenacker_)140. Excision of the Lateral Cartilage. (_After Moller and Frick_). (_Gutenacker_)141. Excision of the Lateral Cartilage. (_After Bayer_. ) (_Gutenacker_)142. Partial Excision of the Lateral Cartilage143. Ossified Lateral Cartilages, or Side-bones. 144. Smith's Side-bone Saw (Old Pattern). 145. Smith's Side-bone Saw (Improved Pattern). 146. Smith's Hoof Plane. 147. Hodder's Hoof Chisel. 148. Foot showing the Grooves made in Smith's Operation for Side-bones (viewed from the Side). 149. Foot showing the Grooves made in Smith's Operation for Side-bones (viewed from Below). 150. Periostitis involving the Pedal and Navicular Bones. (_Litt_)151. Periostitis involving the Pedal and Navicular Bones. (_Litt_)152. Effects of Periostitis on the Os Pedis. (_Smith_)153. Effects of Periostitis on the Os Pedis. (_Smith_)154. Effects of Periostitis on the Os Pedis. (_Jones_)155. Effects of Periostitis on the Os Pedis. (_Jones_)156. Case of Buttress Foot. (_Routledge_)157. Foot showing Fracture of the Pyramidal Process in a Case of Buttress Foot. (_Routledge_)158. Fracture of the Os Coronæ. (_Crawford_)159. Fracture of the Os Coronæ. (_Crawford_)160. Fractured Os Pedis. (_Freeman_)161. Navicular Bone showing Lesions of Navicular Disease. (_Gutenacker_)162. Foot with the Seat of Navicular Disease exposed (showing Lesions). (_Gutenacker_)163. Navicular Bone showing Lesions of Navicular Disease (a Case of Long-standing). (_Gutenacker_)164. Frog Seton Needle. 165. Diagram showing Course of the Needle in Setoning the Frog. 

DISEASES OF THE HORSE'S FOOT

CHAPTER I

INTRODUCTION

The importance of that branch of veterinary surgery dealing with diseasesof the horse's foot can hardly be overestimated. That the animal'susefulness is dependent upon his possession of four good feet is a factthat has long been recognised. Who, indeed, is there to be found entirelyunacquainted with one or other of such well-known aphorisms as: 'Whoeverhath charge of a horse's foot has the care of his whole body'; 'As well ahorse with no head as a horse with no foot'; or the perhaps better known, and certainly more epigrammatic, 'No foot, no horse. '

Without taking these sayings literally, it will be admitted by almosteveryone that they contain a vast amount of actual truth. This allowed, itat once becomes clear that a ready understanding of the diseases to whichthe foot is liable, the means of holding them in check, and the correctmethods of treating them should figure largely in the knowledge at thecommand of the veterinary surgeon. 

In the very great majority of instances the horse's ability to performlabour is the one thing that justifies his existence, and to that end thepresence of four good, sound feet is an almost indispensable qualification. And yet how many circumstances do we see tending to militate against thatone essential. 

Even in colthood the foot, if neglected, may become a source of trouble. Unless periodically examined and properly trimmed, its shape is liable toserious alteration. From that in which it is best calculated to withstandthe effects of the wear it will be called upon to endure in after life, itmay become so changed for the worse as to seriously affect the animal'svalue. 

In the matter of feeding, too, trouble is likely to ensue. Particularly isthis the case where the colt shows points of exceptional merit. He is 'gotup' for show, and the feet are likely to fall victims to the mismanagementthat frequent exhibition so often carries with it. An extra allowance ofpeas, beans, wheat, or other equally injurious food is given. The result isa severe attack of laminitis, and an otherwise valuable and promising coltis permanently ruined. 

Exposed as it is, too, to injury, the foot of a young horse, even at grass, is frequently the seat of injuries from picked up nails, stakes, or otheragents which, unless detected and carefully treated, may terminate in atroublesome case of quittor and incurable lameness. 

With the passing of colthood, and the coming into effect of the evils offurther domestication, the troubles to which the foot is open become morenumerous. Foremost among them will come those having their starting-pointin errors of practice originating in the forge; for, in spite of attemptsat their education, smiths, as a class, are as yet grievously unversed ineven the elementary knowledge of the delicate construction of the memberthat is entrusted to their care. 

This fact has been dilated on in books devoted to shoeing, and in theprefatory note to the last edition of Fleming's manual on this subject wefind the following statement: 'The records of all humane societies showthat, of prosecutions for cruelty to animals, an overwhelming majorityrefer to the horse; and of these, a large proportion are for working horseswhile suffering from lameness in one form or other. 

'So frequent are such cases that observers have concluded that theirprevalence must result from some specific cause, and, not unnaturally, attention has thus been directed to the various modes of managementpractised in relation to the horse's foot, to the manner of shoeing, and, in particular, to the way in which the foot is prepared for the shoe. '

It must be remembered, however, that although harm in the forge mayfrequently arise from culpable roughness or carelessness, such is notnecessarily always the case, and that quite as much injury may result fromcareful and conscientious workmanship when it is unfortunate enough to bebased upon principles wrong in themselves to commence with. 

It so happens, too, that shoeing, in itself a necessary evil, may beresponsible for injuries in the causation of which the smith can haveplayed no part. Take, for example, the ill effects following upon theanimal's attendant allowing him to carry his shoes for too long a time. In this case the natural growth of the horn carries the heel of the shoefurther beneath the foot than is safe for a correct bearing; in fact, anterior to the point of inflection of the wall. The shoe, at the sametime, is greatly thinned from excessive wear. Result, a sharp andeasily-bended piece of iron situate immediately under the seat of corn. Pressure or actual cutting of the sole is bound to occur, and the animal islamed. 

Again, apart from the question of negligence or otherwise on the part ofthe smith or the animal's attendant, it must be remembered that the nailingon to the foot of a plate of iron is not giving to the animal an easiermeans of progression. The reverse is the case. In place of the sucker-likeface of the natural horn is substituted a smooth, and, with wear, highly-polished surface. Slipping and sliding attempts to gain a footholdbecome frequent, and strains of the tendons and ligaments follow in theirwake. 

As, however, this treatise is not intended to deal with the art of shoeing, the reader must be referred to other works for further information. Inaddition to Fleming's, there may be mentioned, among others, Hunting's 'Artof Horse Shoeing, ' and the very excellent volume of Messrs. Dollar andWheatley on the same subject. Leaving the forge, we may next look to thenature of the animal's work, and the conditions under which he is kept, foractive causes in the production of disorders of the foot. From the yieldingsoftness of the pasture he is called to spend the bulk of his time upon thehard macadamized tracks of our country roads, or the still more hard andmore dangerous asphalt pavings or granite sets of our towns. The former, with the bruises they will give the sole and frog from loose and scatteredstones, and the latter, with the increased concussion they will entail onthe limb, are active factors in the troubles with which we are about todeal. Upon these unyielding surfaces the horse is called to carry slowly orrapidly, as the case may be, not only his own weight, but, in addition, isasked to labour at the hauling of heavy loads. The effects of concussionand heavy traction combined are bound primarily to find the feet, and suchdiseases as side-bones, ringbones, corns, and sand-cracks commence to maketheir appearance. 

Again, as opposed to the comparative healthiness of the surroundings whenat grass, consideration must be given to the chemical changes the foot isfrequently subjected to when the animal is housed. 

Only too often the bedding the animal has to stand upon for several hoursof the twenty-four can only be fitly described as 'filthy in the extreme. 'The ammoniacal exhalations from these collected body-discharges must, anddo, have a prejudicial effect upon the nature of the horn, and, though slowin its progress, mischief is bound sooner or later to occur in the shape ofa weakened and discharging frog, with its concomitant of contracted heels. Lucky it is in such a case if canker does not follow on. 

Observers, too, have chronicled the occurrence in horse's feet of diseaseresulting from the use of moss litter. Tenderness in the foot is firstnoticeable, which tenderness is afterwards followed by a peculiar softeningof the horn of the sole and the frog. What should be a dense, fairlyresilient substance is transformed into a material affording a yieldingsensation to the fingers not unlike that imparted by a soft indiarubber, and as easily sliced as cheese-rind. 

Lastly, though the foot is extremely liable to suffer from the effectsof extreme dryness or excessive humidity, especially with regard to thechanges thus brought about in the nature of the horn, it is perforceexposed at all times to the varying condition of the roads upon which itmust travel. The intense dryness of summer and the constant damp of winter, each in their turn take part in the deteriorating influences at work uponit. 

Though this subject might be indefinitely prolonged, this brief résumé ofthe adverse circumstances to which the foot of the horse is exposedis sufficient to point out the extreme importance of its study to theveterinary surgeon. So long as the horse is used as a beast of burden solong will this branch of veterinary surgery offer a wide and remunerativefield of labour. 

CHAPTER II

REGIONAL ANATOMY

Considered from a zoological standpoint, the foot of the horse will includeall those parts from the knee and hock downwards. For the purposes of thistreatise, however, the word foot will be used in its more popular sense, and will refer solely to those portions of the digit contained withinthe hoof. When, in this chapter on regional anatomy, or elsewhere, thedescriptive matter or the illustrations exceed that limit, it will be withthe object of observing the relationship between the parts we are concernedwith and adjoining structures. 

Taking the limit we have set, and enumerating the parts within the hooffrom within outwards, we find them as follows:

A. THE BONES. --The lower portion of the second phalanx or os coronæ; thethird phalanx, os pedis, or coffin bone; and the navicular or shuttle bone. 

B. THE LIGAMENTS. --The ligaments binding the articulation. 

C. THE TENDONS. --The terminal portions of the extensor pedis and the flexorperforans. 

D. THE ARTERIES. 

E. THE VEINS. 

F. THE NERVES. 

G. THE COMPLEMENTARY APPARATUS OF THE OS PEDIS. 

H. THE KERATOGENOUS MEMBRANE. 

I. THE HOOF. 

A. THE BONES. 

THE SECOND PHALANX, OS CORONÆ, OR SMALL PASTERN BONE. --This belongs tothe class of small bones, in that it possesses no medullary canal. It issituated obliquely in the digit, running from above downwards and frombehind to before, and articulating superiorly with the first phalanx or ossuffraginis, and inferiorly with the third phalanx and the navicular bone. 

[Illustration: FIG. 1. --THE BONES OF THE PHALANX. 1, The os suffraginis; 2, the os coronæ; 3, the os pedis; 4, the navicular bone, hidden by the wingof the os pedis, is in articulation in the position indicated by the barbedline. ]

[Illustration: FIG. 2. --SECOND PHALANX OR OS CORONÆ (ANTERIOR VIEW). 1, Anterior surface; 2, superior articulatory surface; 3, inferiorarticulatory surface; 4, pits for ligamentous attachment. ]

[Illustration: FIG. 3. --SECOND PHALANX OR OS CORONÆ (POSTERIOR VIEW). 1, Posterior surface; 2, gliding surface for passage of flexor perforans; 3, lower articulatory surface. ]

Cubical in shape, it is flattened from before to behind, and may bedescribed as possessing six surfaces: _An anterior surface_, covered withslight imprints; _a posterior surface_, provided above with a transverselyelongated gliding surface for the passage of the flexor perforans; _twolateral surfaces_, each rough and perforated by foraminæ, and each bearingon its lower portion a thumb-like imprint for ligamentous attachment, andfor the insertion of the bifid extremity of the perforatus tendon; _asuperior surface_, bearing two shallow articular cavities, separated by anantero-posterior ridge, for the accommodation of the lower articulatingsurface of the first phalanx; _an inferior surface_, also articulatory, which in shape is obverse to the superior, bearing two unequal condyles, separated by an ill-defined antero-posterior groove, which surfacearticulates with the os pedis and the navicular bone. 

_Development_. --The bone usually ossifies from one centre, but often thereis a complementary nucleus for the upper surface. 

THE THIRD PHALANX, OS PEDIS, OR COFFIN BONE. --This also belongs to theclass of short bones. It forms the termination of the digit, and, with thenavicular bone, is included entirely within the hoof. For our examinationit offers _three surfaces_, _two lateral angles_, and _three edges_. 

_The Anterior or Laminal Surface_, following closely in contour the wall ofthe hoof, is markedly convex from side to side, nearly straight from aboveto below, and closely dotted with foraminæ of varying sizes. On each sideof this surface is to be seen a distinct groove, the _preplantar groove_, or _preplantar fissure_, which, commencing behind, between the basilar andretrossal processes, runs horizontally forwards from the angles or wings ofthe bone, and terminates anteriorly in one of the larger foraminæ. As thename 'laminal' indicates, it is this surface which in the fresh state iscovered by the sensitive laminæ. 

_The Inferior or Plantar Surface_, hollowed in the form of a low arch, presents for our inspection two regions, an anterior and a posterior, divided by a well-marked line, the _Semilunar Crest_, which extends forwardin the shape of a semicircle. The anterior region, as is the laminalsurface, is covered with foraminæ; in this case more minute. In the recentstate it is covered by the sensitive sole. The posterior region, lyingimmediately behind the semilunar crest, shows on each side of a medianprocess a large foramen, the _Plantar Foramen_. From this foramen runs the_Plantar Groove_, a channel, bounded above by the superior edge, and belowby the semilunar crest of the bone, which conducts the plantar arteriesinto the _Semilunar Sinus_, a well-marked cavity in the interior of thebone. 

_The Superior or Articular Surface_ consists of two shallow depressions, divided by a slight median ridge. Its posterior part shows a transverselyelongated facet for articulation with the navicular bone. 

_The Superior Edge_, outlining the superior margin of the laminal surface, describes a curve, with the convexity of the curve forward. In the centreof the curve is a triangular process, the _Pyramidal Process_, which servesas the point of attachment of the extensor pedis. 

_The Inferior Edge_, the most extensive of the three, separates the laminalfrom the solar surface. It is semicircular in shape, sharp, and finelydentated, and is perforated by eight to ten large foraminæ. 

_The Posterior Edge_, very slightly concave, divides the small, transversely elongated facet of the superior surface from the posteriorregion of the inferior surface. 

_The Lateral Angles_ of the bone, also termed the _Wings_, are twoprojections directed backwards. Each is divided by a cleft into an upper, the _Basilar Process_, and a lower, the _Retrossal Process_. In old animalsthe posterior portion of the cleft separating the two processes graduallybecomes filled in with bony deposit, thus transforming the cleft into aforamen, which gives passage to the preplantar artery. We may mentionin passing that the lateral angles give attachment to the lateralfibro-cartilages, and that the lateral angles themselves in old horsesbecome increased in size owing to ossification of portions of the adjacentlateral cartilages. 

_Development_. --The os pedis ossifies from two centres, one of which is forthe articular surface; but this epiphysis fuses with the rest of the bonebefore birth. 

[Illustration: FIG. 4. --THIRD PHALANX OR OS PEDIS (POSTERO-LATERAL VIEW). 1, Anterior or laminal surface; 2, preplantar foramen; 3, preplantargroove; 4, basilar process of the wing; 5, retrossal process of the wing;6, foramen caused by the ossifying together posteriorly of the basilar andretrossal processes. ]

[Illustration: FIG. 5. --THIRD PHALANX OR OS PEDIS (VIEWED FROM BELOW). 1, Plantar surface; 2, plantar foramen and plantar groove; 3, semilunar crest;4, tendinous surface; 5, retrossal processes of the wings. ]

THE NAVICULAR BONE, SHUTTLE BONE, OR SMALL SESAMOID. --Placed behindthe articulating point of the second and third phalanges, this smallshuttle-shaped bone assists in the formation of the pedal articulation. Itis elongated transversely, flattened from above to below, and narrow at itsextremities. In it we see two surfaces, and two borders. 

_The Superior or Articular Surface_ of the bone, which may easily berecognised by its smoothness, is moulded upon the lower articular surfaceof the second phalanx, being convex in its middle, and concave on eitherside. 

_The Inferior or Tendinous Surface_ resembles the preceding in form, butis broader and less smooth. In the recent state it is covered withfibro-cartilage for the passage of the flexor perforans. 

_The Anterior Border_ possesses above a small transversely elongated facetfor articulation with the os pedis, and below a more extensive groovedportion, perforated by numerous foraminæ, affording attachment to theinterosseous ligaments of the articulation. 

_The Posterior Border_, thick in the middle, but thinner towards theextremities, is roughened for ligamentous attachment. 

_Development_. --The bone ossifies from a single centre. 

B. THE LIGAMENTS. 

THE ARTICULATION OF THE FIRST WITH THE SECOND PHALANX, OR THE PASTERNJOINT. --Adhering to the limit we have set, this articulation should notreceive our attention. As, however, we shall in a later page be concernedwith fractures of the os coronæ, which fractures may affect thearticulation above mentioned, a brief note of its formation will not be outof place. 

It is an imperfect hinge-joint, permitting of extension and flexion, allowing the first phalanx to pivot on the second, and admitting of theperformance of slight lateral movements. It is formed by the opposing ofthe inferior surface of the os suffraginis with the superior surface of theos coronæ. The articulating surface of the os coronæ is supplemented bythe addition behind of a thick piece of _fibro-cartilage (the glenoid_)attached inferiorly to the posterior edge of the upper articulatory surfaceof the os coronæ, and superiorly by means of three fibrous slips on eachside to the os suffraginis. The innermost of these three slips becomesattached to about the middle of the lateral edge of the suffraginis, andthe remaining two, beneath the first, attach themselves to nearer the lowerend of that bone. The posterior surface of the complementary cartilageforms a gliding surface for the passage of the perforans. 

[Illustration: FIG. 6. --THE NAVICULAR BONE (VIEWED FROM BELOW). 1, Inferiorsurface (smooth for the passage of the flexor perforans); 2, anterior edgeof inferior surface; 3, posterior edge of inferior surface. ]

[Illustration: FIG. 7. --THE NAVICULAR BONE (VIEWED FROM ABOVE, THE BONETILTED POSTERIORLY TO SHOW ITS ANTERIOR BORDER). 1, Superior articulatorysurface; 2, anterior border (grooved portion of); 3, anterior border(articulatory portion of). ]

[Illustration: FIG. 8. --LIGAMENTS OF THE FIRST AND SECOND INTERPHALANGEALARTICULATIONS (VIEWED FROM THE SIDE). (AFTER DOLLAR AND WHEATLEY. ) 1, Outermost slip from the glenoidal fibro-cartilage; 2, lateral ligament ofthe first interphalangeal articulation; 3, prolongations of the lateralligament of the first interphalangeal articulation attached to the end ofthe navicular bone to form the postero-lateral ligament of the pedal joint;4, end of the navicular bone; 5, antero-lateral ligament of the pedaljoint. ]

_The Lateral Ligaments_. --These are large and thick, an outer and an inner, running obliquely from above downwards and backwards. Each is insertedsuperiorly into the lateral tubercle of the lower end of the first phalanx, and inferiorly to the side of the second phalanx, their most inferiorfibres becoming finally fixed to the extremities of the navicular bone, where they form the postero-lateral ligaments of the pedal articulation. In front of the joint the extensor pedis plays the part of an additionalligament. 

_The Synovial Membrane_. --This is limited in front by the tendon of theextensor pedis, on each side by the lateral ligaments of the joint, andbehind by the glenoid fibro-cartilage. At this point it is prolongedupwards as a pouch behind the lower extremity of the first phalanx. 

THE ARTICULATION OF THE SECOND PHALANX WITH THE THIRD, THE PEDAL, OR THECOFFIN JOINT. --This also is an imperfect hinge-joint, permitting only offlexion and extension, which movements are more restricted than in theprevious articulation. Three bones enter into its formation: the secondphalanx, the third phalanx, and the navicular bone. The lower articulatorysurface is formed by the third phalanx and the navicular bone combined. To effect this the navicular is closely and firmly attached to the thirdphalanx by an interosseous ligament. The two bones, as one, are thenconnected to the second phalanx by four lateral ligaments, an anterior anda posterior on each side. 

_The Interosseous Ligament_ consists of extremely short fibres running fromthe extensively grooved portion of the anterior surface of the navicularbone to become attached to the os pedis immediately behind its articularsurface. 

_The Antero-lateral Ligaments_ are attached by their superior extremitiesto the lateral surfaces of the second phalanx, and by their inferiorextremities into the depressions on either side of the pyramidal process ofthe os pedis. 

_The Postero-lateral Ligaments_. --As mentioned when describing the firstinterphalangeal articulation, these are in reality continuations of thelateral ligaments of that joint. Running obliquely downwards and backwardsfrom their point of attachment to the first phalanx they curve round thelower part of the side of the second phalanx and end on the extremities andposterior surface of the navicular bone. Having reached that position, theysend short attachments to the retrossal process of the os pedis and to theinner face of the lateral cartilage. 

[Illustration: FIG. 9. --LIGAMENTS OF THE FIRST AND SECOND INTERPHALANGEALARTICULATIONS (VIEWED FROM BEHIND). (AFTER DOLLAR AND WHEATLEY. ) 1, Suspensory ligament; 2, innermost slip from complementary cartilage ofpastern joint; 3, middle slip from complementary cartilage of pasternjoint; 4, outermost slip from complementary cartilage of pastern joint; 5, glenoid or complementary cartilage of pastern joint; 6, postero-lateralligaments of the pedal joint; 7, the navicular bone; 8, interosseousligaments of the pedal joint; 9, semilunar crest of os pedis; 10, plantarsurface of os pedis. ]

_Synovial Membrane_. --This extends below the facets uniting the navicularto the pedal bone, and offers for consideration two sacs. A large oneposteriorly running up behind the second phalanx to nearly adjoin thesesamoidean bursæ, and a small one, a prolongation of the synovial membranebetween the antero-lateral and postero-lateral ligaments of the same side. This latter is often distended, and on account of its close proximity tothe seat of operation, is liable to be accidentally opened in excision ofthe lateral cartilage for quittor. 

C. THE TENDONS

In order to convey an intelligent understanding of the tendons it will bewise to briefly describe the course of their parent muscles from theircommencement. 

THE EXTENSOR PEDIS. --The extensor pedis arises from the lower extremityof the humerus in two distinct portions of unequal size, a muscular and atendinous. These are succeeded by two tendons passing in common through avertical groove at the lower end of the radius. Lower in the limb thesetendons separate, the outer and smaller joining the tendon of the extensorsuffraginis, and the inner and main tendon continuing its course downwards. With the exception of the navicular, it is attached to all the bones of thefoot, and is covered internally by the capsular ligaments of the jointsover which it passes, those with which we are concerned being the pasternjoint and the pedal joint. Before its attachment to the os pedis itreceives on each side of the middle of the first phalanx reinforcement inthe shape of a strong band descending obliquely over the fetlock from thesuspensory ligament. Widening out in fanlike fashion, it is inserted intothe pyramidal process of the os pedis. 

_Action_. --The action of this muscle is to extend the third phalanx on thesecond, the second on the first, and the first on the metacarpus. It alsoassists in the extension of the foot on the forearm. 

[Illustration: FIG. 10. --THE FLEXOR TENDONS AND EXTENSOR PEDIS. (AFTERHAÜBNER. ) 1, Tendon of flexor perforans; 2, its supporting check-band fromthe posterior ligament of the carpus; 3, tendon of the flexor perforatus;4, ring and sheath of the flexor perforatus; 5, widening out of the flexorperforatus to form the plantar aponeurosis; 6, suspensory ligament; 7, reinforcing band from the suspensory ligament to the extensor pedis; 8, theextensor pedis. ]

THE FLEXOR PEDIS PERFORATUS, OR THE SUPERFICIAL FLEXOR OF THEPHALANGES. --In common with the perforans, this muscle arises from the innercondyloid ridge of the humerus. It is reinforced at the lower end of theradius by the superior carpal ligament, passes through the carpal andmetacarpo-phalangeal sheaths, and, arriving behind the fetlock, forms aring for the passage of the flexor perforans. Its termination is bifid, andit is inserted on either side to the lateral surface of the second phalanx. 

[Illustration: FIG. 11. --THE FLEXOR PERFORANS AND FLEXOR PERFORATUSTENDONS. The metacarpo-phalangeal sheath and the ring of the perforatuslaid open posteriorly, and the cut edges reflected to show the passageof the perforans. 1, Reflected cut edges of the perforatus ring and themetacarpo-phalangeal sheath; 2, the perforans tendon; 3, point of insertionof the perforans tendon into the semilunar crest of the os pedis (thiswidened and thickened extremity of the perforans is known as the plantaraponeurosis). ]

[Illustration: FIG. 12. --THE FLEXOR PERFORATUS AND FLEXOR PERFORANSTENDONS. The metacarpo-phalangeal sheath and the ring of the perforatuslaid open posteriorly, and the cut edges reflected; the flexor perforanscut through at about the region of the sesamoids, and its inferior portiondeflected. 1, Superior end of severed perforans tendon; 2, inferior end ofsevered perforans tendon; 3, insertion of flexor perforans intosemilunar crest of os pedis; 4, the cut and reflected edges of themetacarpo-phalangeal sheath and perforatus ring; 5, the bifid insertion ofthe flexor perforatus into the lateral surfaces of the os corona; 6, the capsular ligament of the pedal joint; 7, the navicular bone; 8, theposterior surface and glenoid fibro-cartilage of the os coronæ. ]

_Action_. --This muscle flexes the second phalanx on the first, the first onthe metacarpus, and the entire foot on the forearm. Mechanically, itacts as a stay when the animal is standing by maintaining themetacarpo-phalangeal angle. 

[Illustration: FIG. 13. --MEDIAN SECTION OF FOOT. _A_, Os suffraginis; _B_, os coronæ; _C_, os pedis; _D_, navicular bone; _E_, tendon of the extensorpedis; _F_, insertion of the extensor pedis into the pyramidal process ofthe os pedis; _G_, the tendon of the flexor perforatus; _H_, insertion ofperforatus into the os coronæ; _I_, tendon of the flexor perforans; _J_, its passing attachment to the os coronæ; _K_, its final insertion into thesemilunar crest of os pedis; _a_, section of coronary cushion; _b_, sectionof plantar cushion; _c_, semilunar sinus of os pedis. ]

THE FLEXOR PEDIS PERFORANS, OR THE DEEP FLEXOR OF THE PHALANGES. --Thismuscle consists of three easily-divided portions: an ulnar, a humeral, anda radial, and has for points of origin the olecranon process of the ulna, the inner condyloid ridge of the humerus, and the posterior surface of theradius. These portions are continued by a common tendon which enters thecarpal sheath with the tendon of the perforatus, and continues with itthrough the synovial sheath of the metacarpo-phalangeal region. Like thelast-named tendon, it receives a supporting check-band, in this case fromthe posterior ligament of the carpus. Passing down between the suspensoryligament in front, and the perforatus tendon behind, it glides over thesesamoid pulley and passes through the ring formed by the perforatus. Continuing its course, it passes between the bifurcating portions of theextremity of the perforatus, glides over the smooth posterior surface ofthe supplementary glenoid cartilage of the articulation of the first andsecond phalanges, plays over the inferior surface of the navicular bone, and finally becomes inserted into the semilunar crest of the os pedis. Onreaching the posterior border of the navicular bone it widens out to formthe plantar aponeurosis. 

In connection with the lower portion of this tendon must be noticed theNavicular Sheath. This is a synovial sheath lining the deep face of thetendon, and reflected on to the navicular bone and the interosseousligament of the pedal joint. This will be of particular interest when wecome to deal with cases of pricked foot from picked up nails. Above, it isin connection with the synovial membrane of the pedal articulation and thatof the metacarpo-phalangeal sheath. 

_Action_. --The action of the perforans is to flex the third on the second, and the second on the first phalanx. The latter it flexes in turn on themetacarpus. It also assists in the flexion of the entire foot on theforearm, and in supporting the angle of the metacarpo-phalangealarticulation when the animal is standing. 

D. THE ARTERIES. 

So far as the arteries supplying the foot are concerned, we shall beinterested in following up the distribution of the two digitals, which arethe terminal branches of the Large Metacarpal. 

THE LARGE METACARPAL, OR COLLATERAL ARTERY OF THE CANNON. --This, the largerterminal branch of the posterior radial artery, needs brief mention, forthe reason that we shall be afterwards concerned with it in the operationof neurectomy. Its point of origin is the inside of the inferior extremityof the radius. Descending in company with the flexor tendons, and passingbehind the carpus and beneath the carpal sheath, it continues its descent, in company with the internal plantar nerve and the internal metacarpalvein, on the inner side of the flexor tendons until just above the fetlock. At this point it bifurcates into the digital arteries. 

From the carpus downwards the large metacarpal artery, the internalmetacarpal vein, and the internal plantar nerve are in close relation witheach other. The vein holds the anterior position. The artery is between thetwo, and has the nerve in close contact with it behind. 

THE DIGITAL ARTERIES, OR COLLATERAL ARTERIES OF THE DIGIT. --These are oflarge volume, and carry the blood to the keratogenous apparatus of thefoot. They separate from each other at an acute angle, and pass over theside of the fetlock, one to the inside, the other to the outside, to reachthe internal face of the basilar process of the os pedis, where theybifurcate to form the _Plantar_ and _Preplantar_ arteries. In the wholeof their course the digital arteries follow the flexor tendons, and arerelated in front to the digital vein, and behind to the posterior branch ofthe plantar nerve. This is the nerve implicated in the lower operation ofneurectomy, and its relation to adjoining structures will be detailedunder Section F. Of this chapter. During its course the digital arterygives off branches in the following positions:

1. _At the Fetlock_ numerous branches to the metacarpo-phalangealarticulation, the sesamoid sheath, and the tendons. 

2. _At the Upper Extremity of the First Phalanx_ branches for the supply ofthe surrounding tissues, and for the tissues of the ergot. 

3. _Towards the Middle of the Third Phalanx_, the _Perpendicular_ arteryof Percival. This arises at a right angle from the main vessel, andimmediately divides into two series of ramifications--an ascending anda descending. The ramifications of these series freely anastomose withcorresponding vessels of the opposite side. 

4. _At the Superior Border of the Lateral Cartilage_, the _Artery of thePlantar Cushion_. This is directed obliquely downwards and backwards, undercover of the cartilage, and is distributed to the middle portion of thecomplementary apparatus of the os pedis, as well as to the villous tissueand the coronet. A branch of it is turned forwards to join with thecoronary circle in forming the _circumflex artery of the coronet_. 

[Illustration: FIG. 14. --THE ARTERIES OF THE FOOT. The digital; 2, theperpendicular--(_a_) its ascending branch, (_b_) its descending branch;3, circumflex artery of coronary cushion; 4, the preplantar (ungual)artery--this is seen issuing from the preplantar foramen, and distributingnumerous ascending (_c_) and descending (_d_) branches (the latter concurin forming the circumflex artery of the toe); 5, the circumflex arteryof the toe; 6, at the point marked (*) the terminal branch of thedigital--namely, the plantar ungual--is hidden behind the lateralcartilage; 7, the lateral cartilage. ]

5. _Under the Lateral Cartilage_ two transverse branches, an anterior anda posterior, to form the _Coronary Circle_. The numerous ramificationsof these branches anastomose both anteriorly and posteriorly with theircorresponding branches of the artery of the opposite side. This circleclosely embraces the os coronæ. Among the larger branches given off fromits anterior portion are two descending, one on each side of the extensorpedis, to assist in the formation of the _Circumflex Artery of the CoronaryCushion_. The formation of this last-named artery is completed posteriorlyby the before-mentioned branch from the artery of the plantar cushion. 

THE PREPLANTAR (UNGUAL[A]) ARTERY. --This, the smaller of the two terminalbranches of the digital, is situated inside the basilar process of the ospedis. It turns round this to gain the fissure between the basilar andretrossal processes, and becomes lodged in the preplantar fissure. Hereit terminates in several divisions which bury themselves in the os pedis. Before leaving the inner aspect of the pedal wing it supplies a deep branchto the heel and the villous tissue. Gaining the outer aspect of thewing, it distributes a further backward branch, which passes behind thecircumflex artery of the pedal bone, and, during its passage in thepreplantar fissure, gives off ascending and descending branches, whichramify in the laminal tissue. 

THE PLANTAR (UNGUAL[A]) ARTERY. --This, the larger of the two terminalsof the digital, may be looked upon as a continuation of the main vessel. Running along the plantar groove, it gains the plantar foramen. Here itenters the interior of the bone (the semilunar sinus) and anastomoses withthe corresponding artery of the opposite side. The circle of vessels soformed is called the _Plantar Arch_ or the _Semilunar Anastomosis_. 

[Footnote A: The epithet 'ungual' is added by Chauveau to distinguishthese arteries from the properly so-called plantar arteries--the terminaldivisions of the posterior tibial artery. ]

From the semilunar anastomosis radiate two main groups of arterialbranches, an ascending group and a descending one. The _ascending_ branchespenetrate the substance of the os pedis, and emerge by the numerousforaminæ on its laminal surface. The _descending_ branches, larger in size, also penetrate the substance of the pedal bone, and emerge in turn fromthe foraminæ cribbling its outer surface--in this case the set of largerforaminæ opening on its inferior edge. Having gained exit from the bone, their frequent anastomosis, right and left, with their fellows forms alarge vessel following the contour of the inferior edge of the os pedis. This constitutes the _Circumflex Artery of the Toe_. 

E. THE VEINS. 

These commence at the foot with a series of plexuses, which may bedescribed as forming (1) AN INTERNAL OR INTRA-OSSEOUS VENOUS SYSTEM, and(2) AN EXTERNAL OR EXTRA-OSSEOUS VENOUS SYSTEM. 

1. THE INTRA-OSSEOUS VENOUS SYSTEM. --This is a venous system within thestructure of, and occupying the semilunar sinus of the os pedis. It followsin every respect the arrangement of the arteries as before described in thesame region. Efferent vessels emerge from the plantar foraminæ, follow theplantar fissures, and ascend within the basilar processes of the os pedis. Here they lie under shelter of the lateral cartilages, and assist in theformation of the deep layer of the coronary plexus of the extra-osseoussystem. 

2. THE EXTRA-OSSEOUS VENOUS SYSTEM. --This may be regarded as a close-meshednetwork enveloping the whole of the foot. Although a continuous system, itis best described by recognising in it three distinct parts:

 _(a) The Solar Plexus_. _(b) The Podophyllous Plexus_. _(c) The Coronary Plexus_. 

_(a) The Solar Plexus_. --The veins of this plexus discharge themselves intwo directions: (1) _By a central canal_ or canals running along the bottomof the lateral lacunæ of the plantar cushion to gain the deep layer of thecoronary plexus. (2) _By the Circumflex or Peripheral Vein of the Toe_, acanal formed by ramifications from the solar and the podophyllous plexuses, and following the direction of the artery of the same name. The circumflexvein terminates by forwarding branches to concur in the formation of thesuperficial coronary plexus. 

_(b) The Podophyllous or Laminal Plexus_. --The podophyllous veinsanastomose below with the circumflex vein of the solar plexus, and abovewith the veins of the coronary plexus. 

_(c) The Coronary Plexus_. --This proceeds from the podophyllous, theintra-osseous, and the solar networks, and consists of a _central_ and _twolateral parts_. 

The _central_ portion lies between the lateral cartilages and immediatelyunder the coronary cushion. The _lateral portions_ are ramifications onboth surfaces of the lateral cartilages. The ramifications on the lateralcartilages may be again distinguished as _superficial_ and _deep_. Thesuperficial layer is distributed over the external face of the cartilage, forming thereon a dense network, and finally converges towards the superiorlimit of the plexus to form ten or twelve principal branches, which againunite to form two large vessels. These vessels, by their final fusion atthe lower end of the first phalanx, constitute the digital vein. The deeplayer is formed, as before described, by ascending branches from theposterior parts of the podophyllous and solar plexuses, and by branchesfrom the intra-osseous system of the pedal bone. The veins of this deeplayer finally drain into the two vessels proceeding from the superficiallayer, which go to the formation of the digital vein. 

THE DIGITAL VEINS--These arise from the network formed on the surfaces ofthe lateral cartilages, and ascend in front of the digital arteries tounite above the fetlock, where they form an arch between the deep flexorand the suspensory ligament. From this arch (named the _Sesamoidean)_proceed the Metacarpal Veins. 

THE METACARPAL VEINS. --Three in number, they are distinguished as an_Internal_ and an _External Metacarpal_, and a _Deep_ or _InterosseousMetacarpal_. As we shall be concerned with these in the higher operation ofneurectomy, we may give them brief mention. 

THE INTERNAL METACARPAL VEIN, the largest of the three, has relationswith the internal metacarpal artery and the internal plantar nerve. Theserelations were shortly discussed under the section devoted to the arteries, to which the reader may refer. 

THE EXTERNAL METACARPAL VEIN. --This ascends on the external side of theflexor tendons in company with the external plantar nerve. 

_The Interosseous Vein_. --This is an irregular vessel running up betweenthe suspensory ligament and the posterior face of the large metacarpalbone. 

F. THE NERVES. 

THE PLANTAR NERVES. --These are two in number, and are distinguished asInternal and External. 

THE INTERNAL PLANTAR NERVE lies behind and in close contact with the greatmetacarpal artery during that vessel's course down the region of thecannon. A point of interest is that it gives off at about the middle ofthe cannon a branch which bends obliquely downwards and behind the flexortendons to join its fellow of the opposite side--namely, the externalplantar. This it joins an inch or more above the bottom of the splint bone. Measured in a straight line, this is about 2-1/2 inches below its pointof origin. Near the fetlock, at the level of the sesamoids, the internalplantar nerve ends in several digital branches. 

THE EXTERNAL PLANTAR NERVE. --This holds a position to the outside of themetacarpal region, analogous to that of the internal plantar nerve onthe inside of the limb, running down on the external edge of the flexortendons. Unlike the internal nerve, it is accompanied by a single vesselonly, the external metacarpal vein, behind which it lies. At the level ofthe sesamoid bones it divides, as does the _internal_ nerve, into threemain branches--the digital nerves. 

[Illustration: FIG. 15. --THE VEINS AND NERVES OF THE FOOT. 1, The digitalvein; 2, its main tributaries, draining the podophyllous plexus, andconcurring to form the digital; 3. The digital artery (the main trunk onlyof this is shown, in order to show its relationship with the vein andnerve); 4, the plantar nerve, with its three branches--(_a_) the anteriordigital, (_b_) the middle digital, (_c_) the posterior digital; 5, thepodophyllous plexus; 6, superficial portion of the coronary plexus; 7, theperipheral or circumflex vein of the toe. ]

THE DIGITAL NERVES. --These are distinguished as Anterior, Middle, andPosterior. 

_The Anterior Branch_ descends in front of the vein, distributing cutaneousbranches to the front of the digit, and terminating in the coronarycushion. 

_The Middle Branch_ descends between the artery and the vein, and freelyanastomoses with the two other branches. It terminates in the coronarycushion and the sensitive laminæ. 

_The Posterior Branch_. --This is the largest of the three, and may beregarded as the direct continuation of the plantar. At the fetlock it isplaced immediately above the digital artery, but afterwards takes up aposition directly behind that vessel. Together with the digital artery itdescends to near the basilar process of the os pedis. Here it passes withthe plantar artery into the interior of the os pedis, and continues itsmain branch, with the preplantar artery, in the fissure of the same name, to finally furnish supply to the os pedis and the sensitive laminæ. It isthis nerve which is divided in the low operation of neurectomy. 

Beyond the fact of this branch descending, in the region of the pastern, 1inch behind the digital artery, a further point of interest presents itselfto the surgeon, and one to which attention must be paid. This is thepresence in close proximity to the nerve of the Ligament of the Pad(Percival), or the Ligament of the Ergot (McFadyean). This is asubcutaneous glistening cord originating in the ergot of the fetlock, passing in an oblique direction downwards and forwards, and crossing overon its way both the digital artery and the posterior branch of the digitalnerve. 

In the foregoing description of the anatomy, we have taken the fore-limb asour guide. In the hind-limb, where they reach the foot, the counterparts ofthe tendons, arteries, veins, and nerves differ in no great essential fromtheir fellows in the fore. They will therefore need no special mention. 

G. THE COMPLEMENTARY APPARATUS OF THE OS PEDIS. 

This consists of two lateral pieces, the LATERAL CARTILAGES or_Fibro-cartilages_ of the pedal bone, united behind and below by the_Plantar Cushion_. 

1. THE LATERAL CARTILAGES. --Each is a flattened plate of cartilage, possessing two faces and four borders separated by four angles. 

The external face is convex, covered by a plexus of veins, and slightlyoverhangs the pedal bone. The internal face is concave, and covers infront the pedal articulation and the synovial sac, already mentioned asprotruding between the antero- and postero-lateral ligaments of that joint. We have already remarked that this is a point of interest to be rememberedin connection with the operation for quittor. Below and behind, theinternal face of the cartilage is united to the plantar cushion. 

[Illustration: FIG. 16. --EXTERNAL FACE OF THE OUTER LATERAL CARTILAGE. 1, External face of cartilage--(_a_) its upper border, (_b_) its posteriorborder, (_c_) its anterior border, (_d_) its inferior border; 2, the ospedis; 3, wing of os pedis. ]

The upper border, sometimes convex, sometimes straight, is thin andbevelled, and may easily be felt in the living animal. It is this borderthat the digital vessels cross to gain the foot, and the border is oftenbroken by a deep notch to accommodate them. The inferior border is attachedin front to the basilar and retrossal processes, behind which it blendswith the plantar cushion. The posterior border is oblique from before tobehind, and above to below, and joins the preceding two. The anteriorborder is oblique in the same direction, and is intimately attached to theantero-lateral ligament of the pedal articulation. The cartilages of thefore-feet are thicker and more extensive than those of the hind. 

2. THE PLANTAR CUSHION on FIBRO-FATTY FROG. --Composed of a fibrousmeshwork, in the interstices of which are lodged fine elastic andconnective fibres and fat cells, this wedge-shaped body occupies the spacebetween the two lateral cartilages, the extremity of the perforans tendon, and the horny frog. It offers for consideration an antero-superior and aninfero-posterior face, a base, an apex, and two borders. 

The antero-superior face is in contact with the terminal expansion of theperforans tendon. The infero-posterior face is covered by the keratogenousmembrane, and follows closely the shape of the horny frog, on whose innersurface it is moulded. It presents, therefore, at its centre a singleconical prolongation, the _Pyramidal Body_, which is continued behind, asis the horny frog, in the shape of two lateral ridges divided by a mediancleft. The _base_ of the cushion lies behind, and consists of two lateralmasses, _the Bulbs of the Plantar Cushion_. In front these are continuouswith the ridges of the pyramidal body, while behind they become confoundedwith the lateral cartilages and the coronary cushion. The _apex_ is fixedinto the plantar surface of the os pedis, in front of its semilunar ridge. The _borders_, right and left, are wider behind than before, and are inrelation with the inner faces of the lateral cartilages. 

H. THE KERATOGENOUS MEMBRANE. 

THE KERATOGENOUS, OR HORN-PRODUCING MEMBRANE, is in reality an extensionof the dermis of the digit. It covers the extremity of the digit as a sockcovers the foot, spreading over the insertion of the extensor pedis, thelower half of the external face of the lateral cartilages, the bulbs of theplantar cushion, the pyramidal body, the anterior portion of the plantarsurface of the os pedis, and over the anterior face of the same bone. Inturn, as the human foot with its sock is covered by the boot, this isencased by the hoof, the formation of which we shall study later. 

To expose the membrane for study the hoof must be removed. This may be donein two ways. By roasting in a fire, and afterwards dragging off the hornystructures with a pair of pincers, a knife having first been passed roundthe superior edge of the horny box. Or by maceration in water for severaldays, when the hoof will become loosened by the process of decomposition, and may be easily removed by the hands. The latter method is less likelyto injure the sensitive structures, and will expose them with a freshappearance for observation. 

For purposes of description the keratogenous membrane is divided into threeregions:

 1. The Coronary Cushion. 2. The Velvety Tissue. 3. The Podophyllous Tissue, or the Sensitive laminæ. 

1. THE CORONARY CUSHION. In the foot stripped of the hoof the coronarycushion is seen as a rounded structure overhanging the sensitive laminæafter the manner of a cornice. It extends from the inner to the outer bulbsof the plantar cushion, and is bounded above by the perioplic ring, andbelow by the laminæ. 

When _in situ_ it is accommodated by the _Cutigeral Groove_, a cavityproduced by the bevelling out of the superior portion of the inner face ofthe wall of the hoof. Its superior surface is covered by numerous elongatedpapillæ, set so closely as to give the appearance of the 'pile' of velvet. This is observed to the best advantage with the foot immersed in water. 

_The Superior Border_ of the cushion is bounded by the _Perioplic Ring_, the cells of which have as their function the secreting of the _Periople_, a layer of thin horn to be noted afterwards as covering the external faceof the wall. From the perioplic ring the cushion is separated by a narrowand shallow, though well-marked, groove. 

The inferior border is bounded by the sensitive laminæ. 

[Illustration: FIG. 17. --THE KERATOGENOUS MEMBRANE (VIEWED FROM THE SIDE). (THE HOOF REMOVED BY MACERATION. ) 1. The sensitive laminæ, or podophylloustissue; 2, the coronary cushion; 3, the perioplic ring; 4, portion ofplantar cushion; 5, groove separating perioplic ring from coronary cushion;6. The sensitive sole. ]

The upper portions of the laminæ, those in contact with the cushion, arepale in contrast with the portions immediately below, and thus there isgiven the appearance of a white zone adjoining the inferior border of thecushion. 

Widest at its centre, the cushion narrows towards its extremities, which, arriving at the bulbs of the plantar cushion, bend downwards into thelateral lacunæ of the pyramidal body, where they merge into the velvetytissue of the sole and frog. 

The papillæ of the coronary cushion secrete the horn tubules forming thewall, and the papillæ of the perioplic ring secrete the varnish-like veneerof thin horn covering the outside surface of the hoof. 

[Illustration: FIG. 18. --THE KERATOGENOUS MEMBRANE (VIEWED FROM BELOW). (THE HOOF REMOVED BY MACERATION. ) 1, The sensitive sole; 2, the sensitivefrog[A]--(a) its median lacuna, (6) its lateral lacuna; 3. V-shapeddepression accommodating the toe-stay; 4, the sensitive laminæ whichinterleave with the horny laminæ of the bar. ]

[Footnote A: The sensitive frog thinly invests the plantar cushion orfibre-fatty frog, the outline of which is here indicated. ]

2. THE VELVETY TISSUE. --This is the portion of the keratogenous membranecovering the plantar surface of the os pedis and the plantar cushion. Tothe irregularities of the latter body--its bulbs, pyramidal body, and itslacunæ--it is closely adapted. Its surface may, therefore, be divided into_(a) The Sensitive Frog_, and _(b) The Sensitive Sole_. 

_(a) The Sensitive Frog_ is that part of the velvety tissue moulded on thelower surface of the plantar cushion. The shape of the plantar cushion hasalready been described as identical with that of the horny frog. It onlyremains to state that, like the coronary cushion, the surface of thesensitive frog is closely studded with papillæ. The cells clothing thepapillæ are instrumental in forming the horny frog. 

_(b) The Sensitive Sole_. --As its name indicates, this is the portion ofthe keratogenous membrane that covers the plantar surface of the os pedis. It also is clothed with papillæ, which again give rise to the formation ofthat part of the horny box to which they are adapted--namely, the sole. 

3. THE PODOPHYLLOUS TISSUE, OR SENSITIVE LAMINÆ. --This portion of thekeratogenous membrane is spread over the anterior face and sides of the ospedis, limited above by the coronary cushion, and below by the inferioredge of the bone. It presents the appearance of fine longitudinal streaks, which, when closely examined with a needle, are found to consist ofnumerous fine leaves. These extend downwards from the lower border of thecoronary cushion to the inferior margin of the os pedis. At this point eachterminates in several large villous prolongations, which extend into thehorny tubes at the circumference of the sole. At the point of the toe thismembrane sometimes shows a V-shaped depression, into which fits a invertedV-shaped prominence on the inner surface of the wall at this point. 

The sensitive laminæ increase in width from above to below. Their freemargin is finely denticulated, while their sides are traversed from top tobottom by several folds (about sixty), which, examined microscopically, areseen to consist of secondary leaves, or _laminellæ_. 

Examined on the foot, deprived of its horny covering, the sensitive laminæare, the majority of them, in close contact with each other. In the normalstate this is not so. The interstices between the leaves are then occupiedby the horny leaves, to be afterwards described as existing on the innersurface of the wall. 

Reaching and rounding the heels, the sensitive laminæ extend forward for ashort distance, where they interleave with the horny laminæ of the bars. 

Much discussion has centred round the point as to whether or no the cellsof the sensitive laminæ take any share in the formation of the horn of thewall. This will be alluded to in a future chapter. 

I. THE HOOF. 

Removed from the foot by maceration a well-shaped hoof is cylindro-conicalin form, and appears to the ordinary observer to consist of a box or casecast in one single piece of horn. Prolonged maceration, however, will showthat the apparently single piece is divisible into three. These are knownas (1) THE WALL, (2) THE SOLE, and (3) THE FROG. In addition to these, wehave also an appendage or circular continuation of the frog named (4) THEPERIOPLE, or CORONARY FROG BAND. These various divisions we will studyseparately. 

1. THE WALL is that portion of the hoof seen in front and laterally whenthe horse's foot is on the ground. Posteriorly, instead of being continuedround the heels to complete the circle, its extremities become suddenlyinflected downwards, forwards, and inwards. These inflections can only beseen with the foot lifted from the floor, and form the so-called _Bars_. Itwill be noticed, too, with the foot lifted, that the wall projects beyondthe level of the other structures of the plantar surface, taking uponitself the bearing of the greatest part of the animal's weight. 

The horn of the wall, viewed immediately from the front, is known as the_Toe_, which again is distinguished as _Outside Toe_ or _Inside Toe_, according as the horn to its inner or outer aspect is indicated. Theremainder of the external face of the wall, that running back to the heels, is designated the _Quarters_. 

In the middle region of the toe, the wall following the angle of the bonesis greatly oblique. This obliquity decreases as the quarters are reached, until on reaching the heels the wall is nearly upright. 

[Illustration: FIG. 19. --THE WALL OF THE HOOF. 1, The toe; 2, inner toe; 3, outside toe; 4, the quarter; 5, entigeral groove; 6, horny laminæ. ]

For observation the wall offers two faces, two borders, and twoextremities. 

_The External Face_ is convex from side to side, but straight from theupper to the lower border. Examined closely, it is seen to be made up ofclosely-arranged parallel fibres running in a straight line from the upperto the lower border, and giving the surface of the foot a finely striatedappearance. In addition to these lines, which are really the horn tubules, the external face is marked by a series of rings which run horizontallyfrom heel to heel. These are due to varying influences of food, climate, and slight or severe disease. This will be noted again in a later page. Ina young and healthy horse the whole of the external face of the wallis smooth and shining. This appearance is due to a thin layer of horn, secreted independently of the wall proper, termed the periople. 

[Illustration: FIG. 20. --INTERNAL FEATURES OF THE WALL, FROG, AND SOLE(MESIAN SECTION OF HOOF). 1, Horny laminæ covering internal face of wall;2, superior border of wall; 3, junction of wall with horny sole; 4, thecutigeral groove; 5, the horny sole; 6, the horny frog (that portion ofit known as the 'frog-stay'); 7, inverted V-shaped ridge on wall and sole(known as the 'toe-stay'); 8, anterior face of wall; 9, inferior border ofwall. ]

_The Internal Face_ of the wall, that adapted to the sensitive laminæ, is closely covered over its entire surface with white parallel leaves_(Keraphyllæ_, or horn leaves, to distinguish them from the _Podophyllæ_, or sensitive leaves). These keraphyllæ dovetail intimately with thesensitive laminæ, covering the os pedis. Running along the superior portionof the inner face is the _Cutigeral Groove_. This cavity has been mentionedbefore as accommodating the coronary cushion, whose shape and generalcontour it closely follows, being widest and deepest in front, andgradually decreasing as it proceeds backwards. It is hollowed out at theexpense of the wall, and shows on its surface numberless minute openingswhich receive the papillæ of the coronary cushion. 

At the bottom of the internal face, at the point where the toe joins thesole, will be noted the before-mentioned inverted V-shaped prominence. Its position will be clearly understood when we say that it gives theappearance of having been forced there by the pressure of the toe-clip ofthe shoe. This will be noted again when dealing with the sole. 

_The Inferior Border_ of the wall offers little to note. It is that portionin contact with the ground, and subject to wear. A point of interest is itsunion with the sole. This will be noticed in a foot which has just beenpared as a narrow white or faint yellow line on the inner or concave faceof the wall at its lower portion. It marks the point where the horny leavesof the wall terminate and become locked with corresponding leaves of thecircumference of the sole. 

_The Superior Border_ follows closely the line marked by the perioplic ringand the groove separating the latter from the coronary cushion. 

_The Extremities_ of the wall are formed by the abruptly reflected portionsof the wall at the heels. Termed by some the 'Inflexural Nodes, ' they arebetter known to us as the '_Points of the Heels_. '

2. THE SOLE. --The sole is a thick plate of horn which, in conjunctionwith the bars and the frog, forms the floor of the foot. In shape it isirregularly crescentic, its posterior portion, that between the horns ofthe crescent, being deeply indented in a V-shaped manner to receive thefrog. Its upper surface is convex, its lower concave. It may be recognisedas possessing two faces and two borders. 

_The Superior or Internal Face_ is adapted to the sole of the os pedis. Itshighest point, therefore, is at the point of its V-shaped indentation. Fromthis point it slopes in every direction downwards and outwards until nearthe circumference. Here it curves up to form a kind of a groove in whichis lodged the inferior edge of the os pedis. In the centre of its anteriorportion--that is to say, at the toe--will be seen a small inverted V-shapedridge, which is a direct continuation of the same shaped prominence beforementioned on the internal face of the wall. This Fleming has termed thetoe-stay, from a notion that it serves to maintain the position of the ospedis. The whole of the superior face of the sole is covered with numerousfine punctures which receive the papillæ of the sensitive sole. 

_The Inferior Face_ is more or less concave according to circumstances, itsdeepest part being at the point of the frog. Sloping from this point to itscircumference, it becomes suddenly flat just before joining the wall. Itshorn in appearance is flaky. 

[Illustration: FIG. 21. --INFERIOR ASPECT OF HOOF. _a_ The inferior face ofhorny sole; _b_, inferior border of the wall; _c_, body or cushion of thefrog; _d_, median lacuna of the frog; _e_, lateral lacuna of the frog; _f_, the bar; _g_, the quarter; _h_, the point of the frog; _i_ the heel. ]

_The External Border_ or Circumference is intimately dovetailed with thehorny laminæ of the wall. At its circumference the sole, if unpared, isordinarily as thick as the wall. This thickness is maintained for a shortdistance towards its centre, after which it becomes gradually more thin. 

_The Internal Border_ has the shape of an elongated V with the apexpointing forwards. It is much thinner than the external border, and, like it, is dovetailed into the horny laminæ of the inflections of thewall--namely, the bars. In front of the termination of the bars it isdovetailed into the sides and point of the frog. Where unworn by contactwith the ground, the horn of the sole is shed by a process of exfoliation. 

3. THE FROG. --Triangular or pyramidal in shape, the frog bears a closeresemblance to the form of the plantar cushion, upon the lower surface ofwhich body it is moulded. It offers for consideration two faces, two sides, a base, and a point or summit. 

[Illustration: FIG. 22. --HOOF WITH THE SENSITIVE STRUCTURES REMOVED. 1, Superior face of horny frog; 2, the frog-stay; 3, the lateral ridges ofthe frog's superior surface; 4, the horny laminæ at the inflections of thewall. ]

_The Superior Face_ is an exact cast of the lower surface of the plantarcushion. It shows in the centre, therefore, a triangular depression, withthe base of the triangle directed backwards. Posteriorly, the depressionis continued as two lateral channels divided by a median ridge. The medianridge widens out as it passes backwards, forming the larger part of theposterior portion of the frog. This median ridge fits into the cleft of theplantar cushion. It serves to prevent displacement of the sensitive fromthe horny frog, and has been rather aptly termed the '_Frog-stay_. '

_The Inferior Surface_ is an exact reverse of the superior. The triangulardepression of the superior surface is represented in the inferior surfaceby a triangular projection, and the ridge-like frog-stay of the uppersurface is represented below by a median cleft, the _Median Lacuna_ of thefrog. The triangular projection in front of the median lacuna is thebody or cushion of the frog. It is continued backwards as two ridge-likebranches, which, at the points of the heels, form acute angles with thebars. On the outer side of each lateral ridge is a fissure. These are knownas the Lateral Lacunæ. 

_The Sides_ of the frog are flat and slightly oblique. They are closelyunited to the bars and to the triangular indentation in the posteriorborder of the sole. 

_The Base_ of the frog is formed by the extremities of its branches, which, becoming wider and more convex as they pass backwards, form two rounded, flexible, and elastic masses separated from each other by the medianlacuna. These constitute the 'glomes' of the frog. They are continuous withthe periople. 

_The Point of the Frog_ is situated, wedge-like, within the triangularnotch in the posterior border of the sole. 

4. THE PERIOPLE, OR CORONARY FROG BAND. --This is a continuation of thesubstance of the frog around the extreme upper surface of the hoof. It iswidest at the heels over the bulbs or glomes of the frog, and graduallynarrows as it reaches the front of the hoof. It is, in reality, a thinpellicle of semi-transparent horn secreted by the cells of the perioplicring. When left untouched by the farrier's rasp it serves the purpose, byacting as a natural varnish, of protecting the horn of the wall from theeffects of undue heat or moisture. 

CHAPTER III

GENERAL PHYSIOLOGICAL AND ANATOMICAL OBSERVATIONS

The matter embraced by the heading of this chapter will offer fordiscussion many subjects of great interest to the veterinary surgeon. Around some of them debate has for many years waxed more than keen. Of thepoints in dispute, some of them may be regarded as satisfactorily settled, while others offer still further room for investigation. 

In this volume we can only hope to deal with them in brief, and must selectsuch as appear to have the greatest bearing on the veterinarian's everydaypractice. 

Always prolific of heated discussion has been one question: 'Are the hornylaminæ secreted by the sensitive?' To answer this satisfactorily, it willbe best to give a short account of the mode of production of the hoof ingeneral. 

A. DEVELOPMENT OF THE HOOF. 

Starting with the statement that it is epidermal in origin, we willfirst consider the structure of the skin, and follow that with a briefdescription of the structure and mode of growth of the human nail, a shortstudy of which will greatly assist us when we come to investigate themanner of growth of the horse's hoof. 

THE SKIN is composed of two portions, the EPIDERMIS and the CORIUM. 

THE EPIDERMIS is a stratified epithelium. The superficial layers of thecells composing it are hard and horny, while the deeper layers are soft andprotoplasmic. These latter form the so-called _Retae Mucosum_ of Malpighi. 

[Illustration: FIG. 23. --VERTICAL SECTION OF EPIDERMIS (HUMAN). (AFTERRANVIER) _A_, The horny layer of the epidermis; _B_, the rete mucosum;_a_, the columnar pigment-containing cells of the rete; _b_, the polyhedralcells; _c_, the stratum granulosum; _d_, the stratum lucidum; _e_, swollenhorny cells; _f_ the stratum squamosum. ]

Commencing from below and proceeding upwards, we find that the lowermostcells of the rete mucosum, those that are set immediately on the corium, are columnar in shape. In animals that have a coloured skin these cellscontain pigment granules. Directly superposed to these we find cells whichin shape are polyhedral. Above them, and forming the most superficial layerof the rete mucosum, is a series of flattened, granular-looking cells knownas the _stratum granulosum_. 

Immediately above the stratum granulosum the horny portion of the epidermiscommences. In the human skin this is formed of three distinct layers. Undermost a layer of clear compressed cells, the _stratum lucidum_. Next above it a layer of swollen cells, the nuclei of which areindistinguishable. Finally, a surface layer of thin, horny scales, the_stratum squamosum_, which become detached and thrown off in the form ofscurf or dandruff. In the skin of the horse, except where it is thickest, these layers are not clearly defined. 

It is the Malpighian layer of the epidermis that is most active in celldivision. As they are formed the new cells push upwards those alreadythere, and the latter in their progress to the surface undergo a chemicalchange in which their protoplasm is converted into horny material. Thischange, as we have already indicated, takes place above the stratumgranulosum. 

In addition to its constant formation of cells to replace those castoff from the surface, the active proliferation of the elements of theMalpighian layer is responsible for the development of the variousappendages of the skin, the hairs with their sebaceous glands, the sweatglands, horny growths and the hoof, and, in the human subject, the nail. These occur as thickenings and down-growths of the epithelium into thecorium. 

The epidermis is devoid of bloodvessels, but is provided with fine nervefibrils which ramify between the cells of the rete mucosum. 

THE CORIUM is composed of dense connective tissue, the superficial layerof which bears minute papillæ. These project into the epidermis, which ismoulded on them. For the most part the papillæ contain looped capillaryvessels, rendering the superficial layer of the corium extremely vascular. Why this must be a moment's reflection will show. The epidermis, as we havealready said, is devoid of bloodvessels. It therefore depends entirely forits nourishment upon the indirect supply it receives from the vessels ofthe corium. The need for extreme vascularity of the corium is furtherexplained when we call to mind the constant proliferation and casting offof the cells of the epidermis, the growth of the hairs, the production ofthe horn of the hoof, and the work performed by the numerous sweat andother glands. 

Others of the papillæ contain nerves, ending here in tactile corpuscles, orcontinuing, as we have mentioned before, to ramify as fine fibrils in therete mucosum of the epidermis. 

THE HAIRS are growths of the epidermis extending downwards into the deeperpart of the corium. Each is developed in a small pit, the _Hair Follicle_, from the bottom of which it grows, the part lying within the follicle beingknown as the _Root_. It is important to note their structure, as it will beseen later that they bear an extremely close relation to the horn of thehoof. 

Under a high power of the microscope, and in optical section, the centralportion of a hair is tube-like. In some cases the cavity of the tube isoccupied by a dark looking substance formed of angular cells, and known asthe _Medulla_. The walls of the tube, or the main substance of the hair, ismade up of a pigmented, _horny, fibrous material_. This fibrous structureis covered by a delicate layer of finely imbricated scales, and is termedthe _Hair Cuticle_. 

The root of the hair, that portion within the follicle, has exactly thesame formation save at its extreme end. Here it becomes enlarged intoa knob-like formation composed of soft, growing cells, which knob-likeformation fits over a vascular papilla projecting up in the bottom of thefollicle. 

We have already stated that the hairs are down-growths of the epidermis. It follows, therefore, that the hair follicles, really depressionsor cul-de-sacs of the skin itself, are lined by epithelial cells andconnective tissue. So closely does the epidermal portion of the follicleinvest the hair root that it is often dragged out with it, and is knownas the _Root Sheath_. This is made up of an outer layer of columnar cells(_the outer root sheath_) corresponding to the Malpighian layer of theepidermis, and of an inner horny layer, next to the hair, corresponding tothe more superficial layer of the epidermis, and known as the _inner rootsheath_. 

The hair grows from the bottom of the follicle by a multiplication of thecells covering the papilla upon which its root is moulded. When a hair iscast off a new one is produced from the cells covering the papilla, or, incase of the death or degeneration of the original papilla, the new hair isproduced from a second papilla formed in place of the first at the bottomof the follicle. 

[Illustration: FIG. 24. --SECTION OF SKIN WITH HAIR FOLLICLE AND HAIR. _a_, The hair follicle; _b_, the hair root; _c_, the medulla; _d_, the haircuticle; _e_, the outer root sheath; _f_, the inner root sheath; _g_, thepapilla from which the hair is growing; _h_, a sebaceous gland; _i_, asudoriferous gland. ]

THE SEBACEOUS GLANDS are small saccular glands with their ducts openinginto the mouths of the hair follicles. They furnish a natural lubricant tothe hairs and the skin. 

THE SUDORIFEROUS OR SWEAT GLANDS are composed of coiled tubes which lie inthe deeper portion of the skin, and send up a corkscrew-like duct to openon the surface of the epidermis. They are numerous over the whole of thebody. 

[Illustration: FIG. 25. --LONGITUDINAL SECTION THROUGH NAIL AND NAIL-BED OFA HUMAN FOETAL FINGER. [A] _a_, The nail; _b_, the rete mucosum; _c_, thelongitudinal ridges of the corium. ]

[Footnote A: Seeing that the section is a longitudinal one, it would appearfrom the way the ridges cut that they are running transversely beneath thenail. Their extreme delicacy, however, prevents a single one showing itselfalong the length of the section, and their constant accidental cuttingmakes them _appear_ to run transversely (H. C. R. ). ]

THE HUMAN NAILS are thickenings of the lowermost layer of the horny portionof the epidermis, the stratum lucidum. They are developed over a modifiedportion of the corium known as the nail-bed. The horny substance of thenail is composed of clear horny cells, and rests immediately upon aMalpighian layer similar to that found in the epidermis generally. Insteadof the papillæ present elsewhere in the skin, the corium of the nail-bed ismarked by longitudinal ridges, a similar, though less distinct, arrangementto that found in the laminæ of the horse's foot. 

Having thus paved the way, we are now in a better position to discuss ouroriginal question (Are the horny laminæ secreted by the sensitive?), and better able to appreciate the work that has been done towards theelucidation of the problem. 

A most valuable contribution to this study is an article published in 1896by Professor Mettam. [A] Here the question is dealt with in a manner thatmust effectually silence all other views save such as are based uponsimilar methods of investigation--namely, histological examination ofsections of equine hoofs in various stages of foetal development. 

[Footnote A: The _Veterinarian_, vol. Lxix. , p. 1. ]

Professor Mettam commences by drawing attention to the error that hasbeen made in this connection by studying the soft structures of the footseparated by ordinary putrefactive changes from the horny covering. "Inthis way, " the writer points out, "a wholly erroneous idea has crept inas to the relation of the one to the other, and the two parts have beentreated as two anatomical items, when, indeed, they are portions of oneand the same thing. As an illustration, and one very much to the point atissue, the soft structures of the foot are to the horny covering what thecorium of the skin and the rete Malpighii are to the superficial portionsof the epidermis. Indeed, the point where solution of continuity occurs inmacerating is along the line of the soft protoplasmic cells of the rete. "

In the foregoing description of the skin we have seen that the coriumis not a _plane_ surface, but that it is studded by numerous papillaryprojections, and that these projections, with the depressions between them, are covered by the cells of the epidermis. 

The corium of the horse's foot, however, although possessed of papillæ incertain positions (as, for example, the papillæ of the coronary cushion, and those of the sensitive frog and sole), has also most pronounced ridges(laminæ) which run down the whole depth of the os pedis. Each lamina againcarries ridges (laminellæ) on its lateral aspects, giving a section ofa lamina the appearance of being studded with papillæ. We have alreadypointed out the ridge-like formation of the human nail-bed, and noted that, with the exception that the secondary ridges are not so pronounced, it isan exact prototype of the laminal formation of the corium of the horse'sfoot. 

The distribution of the laminæ over the foot we have discussed in thechapter devoted to the grosser anatomy. In a macerated foot the sensitivelaminæ of the corium interdigitate with the horny laminæ of the hoof; thatis to say, there is no union between the two, for the simple reason that ithas been destroyed; they simply interlock like the _unglued_ junction ofa finely dovetailed piece of joinery. But no further, however, than theirregularities of the underneath surface of the epidermis of the skin canbe said to interlock with the papillæ of the corium does interlocking ofthe horny and sensitive laminæ occur. It is only apparent. The horny laminæare simply beautifully regular epidermal ingrowths cutting up the coriuminto minute leaf-like projections. 

In a macerated specimen, then, the exposed sensitive structures of thefoot exhibit the corium as (1) the _Coronary Cushion_, fitting into thecutigeral groove; (2) the _Sensitive Laminæ_, clothing the outer surface ofthe terminal phalanx, and extending to the bars; (3) the _Plantar Cushion_, or sensitive frog; and (4) the _Sensitive Sole_. 

The main portion of the wall is developed from the numerous papillæcovering the corium of the coronary cushion. We have in this way numberlessdown-growing tubes of horn. Professor Mettam describes their formation ina singularly happy fashion: "Let the human fingers represent the coronarypapillæ, the tips of the fingers the summits of the papillæ, and the foldsof skin passing from finger to finger in the metacarpo-phalangeal regionthe depressions between the papillæ. Imagine that all have a continuouscovering of a proliferating epithelium. Then we shall have a more or lesscontinuous column of cells growing from the tip of the finger or papilla (ahollow tube of cells gradually moving from off the surface of the fingeror papilla like a cast), and similar casts are passing from off all thefingers or papillæ. "

From this description it will be noticed that each down-growing tube ofhorn bears a striking resemblance to the growth of a hair, described on p. 47. In fact, the horn tube may be regarded as what it really is, a modifiedhair. 

We next continue Professor Mettam's illustration, and note how the modifiedhairs or horn tubes become as it were matted together to form the hoofwall. The cells lining the depressions are also proliferating, and theirprogeny serve to cement together the hollow casts of the papillæ, thusgiving the _inter_-tubular substance. We have thus produced hollow tubes, united together by cells, all arising from the rete Malpighii of thecoronary corium. Section of the lower part of the horn tubes shows them tocontain a cellular debris. 

Thus, in all, in the horn of the wall we find a tubular, an intertubular, and intratubular substance. In fact, hairs matted together by intertubularmaterial, and only differing from ordinary hairs in their development inthat they arise, not from papillæ sunk in the corium, but from papillæprojecting from its surface. 

Although this disposes of the wall proper, there still confronts us thequestion of the development of the horny laminæ. To accurately determinethis point it is absolutely essential to examine, histologically, the feetfrom embryos. 

In the foot of any young ungulate in the early stages of intra-uterinelife horizontal sections will show a covering of epidermis of varyingthickness. [A] This may be only two or three cells thick, or may consist ofseveral layers. Lowermost we find the cells of the rete Malpighii. As somecriterion of the activity with which these are acting, it may be noted thatwith the ordinary stains their nuclei take the dye intensely. The cells ofthis layer rest upon a basement membrane separating the epidermis from thecorium. At this stage _the corium has a perfectly plane surface_. 

[Footnote A: Equine foetus, seventy-seven days old. ]

[Illustration: FIG. 26. --SECTION OF FOOT OF EQUINE FOETUS, SEVENTY-SEVENDAYS OLD. The rete Malpighii rests on a plane corium; the rent in thesection is along the line of the cells of the rete (Mettam). ]

[Illustration: FIG. 27. --SECTION FROM FOOT OF SHEEP EMBRYO. It shows apronounced epithelial ingrowth into the corium (Mettam). ]

The next stage will demonstrate the first step in the formation of thesensitive laminæ. [A] The plain surface of the corium has now become brokenup, and what is noticed is that the broken-up appearance is due to theepithelial cells irrupting and advancing _en échelon_ into its connectivetissue. Each point of the ingrowing lines of the _échelon_ has usuallyone cell further advanced into the corium than its neighbours, and may betermed the _apical cell_. The fine basement membrane separating epitheliumfrom corium is still clearly evident. This epidermal irruption of thecorium takes place at definite points right round the foot. It is extremelyprobable, however, that it commences first at the toe and spreadslaterally. 

[Footnote A: Sheep embryo, exact age unknown. ]

As yet, these cellular ingrowths (which are destined to be the _horny_laminæ, and cut up the corium into _sensitive_ laminæ) are free fromirregularities or secondary laminæ. Before these are to be observed otherchanges in connection with the ingrowths are to be noticed. 

[Illustration: FIG. 28. --SECTION FROM CALF EMBRYO. The epithelial ingrowthshang down from the epidermis into the corium like the teeth of a comb(Mettam). ]

The first is merely that of elongation of the epithelial processes into theconnective tissue, until the rete Malpighii gives one the impression thatit has hanging to its underneath surface and into the corium a number ofthorn-like processes. These extend all round the front of the foot, andeven in great part behind. Accompanying this elongation of the processesis a condensation of the epithelial cells immediately above the reteMalpighii, with a partial or total loss of their nuclei. This is the firstappearance of true horn, and its commencement is almost coincident with thefirst stages of ossification of the os pedis. 

[Illustration: FIG. 29. --SECTION OF AN EPITHELIAL INGROWTH FROM AN EQUINEFOETUS. It shows commencing secondary laminar ridges. In the centre areepithelial cells which are undergoing change into horny elements to formthe horn core, or 'horny laminæ' (Mettam). ]

With the appearance of horn comes difficulty of sectioning. The lastspecimen that Professor Mettam was able to satisfactorily cut upon themicrotome was from a foetus between three and four months old. In this thesecondary laminar ridges were clearly indicated, and the active layer ofthe rete Malpighii could be traced without a break from one ingrowingepithelial process to the next, and around this, following all theirregularities of its outline, and covering the branches of the nascentlaminæ. The laminæ mostly show this branching as if a number of differentgrowing points had arisen, each to take on a function similar to theepithelial process as it at first appeared. 

In the centre of the processes a few nuclei may be observed, but they arescarce, and stain only faintly; they have arisen from the cells of the reteMalpighii which have grown into the corium. In fact, the active cells arepassing their daughters into the middle of the process, and these passthrough similar stages as those derived from the ensheathing epidermis. Inother words, the daughter cells of the constituents of the rete Malpighiiwhich have grown into the corium pass through a degeneration preciselysimilar to that undergone by cells shed at desquamation, or those whicheventually give rise by their agglutination to a hair. 

This is the real origin of the horny laminæ, and the thickness of these isincreased merely by an increase in the area covered by the cells of therete Malpighii--i. E. , by the development of secondary laminar ridges. Ifa section from a foal at term be examined, the processes will be found faradvanced into the corium, and, occupying the axis of each process, willbe seen a horny plate, continuous with the horn of the wall. No line ofdemarcation can be observed between the horn so formed and the intertubularmaterial of the wall. They merge into and blend with each other, with noindication of their different origins. The cells that have invaded thecorium have thus _not lost their horn-forming function_. There has merelybeen an increase in the area for horn-producing cells. The horny processesare continuous with the hoof proper at the point where the epithelialingrowth first commenced to invade the corium, and fuses here with thehorn derived from the cells of the rete Malpighii which have _not_ growninwards, and which are found between the processes in the intact foot. Fromthis it is clear that some considerable portion of the horn of the wall isderived from the cells of the rete Malpighii covering the corium of thefoot. It becomes even more clear when we remember the prompt appearance ofhorn in cases where a portion, or the whole, of the wall has been removedby operation or by accident (see reported cases in Chapter VII. ). 

The activity of the cells of the rete Malpighii of the corium covering theremainder of the foot will be quite as necessary as the activity of thecells of the coronary papillæ which form the horn tubes themselves. 'For, 'in Professor Mettam's own words, 'I am inclined to believe that much of the"white line" which is found uniting the wall of the hoof to the sole hasbeen derived from the horn formed from the rete of the foot corium. Thisorigin will explain the absence of pigment from this thin uniting "line, "as it does from the horn lining the interior of the wall. The cells of therete are free of colouring matter. '

[Illustration: FIG. 30. --SECTION THROUGH HOOF AND SOFT TISSUES OF A FOAL ATTERM. The horn of the wall is shown, and the horn-core ('horny laminæ') ofthe epithelial ingrowth. The latter has advanced far into the corium, andis now provided with abundant secondary laminar ridges (Mettam). ]

From the matter here given us it is easy to understand how, in a maceratedfoot, the appearance is given of interlocking of the sensitive and hornylaminæ. We see that the horny laminæ are ingrowths of the rete Malpighii, ploughing into and excavating the corium into the shape of leaves--thesensitive laminæ. Putrefactive changes simply break into two separateportions what originally was one whole, by destroying the cells along itsweakest part. This part is the line of soft protoplasmic cells of the reteMalpighii. Thus the more resistant parts (the horn on the one hand, and thecorium covering the foot on the other) are easily torn asunder. 

As a result of the evidence we have quoted, we are able to answer ouroriginal question in the affirmative. Seeing that the horny and thesensitive laminæ are both portions of the same thing--namely, a modifiedskin, in which the epidermis is represented by the horny laminæ, and thecorium by the sensitive--it is clear to see that the cells covering theinspreading horny laminæ are dependent for their growth and reproductionupon the cells with which they are in immediate contact--namely, thoseof the sensitive laminæ--and that therefore the sensitive laminæ areresponsible for the growth of the horny. 

B. CHEMICAL PROPERTIES AND HISTOLOGY OF HORN. 

Horn is a solid, tenacious, fibrous material, and its density in the hoofvaries in different situations. It is softened by alkalies, such as causticpotash or soda and ammonia, the parts first attacked being the commissures, then the frog, and afterwards the sole and wall. Strong acids, such assulphuric acid and nitric acid, also dissolve it. 

The chemical composition of the hoof shows it to be a modification ofalbumin, its analysis yielding water, a large percentage of animal matter, and materials soluble and insoluble in water. The proportions of these, asexisting in the various parts of the hoof, have been given by ProfessorClement as follows:

 Wall. Sole. Frog. Water 16. 12 36. 0 42. 0 Fatty matter 0. 95 0. 25 0. 50 Matters soluble in water 1. 04 1. 50 1. 50 Insoluble salts 0. 26 0. 25 0. 22 Animal matter 81. 63 62. 0 55. 78

Horn appears to be identical with epidermis, hair, wool, feathers, andwhalebone, in yielding 'keratin, ' a substance intermediate between albuminand gelatine, and containing from 60 to 80 per cent. Of sulphur. 

That horn is combustible everyone who has watched the fitting of a hot shoeknows. That it is a bad conductor of heat, the absence of bad after-effectson the foot testifies. 

[Illustration: FIG. 31. --PERPENDICULAR SECTION OF HORN OF WALL. ]

In a previous page we have described the manner of growth of the horntubules, and noted the direction they took in the wall; also, we havenoticed the existence between them of an intertubular horn or cement. 

Those who wish to give this subject further study will find an excellentseries of articles by Fleming in the _Veterinarian_ for 1871. Weshall content ourselves here with introducing one or two diagrams andphoto-micrographs, and dealing with the histology very briefly. 

Under the microscope the longitudinal striation of the wall is found to bedue to the direction taken by the horn tubules. 

Fig. 31 is a magnified perpendicular section of the wall. In it theparallel dark striæ are the horn tubules in longitudinal section. Thelighter striæ represent the intertubular material. 

Fig. 32 gives us the wall in horizontal section. To the left of thispicture we find the horn tubules cut across, and standing out as so manyconcentrically ringed circles. In the centre of the figure are seen thehorny laminæ, with their laminellæ, and the sensitive laminæ. The rightportion of the figure pictures the corium. 

[Illustration: FIG. 32. --HORIZONTAL SECTION OF HORN OF WALL. ]

Fig. 33 is, again, a horizontal section, cut this time at the junction ofthe wall with the sole. To the left are seen, again, the horn tubules ofthe wall, and to the centre the horny laminæ. In this position, however, the structures interdigitating with the horny laminæ are not sensitive, butare themselves horny. As the diagram shows, they contain regularly arrangedhorn tubules cut across obliquely. It is this horn which forms the 'whiteline. ' To the extreme right of the figure are seen the horn tubules of thesole. 

There remains now but to notice the arrangement of the horn tubules in thefrog. The peculiar, indiarubber-like toughness of this organ is well known. Histological examination gives a reason for this. 

[Illustration: FIG. 33. --HORIZONTAL SECTION OF HORN THROUGH THE JUNCTION OFTHE WALL WITH THE SOLE. _a_, Horn tubule of the wall; _b_, horn tubule ofthe sole; _c, d_, horny laminæ. ]

[Illustration: FIG. 34. --SECTION OF FROG THROUGH CORIUM AND HORN. The longfinger-like projections of corium into epidermis are sections of the longpapillæ from which the horn-tubes of the sole grow. In the stainableportion of the epidermis are to be clearly seen light and dark streakspointing out the alternate strata-like arrangement of cells mentioned inthe text (Mettam). ]

The horn tubules of the frog are sinuous in their course. This is accountedfor by the fact that in the horn of the frog there is a large amount ofintertubular material, this having the effect of frequently turning thehorn tubules from the straight. In addition to this, the intertubularmaterial has a peculiar arrangement of the cells composing it. Theseare laid down in alternating striæ (1) of cells with their long axeslongitudinal, and (2) of cells with their long axes horizontal. This isseen in Fig. 34, between the long papillæ of the corium, where the lines oflongitudinally arranged cells in horizontal section stand out darker thanthe adjoining strata in which their arrangement is horizontal. The tortuousdirection of the horn tubules, and the almost interlocking nature of thealternating strata of the intertubular material, together combine to givethe frog its characteristic toughness and resiliency. 

C. EXPANSION AND CONTRACTION OF THE HOOF. 

Among other questions productive of heated argument come those relating toexpansion of the horse's hoof. In the past many observers have strenuouslyinsisted on the fact that expansion and contraction regularly occur duringprogression. Opposed to them have been others equally firm in the beliefthat neither took place. Quite within recent times this question alsohas been settled once and for all by the experiments of A. Lungwitz, ofDresden. His conclusions were published in an article entitled 'Changes inForm of the Hoof under the Action of the Body-weight. '[A]

[Footnote A: _Journal of Comparative Pathology and Therapeutics_, vol. Iv. , p. 191. The whole of the matter in this article, from which we haveborrowed Figs. 35 and 36, is too long for reproduction here. It forms, however, most instructive reading, and its careful perusal will well repayeveryone interested in this most important question (H. C. R. ). ]

In connection with this it is interesting to note how, all unconsciously, two separate observers were simultaneously arriving by almost identicalmeans at an equally satisfactory answer to the question. Prior to thepublication of Lungwitz's article on the subject, Colonel F. Smith, A. V. D. , had arrived at similar conclusions by working on the same methods. 

[Illustration: Fig. 35. I. Electric Bell with Dry Element. A, Underpart, with box, for the dry element; 6, roller for winding up theconducting-wires; c, dry element, with screw-clamp for attachment of theconducting-wires; c', conducting-wire leading to the screw-clamp, withcontact-spring in c', Fig. 2, or to the wall in Fig. 3; d, upper part, withbell; d', conducting-wire to the shoe d' in Figs. 2 and 3; e, strap forslinging the apparatus around the body of the assistant or rider; f, connecting-wire between bell and dry element. ]

[Illustration: Fig. 35. II. Hoof Shod with Shoe provided with Toe-piece andCalkins; Wall of the Hoof covered with Tinfoil. A, Heel angle, with b, thecontact-screws; c, screw-clamp, with contact-spring (isolated fromthe shoe); c' conducting-wire from the same; d, screw-clamp, withconducting-wire (d') screwed into the edge of the shoe; e, nails isolatedby cutting a small window in the tinfoil. ]

[Illustration: Fig. 35. III. Hoof Shod with Plain Shoe; Horny Wall coveredwith Tinfoil. A, Toe and heel angle, with b, the contact-screws; c, conducting-wire passing from the tinfoil on the wall; d, conducting-wirepassing from the shoe; c', d', ends of the conducting-wires, which must beimagined connected with the ends c', d', passing from the apparatus. ]

It is unnecessary for our purpose here to minutely describe the exact_modus operandi_ of these two experimenters. Briefly, the method of inquiryadopted in each case was the 'push and contact principle' of the ordinaryelectric bell, and the close attention which was paid to detail will besufficiently gathered from Figs. 35 and 36. 

[Illustration: Fig. 36. I. LEFT FORE-FOOT SHOD AND MOUNTED TO RECOGNISE THESINKING OF THE SOLE. _a_, Iron plate covering the inner half of the hornysole; _b_, openings in the same, with screw-holes for the reception of thecontact-screw _c_ (the part of the sole under the plate is covered withtinfoil, which at _d_ passes out under the outer branch of the shoe, andbecomes connected with the tinfoil of the wall; in order to give thefreshly applied tinfoil a better hold, copying-tacks are at _e_ passedthrough it into the horn, and one is similarly used to protect the tinfoilat the place where the contact-screw touches the latter); _f_, holeswith screw thread for the fastening of the angle required to measure themovement of the wall, and also for the fastening of the conducting-wire, _g; h_, conducting-wire passing from the tinfoil; _i_, isolated nails. ]

[Illustration: Fig. 36. II. BAR-SHOE WITH OPENINGS. _a_, Near the innermargin and in the longitudinal bar; _b_, for the reception of thecontact-screw _c; d_, openings for fastening the angle and theconducting-wires. ]

After numerous experiments with the depicted contact-screws, moved to thevarious positions indicated in the drawings, the following conclusions werearrived at:

1. BEHAVIOUR OF THE CORONARY EDGE. --During uniform weighting of all fourhoofs the coronary edge shows a tendency to contraction in the anterior andlateral regions of the hoof, and a tendency to expansion posteriorly. Withheavy weighting of the hoof, which is shown by a backward inclination ofthe fetlock, contraction in the anterior and lateral regions is slight, butthe expansion behind, in the region of the heels, is distinct, commencinggradually in front, becoming stronger, and diminishing again posteriorly. The coronary edge of the heels becomes slightly bulged outwards. The bulbsof the heels swell up and incline a little backwards and downwards. 

When the fetlock is raised the expansion of the coronary edge of the heelsdisappears from behind forwards, passing forwards like a fluid wave. Inthe lateral and anterior regions of the coronary edge the contractiondisappears; and when the weight is thrown off the foot it passes into agentle expansion of the coronary edge of the toe. During the oppositemovement of the fetlock, that of sinking backwards, this change of form isexecuted in the converse manner. 

In short, the coronary edge resembles a closed elastic ring, which yieldsto pressure, even the most gentle, of the body-weight, in such a way that abulging out of any one part is manifested by an inward movement of anotherpart. 

In Fig. 37, _b_, the dotted line represents the changes of form incomparatively well-formed and sound hoofs at the moment of strongestover-extension[A] of the fetlock-joint. 

[Footnote A: The term 'over-extension, ' as employed by Lungwitz, isintended to indicate that position assumed by the fetlock-joint when theopposite foot is raised from the ground. ]

2. BEHAVIOUR OF THE SOLAR EDGE. --Under the action of the body-weight thisis somewhat different from that of the coronary edge. Anteriorly, and atthe sides, as far as the wall forms an acute angle with the ground, the tendency to expansion exists, but the change of form first becomesmeasurable in the region where the lateral cartilages begin. Quiteposteriorly the expansion again diminishes. 

Fig. 37, _a_, by the dotted line represents the expansion at the moment ofover-extension of the fetlock-joint. This expansion is itself rather lessthan at the coronary edge, and it shows itself distinctly _only when theweighted hoof is exposed to a counter-pressure on the sole and frog_, nomatter whether the counter-pressure is produced naturally or artificially. Thus anything tending to the removal of the pressure from below, such asa decayed condition of the frog or excessive paring in the forge, willdiminish the extent of expansion of the solar edge. 

Contraction of the solar edge of the heels occurs at the moment of greatestover-extension of the fetlock-joint--that is, in a foot with pressurefrom below absent. On the face of it, this appears impossible. Lungwitz, however, has perfectly demonstrated it; and, when dealing with thefunctions of the lateral cartilages in a later paragraph, we shall showreason for why it is but a simple and natural result of the foot dynamics. 

3. BEHAVIOUR OF THE SOLE. --The horny sole becomes flattened under theaction of the body-weight. This is most distinct at the solar branches, andgradually shades off anteriorly and towards the circumference. As might besupposed, width of hoof and thickness of the solar horn exert an influenceon the extent of this movement. The sinking of the horny sole is mostmarked in flat hoofs. 

D. THE FUNCTIONS OF THE LATERAL CARTILAGES. [A]

[Footnote A: Extracted from a paper by J. A. Gilruth, M. R. C. V. S. , in the_Veterinary Record_, vol. V. , p. 358. ]

We have just referred to contraction of the heels as taking the place of anormal expansion in those cases where ground frog-pressure was absent. Weshall readily understand this when we bear in mind the anatomy of theparts concerned, especially that of the plantar cushion. This wedge-shapedstructure we have already described as occupying the irregular spacebetween the two lateral cartilages, the extremity of the perforans tendon, and the horny frog. 

Now, when weight or pressure is exerted from above on to this organ, andthe _frog is in contact with the ground below_, it is clear from theposition the cushion occupies that, whatever change of form pressure fromabove will cause it to take, it must certainly be limited in variousdirections. 

[Illustration: FIG. 37. _a_, The dotted lines in this diagram represent theexpansion of the solar edge of the hoof at the moment of over-extension ofthe fetlock-joint; _b_, the dotted line represents the change in form ofthe coronary edge under similar circumstances. ]

Because of the shape of the cushion its change of form cannot be forwards(simultaneous pressure from above and below on to this wedge with its apexforwards must tend to give it a backward change of form). Because of thepastern being horizontal, and aiding in the downward pressure, itschange of form cannot be upwards. And because of the ground it cannot bedownwards. It follows, therefore, that the movement must be backwards andoutwards, being especially directed outwards because of its shape and themedian lacuna in its posterior half--this latter, the lacuna, accommodatingas it does the frog-stay, preventing the tendency to backward movementbecoming excessive, and directing the change of form to the sides. Wherethe greatest pressure is transmitted, then, is to the inner aspects of theflexible lateral cartilages. The coronary cushion being continuous with theplantar, the backward and outward movements of the latter will tend to pullupon and tighten the former, especially _in front_. This will account forthe contraction noted by Lungwitz in the _anterior half_ of the coronaryedge of the hoof. 

Remove the body-weight, and naturally the elastic nature of the lateralcartilages and the coronary and plantar cushions, with, in a less degree, that of the hoof, cause things to assume their normal position. 

Repeat the weighting of the hoof, in this second case _withoutfrog-pressure_, and we shall see at once that we have done away with one ofthe greatest factors in determining the outward and backward movements ofthe plantar cushion--namely, the pressure from below on its wedge-shapedmass. The movement of the plantar cushion will now be _downwards_ as wellas backwards; and, seeing that it is attached to the inner aspect of eachlateral cartilage, we shall expect these latter, by the downward movementof the plantar cushion, to be drawn _inwards_. This Lungwitz has shown tooccur. 

The chief function of the lateral cartilages, therefore, is to _receivethe concussion engendered by locomotion_, which concussion is directedbackwards and outwards by the pad-like plantar cushion. 

In addition to this, the lateral cartilages, together with the plantar andcoronary cushions, _play the part of a valve to the whole of the veins ofthe foot_. 

It is in this way: We have only to refer to the chapter on anatomy to seethat the whole of the foot is covered with a tissue of extreme vascularity. Thus we find papillæ--the over the coronary cushion; enlarged and modifiedpapillæ sensitive laminæ--covering the anterior face of the os pedis; andnumberless papillæ again covering the sole. There can be no doubt that thequantity of fluid brought by the bloodvessels of these papillæ to the footacts largely as a means of hydraulic protection to the soft structures. [A]In like manner as that delicate organ, the brain, is best protected bybeing floated upon the cerebro-spinal fluid and bloodvessels (which fluidstransmit waves of concussion or pressure _through_ the organ without injuryto the delicate cells forming it), so, in like manner, does the extremevascularity of the foot protect the cells of its softer structures from theeffects of pressure and concussion. 

[Footnote A: The _Veterinary Record_, vol. Iii. , p. 518. ]

That this law of hydraulics may operate in the horse's foot to the bestadvantage, the veins must be provided with valves, and valves of nomean strength. These we know to be absent. It is here that the lateralcartilages and the elastic substances of the coronary and plantar cushionsstep in to supply the deficiency. 

At the time when weight is placed upon the foot (with, of course, atendency to drive the blood upwards in the limb), and, therefore, the timewhen a valvular apparatus is needed to retain the fluid in the foot, wefind the wanting conditions supplied by the pressure outwards of theplantar cushion compressing the large plexuses of veins on each side of thelateral cartilages, to which plexuses, it will be remembered, the bulkof the venous blood from the foot was directed. A more perfect valvularapparatus, automatic and powerful, it would be difficult to imagine. 

E. GROWTH OF THE HOOF. 

We will conclude this chapter with a few brief remarks on the growth ofthe hoof. That the rate of growth is slow is a well-known fact to everyveterinarian, and it will serve for all practical purposes when we statethat, roughly, the growth of the wall is about 1/4 inch per month. Thisrate is regular all round the coronet, from which it follows that the timetaken for horn to grow from the coronary edge to the inferior marginwill vary according as the toe, the quarters, or the heels are underconsideration. 

As might naturally be expected, the rate of growth will depend on variousinfluences. Any stimulus to the secreting structures of the coronet, suchas a blister, the application of the hot iron, or any other irritant, results in an increased growth. Growth is favoured by moisture and bythe animal going unshod, as witness the effects of turning out to grass. Exercise, a state of good health, stimulating diets--in fact, anythingtending to an increased circulation of healthy blood--all lead to increasedproduction of horn. With the effects of bodily disease and of ill-formedlegs and feet on the wear of the hoof, and the growth of horn, we shall beconcerned in a future chapter. 

CHAPTER IV

METHOD OF EXAMINING THE FOOT

As a general rule, it may be taken that most diseases of the foot arecomparatively easy of diagnosis. When, however, the condition is one whichcommences simply with an initial lameness, the greatest care will have tobe exercised by the practitioner. 

What remarks follow here should rightly be confined to a treatise onlameness. This much, however, we may state: As compared with lamenessarising from abnormal conditions in other parts of the limb, that emanatingfrom abnormalities of the foot is easy of detection. With a case oflameness before him, concerning which he is in doubt, the practitionerremembers that a very large percentage may safely be referred to the foot, and, if wise, subjects the foot to a rigorous examination. 

Much may be gathered by first putting the animal through his paces. Whenat a trot, notice the peculiarity of the 'drop, ' whether any alteration ingoing on hard or soft ground, and watch for any special characteristic ingait. At the same time inquiry should be made as to the history of thecase; its duration; whether pain, as evidenced by lameness, is constant orperiodic; the effect of exercise on the lameness; and the length of timeelapsed since the last shoeing. 

This failing to reveal adequate cause for the lameness in any higher partof the limb, one is led, by a process of negative deduction, to suspectthe foot. If 'pointing' is a symptom, its manner is noticed. The foot iscompared with the other for any deviation from the normal. In some casesthe two fore or the two hind feet may differ in size. Though this may notnecessarily indicate disease, it may, nevertheless, be taken into accountif the lameness is not easily referable to any other member. Measurementwith calipers will then be of help, and a pronounced increase in size, especially if marked in one position only, given due consideration. Thehand is used upon each foot alternately to look for change of temperature, to detect the presence of growths small enough to escape the eye, and todiscover evidence of painful spots along the coronet. 

At this stage the method of percussion recommends itself, and in many casesno more useful diagnostic agent is to be found than the ordinary hammer. Asa preliminary, the foot of the sound limb should be always tapped first. This precaution will serve to bring to light what is frequently metwith--the aversion nervous animals sometimes exhibit to this manner ofmanipulation of the hoof. Unless this is done, the ordinary objection tointerference is apt to be read as evidence of pain. No aversion to themethod being shown, the suspected foot is gently tapped in various placesround the wall, a keen look-out being kept for any manifestation oftenderness. This may vary from a slight resentment to each tap, indicatedby a sudden lifting and setting down again of the foot, to a completeremoval of the foot from the ground, and a characteristic pawing of the airthat points out clearly enough the seat of pain. 

Evidence of pain once given, the tapping is persisted in until, in somecases, the exact position of the tender spot is definitely located. 

Failing evidence obtained from percussion, attention should next be givento the shoeing. We may add here that, even when difficulties have to beencountered in doing it, it is always a wise plan to have the shoe removed. 

The nails should be removed one by one, the course they have taken, theirpoint of emergence on the wall, and the condition of their broken ends allbeing carefully noted as they are withdrawn. 

The removed shoe should next be examined as to the coarseness or finenessof its punching and the 'pitch' of its nail-holes, and close attentiongiven to the shape of its bearing surface. 

From that we may pass to a consideration of the underneath surface ofthe foot. The drawing-knife should be run lightly over the whole of itssurface, the first thing to be noticed being the point of entrance of thenails as compared with the coarseness or fineness of the punching, and thestaining or otherwise of the horn immediately around. We may thus be guidedtowards mischief arising from tight nailing apart from actual prick of thefoot. 

This done, more than usual care should be taken in following up any othersmall prick or dark spot that may show itself upon the white surface of thecleaned sole. In any case, a suspicious-looking speck should be followed upwith the searcher until it is either cut out or is traced to the sensitivestructures. 

While this is done, we should also have noticed the condition of the hornat the seat of corn; should have noticed the shape of the heels, contractedor otherwise; and the appearance of the frog, clean or discharging. 

A point to be remembered in making this exploratory paring of the foot isthe peculiar consistency of the horn of the frog, and its tendency to hidethe existence of punctures. In like manner, as a pin pierces a piece ofindiarubber, and leaves no clearly visible trace of the hole it has made, so does a nail or other sharp object penetrate the frog, leaving but littleto show for the mischief that has been done. 

After all, even though we may have fully decided the foot is at fault, ourcase of lameness may remain obscure so far as a cause is concerned. Nothingremains, then, but to acknowledge the inability to discover it, to advocatepoulticing, or some other expectant palliative measure, and to bring thecase up for further examination at no distant date. Where, though wemay have suspected the foot, we have not been able to definitely assureourselves that there the mischief is to be found, a further method ofexamination presents itself--namely, subcutaneous injections of cocainealong the course of the plantar nerves. 

The salt of cocaine used is the hydrochlorate, 2-1/2 grains for a pony, 4 grains for a medium-sized animal, and 6 grains for a large horse. Asolution of this is made in boiled water (about 3 drams), and injected atthe seat of the lower operation of neurectomy. 

It is advisable to first render aseptic the seat of operation, and tosterilize both the needle and the syringe by boiling. A suitable point tochoose for the injection is exactly over the upper border of the lateralfaces of the two sesamoids, the needle being introduced behind the cordformed by the nerve and accompanying vessels, and parallel with it. 

It is possible that the vein or the artery may be wounded, but suchaccident is of little importance. All that is necessary in that case is topartly withdraw the needle and again insert it. It is advisable to use atwitch. 

When the needle is in position, the injection should be made slowly, andat the same time the point of the needle should be made to describe asemicircular sweep, so as to spread the solution over as wide an area as ispossible. 

Anæsthesia ensues in from six to twenty minutes, and if the cause of thelameness is below the point of injection the animal moves sound. 

Regarding this method of diagnosis, Professor Udriski of Bucharest, after aseries of trials, sums up as follows:

1. For the diagnosis of lameness cocaine injections are of veryconsiderable value. 

2. These injections should be made along the course of the nerves. 

3. Solutions heated to 40° or 50° C. Produced quicker, deeper, and longeranæsthesia than equally strong cold solutions. 

4. In the sale of horses cocaine injections conceal fraud. 

Cocaine being an irritant, it must be remembered that after the anæsthesiathe lameness is somewhat more marked than before. 

To the cocaine other practitioners add morphia in the followingproportions:

 Cocaine hydrochlorate 2-1/2 grains. Morphia 1-1/2 " Aqua destil 1-1/2 drams. 

As a diagnostic this mixture of the two is said to be far superior toeither cocaine or morphia alone. 

In connection with this subject, Professor Hobday has published, amongothers, the following cases illustrating the practical value of this methodof diagnosis:[A]

[Footnote A: The _Journal of Comparative Pathology and Therapeutics_ vol. Viii. , pp. 27, 43. ]

CASE I. --Cab gelding. Seat of lameness somewhat obscure; navicular diseasesuspected. Injected 2 grains of cocaine in aqueous solution on either sideof the limb, immediately over the metacarpal nerves. 

_Five Minutes_. --Lameness perceptibly diminished. 

_Ten Minutes_. --Lameness scarcely perceptible. 

CASE II. --Mare. Obscure lameness; foot suspected. Injected 30 minims of a 5per cent. Solution on either side of the leg just above the fetlock. 

_Ten Minutes_. --No lameness, thus proving that the seat of lameness wasbelow the point of injection. 

CASE III. --Cab gelding, aged, free clinique; Messrs. Elme's and Moffat'scase. Obscure lameness; foot suspected of navicular disease; very lame. Injected 30 minims of a 5 per cent. Solution of cocaine on either side ofthe leg over the metacarpal nerves. 

_Six Minutes_. --Lameness perceptibly less; there was no response whateveron the inside of the leg to the prick of a pin. On the outside, which hadnot been injected so thoroughly, there was sensation, although not so muchas in a healthy foot. 

_Ten Minutes_. --Lameness had almost disappeared; so much so, that theopinion as to navicular disease was confirmed, and neurectomy wasperformed. Immediately after this operation there was no lameness whatever. 

The same author also reports numerous cases among horses and cattle, dogsand cats, pointing out the toxic properties of the drug. The symptomsfollowing an overdose are interesting enough to relate here, and I selectthe following case of Professor Hobday's as being fairly typical:[A]

[Footnote A: _Loc. Cit_. ]

CASE IV. --Cart gelding. Free clinique; navicular disease. Injectedsubcutaneously over the metacarpal nerves on each side 6 grains of cocainein aqueous solution. During the operation the animal manifested no signsof pain whatever, not even when the nerve was cut. This animal receivedaltogether 12 grains of cocaine (3 grains were given on either side first, then fifteen minutes afterwards the same dose repeated). The effect wasmanifested on the system in ten minutes after the second injection byclonic spasms of the muscles of the limbs (the legs being involuntarilyjerked backwards and forwards at intervals of about twenty seconds), whichmaterially interfered with the performance of the operation. The animal wasalso continually moving the jaws, and was very sensitive to sounds, movingthe ears backwards and forwards. This hyperæsthesia, as evinced by themovement of the ears, lasted for some considerable time after the animalhad been allowed to get up. 

Cocaine hydrochlorate solutions, if intended to be kept for any length oftime, should have added to them when freshly made 1/200 part of boric acidin order to preserve them. Even then they are liable to spoil, and should, for subcutaneous injection, be made up just before needed for use. 

CHAPTER V

GENERAL REMARKS ON OPERATIONS ON THE FOOT

A. METHODS OF RESTRAINT. 

Many of the simple operations on the foot, such as the probing of a sinus, the paring out of corns, or the searching of pricks, may most suitably beperformed with the animal's leg held by the operator as a smith holds itfor shoeing. According to the temperament of the animal, even the operationfor the removal of a portion of the sole, or the injection of sinuses withcaustics, may be carried out with the animal simply twitched. 

When the operation is still a simple one, casting inconvenient orimpossible, and the animal restive, the twitch must be supplemented by someother method. The most simple and one of the most effective is the blind, cap, or bluff (Fig. 38). With it the most vicious animal or the mostnervous is in many instances either cowed into submission or soothed intoquietness. 

At the same time, more forcible means than the operator's own strengthmust be taken to hold the animal's foot from the ground. If the foot is afore-foot, and the point desired to be operated on is to the outside, thepastern should be firmly lashed to the forearm by means of a thin, shortcord, or a leather strap and buckle. Much may then be done in the way ofparing and probing that would otherwise be impossible. 

[Illustration: Fig. 38--The BLIND. ]

[Illustration: Fig. 39--THE SIDE-LINE. ]

If the foot is a hind one, one of the many methods of using what istermed by Liautard, in his 'Manual of Operative Veterinary Surgery, ' theplate-longe, must be adopted. This, in its most useful form, is a length ofclosely-woven cotton webbing, from about 2 to 2-1/2 inches wide, and from 5to 6 yards long, provided with a small loop formed on one of its ends, andperhaps better known to English readers as a 'side-line. ' If webbing be notavailable, a length of soft cotton rope, or a rope plaited and sold for thepurpose, as Fig. 39, will serve equally well. One of the most convenientmethods of using the side-line for securing the hind-foot is depicted inFigs. 40 and 41. 

[Illustration: FIG. 40. --THE SIDE-LINE ADJUSTED PREPARATORY TO SECURING THENEAR HIND-FOOT. ]

[Illustration: FIG. 41. --THE NEAR HIND-FOOT SECURED WITH THE SIDE-LINE. ]

Here the side-line has formed upon it a loop sufficiently large to form acollar. This is placed round the animal's neck, the free end of the linerun round the pastern of the desired foot, and the foot drawn forward, asin Fig. 40. 

The loose end of the line is then twisted once or twice round the tightportion, and finally given to an assistant to hold (see Fig. 41). The footis thus held from the ground, and violent kicking movements prevented. 

Where the operation is a major one, restraint of a distinctly more forciblenature becomes imperative. Many of the more serious operations can mostadvantageously be performed with the patient secured in some form or otherof stock or trevis, and the foot suitably fixed. It is not the good fortuneof every veterinary surgeon, however, to be the lucky possessor of one ofthese useful aids to successful operating. Perforce, he must fall back oncasting with the hobbles (Fig. 42). 

[Illustration: FIG. 42. --CASTING HOBBLES. ]

With the use of these we will assume our readers to be conversant, and willimagine the animal to be already cast. It remains, then, but to detail themost suitable means for firmly fixing the foot to be operated on. 

Here the side-line is again brought into use. Care should previously havebeen taken when casting to throw the animal so that the portion of the footto be operated on, whether inside or outside, falls uppermost, and that thebuckle of the hobble on that particular foot is placed so that it also iswithin easy reach when the animal is down. 

In the case we are illustrating the point of operation was the outside ofthe near hind coronet. We will, therefore, describe the mode of fixing thenear hind-foot upon the cannon of the near fore-limb. 

[Illustration: FIG. 43. --PHOTOGRAPH ILLUSTRATING METHOD OF ADJUSTING THESIDE-LINE PREPARATORY TO FIXING THE HIND-LEG UPON THE FORE. ]

The side-line is first adjusted as follows: It is fixed upon the cannon ofthe near hind-leg (A) by means of its small loop. From there it is passedunder the forearm of the same limb, over the forearm, under the roperunning from A to B; from there over and under the thigh, to be finallybrought in front of the thigh, and below the portion of rope running fromarm to thigh. The loose end of the side-line is then given to an assistantstanding behind the animal's back, the buckle of the hobble restraining thefoot unloosed, and strong but steady traction brought to bear from behindupon the line. The operator should now stand in front of the fore-limbs, and, by placing a hand on the rope passing round the arm, prevent the linefrom slipping below the knee. 

By this means the hind-limb is pulled forward until the foot projectsbeyond the cannon of the front-limb. When that position is reached, theoperator grasps the hock firmly with one hand, and, directing the side-lineto be slackened, gently slides downward the coils of rope round the armand thigh until they encircle the cannons of both limbs. The cannon of thehind-limb is firmly lashed to the cannon of the fore, and the foot firmlyand securely fixed in the best position for operating (see Fig. 44). 

[Illustration: FIG. 44. --PHOTOGRAPH SHOWING THE NEAR HIND-FOOT SECURED UPONTHE CANNON OF THE NEAR FORE-LIMB. ]

Similarly, with the horse still on his off side, the off hind-limb may befixed to the near fore, and the near fore and the off fore to the nearhind. 

With the animal on his near side, we may fix the near hind and the off hindto the off fore, and the off fore and near fore to the near hind. 

The points to be remembered in fixing the limbs thus are: (1) The side-lineshould always commence upon the cannon of the limb to be operated on; (2)it should next pass under and over (or over and under, it is immaterialwhich) first the arm and then the thigh, or the thigh and the arm, as thecase may be; (3) in every case, whether rounding the thigh and the arm fromabove or below, the piece of rope completing the round should always finishbelow that portion preceding it, so that traction upon it from behind theanimal's back should tend to keep all portions of it from slipping belowthe knee and the hock. 

With the uppermost fore-limb secured to the hind-limb in the manner we havedescribed, we have the underneath fore-limb suitably exposed for both thehigher and lower operations of neurectomy. The position for this operationwill be made better still if the lowermost limb (the one to be operated on)is removed from the hobbles and drawn forward by an assistant by means of apiece of rope fastened to the pastern. 

Taking what we have described as a general guide, other modifications ofthus securing the foot will suggest themselves to the operator to meet thespecial requirements of the case with which he is dealing. 

Regarding the administration of chloroform, no description of the methodis needed here, as it will be found fully detailed in most good works ongeneral surgery. Where great immobility is needed, it is one of the mostvaluable means of restraint we have. Apart from that, its use in anyserious operation is always to be advocated, if only on the score of humaneconsideration for the dumb animal helpless under our hands. 

B. INSTRUMENTS REQUIRED. 

In addition to those required for operations on the softer structures--suchas scalpels, forceps, artery forceps, directors, scissors, etc. --thesurgery of the foot demands instruments specially adapted for dealing withthe horn. 

A great deal will depend upon the operator as to whether these are few ormany. The average man of resource will deem a smith's rasp and one or twostrong drawing-knives amply sufficient, and on no account should they beomitted from the list of those ready to hand. 

[Illustration: FIG. 45. --THE ORDINARY DRAWING-KNIFE. ]

The ordinary smith's drawing-knife (Fig. 45) is well known to almosteveryone, and is well suited for much of the rougher part of the work. The careful following up of pricks, however, and some of the more specialoperations demanding removal of portions of the lateral cartilages call forinstruments of a more delicate character and peculiar construction. Theseare to be found in the so-called sage-knife, and the modern (French)pattern of drawing-knife. 

[Illustration: FIG. 46. _a, b_, Modern forms of drawing-knife; _c, d, e_, sage-knives. ]

The modern drawing-knife differs from the smith's instrument in beingattached to a straight, instead of a curved, handle, and in usually beingsharp on both edges instead of only on one. These are made in various sizes(Fig. 46, _a, b_), and the blades flat, curved on the flat, or curved at anangle with the edges of the haft. 

The sage-knife, as its name indicates, is a knife with a lanceolate-shapedblade. These also may be obtained in varying forms and sizes (Fig. 46, _c, d, e_). Fig. 46, _c_, is a single-edged, right-handed sage-knife. Fig. 46, _d_, is a left-handed instrument of the same type. The double-edgedsage-knife is represented in Fig. 46, _e_. 

[Illustration: FIG. 47. --SYMES'S ABSCESS-KNIFE. ]

It may be mentioned too, in passing, that the ordinary Symes'sabscess-knife (Fig. 47) is a most useful instrument when performing theoperation of partial excision of the lateral cartilages, its peculiar shapelending itself admirably to the niceties of the operation. 

One or two good-shaped firing-irons will also be found useful. They willlighten the labour of tediously excavating grooves with the knife, where that procedure is necessary; and, used in certain positions to beafterwards described, will afford just that necessary degree of stimulus tothe horn-secreting structures of the foot, which the use of the knife alonewill not. 

The man in country practice will also be well advised in carrying to everyfoot case a compact outfit, such as that carried by the smith. This willconsist of hammer and pincers, drawing-knife and buffer. Much valuable timeis then often saved which would otherwise be wasted in driving round forthe nearest smith. 

There are other special operations requiring the use of specially-devisedinstruments for their successful carrying out. These we shall mention whenwe come to a consideration of the operations in which they are necessary. 

C. THE APPLICATION OF DRESSINGS. 

One of the most common methods of applying a dressing to the foot ispoulticing. Usually resorted to on account of its warmth-retainingproperties, the poultice may also be medicated. In fact, a poultice, strongly impregnated with perchloride of mercury or other powerfulantiseptic, is a useful dressing in a case of a punctured foot, or awise preliminary to an operation involving the wounding of the deeperstructures. The poultice may consist of any material that serves to retainheat for the longest time. Meal of any kind that contains a fair percentageof oil is suitable. Crushed linseed, linseed and bran, or linseed-cake dustare among the best. 

To prepare it, all that is necessary is to partly fill a bucket with thematerial and pour upon it boiling water. The hot mass is emptied into asuitable bag, at the bottom of which it is wise to first place a thin layerof straw, in order to prevent the bag wearing through, and then securedround the foot. This is generally done by means of a piece of stout cord, or by straps and buckles fastened round the pastern and above the fetlock. 

An improved method of fastening has been devised by Lieutenant-ColonelNunn:

'A thin rope or stout piece of cord about 5 feet long is doubled in two, and a knot tied at the double end so as to form a loop about 5 or 6 incheslong, this length depending on the size of the foot (as at A, Fig. 48). Thepoultice or other dressing is applied to the foot, and the cloth wrappedround in the ordinary way, the loop of the cord being placed at the back ofthe pastern (as in A, Fig. 49); the ends of the cord are passed round, oneon the inside and the other on the outside, towards the front (as in B, Fig. 49). These ends are then twined together down as far as the toe (see Cin Fig. 49). The foot is now lifted up, and the ends of the cord (CC, Fig. 49), are passed through the loop A (as at D, Fig. 49), and then drawntight. The ends of the cord are now separated, and carried up to thecoronet (as at EE, Fig. 49), one on the outside, the other on the inside ofthe foot. They are then again twisted round each other once or twice (as atF, Fig. 50), and are passed round the pastern once or twice on each side. They are now passed under the cord (E, Fig. 49), and then reversed, soas to tighten up E, and are finally tied round the pastern in the usualmanner. The arrangement of the cords on the sole is shown in Fig. 51, whichis a view from the posterior part. 

[Illustration: FIGS. 48, 49, 50, 51. --ILLUSTRATING LIEUTENANT-COLONELNUNN'S METHOD OF APPLYING A POULTICE TO THE FOOT. ]

'The advantages of this method of fastening have been found to be: (1) Itdoes not chafe the skin; (2) if properly applied it has never been knownto come undone; (3) it is the only way we know that a poultice can besatisfactorily applied to a mule's hind-foot; (4) horses can be exercisedwhen the poultice is on the foot, which is almost impossible with theordinary leather boot; (5) the sacking or canvas does not cut through soquickly. '

[Illustration: FIGS. 52, 53. --TWO FORMS OF POULTICE-BOOT. ]

A further method of applying the poultice is by using one of thepoultice-boots made for that purpose (see Figs. 52 and 53). 

These have an objection. They are apt to be allowed to get extremely dirty, and so, by carrying infective matter from the foot of one animal to that ofanother, undo the good that the warmth of the poultice is bringing about. The advantage of the ordinary sacking or canvas is that it may be castaside after the application of each poultice. Where the boot is kept clean, however, it will save a great deal of time and trouble to the attendant. 

While on the subject of poulticing, it is well to remark that in many casesit may be more advantageous to supply the necessary warmth and moisture tothe foot by keeping it immersed in a narrow tub of water maintained at therequired temperature. By this means the warmth is carried further up thelimb (sometimes an important point), and the water can more conveniently bemedicated with whatever is required than can the poultice. In fact, it isthe author's general practice, where the attendants can be induced to takethe necessary pains, to always advise this latter method. 

[Illustration: FIG. 54. --SWAB FOR APPLYING MOISTURE TO THE FOOT. ]

Where a dressing is relied upon by some practitioners on account of thewarmth it gives, others, even in identical cases, will depend upon theeffects of cold. This may be applied by means of what are called 'swabs. 'In their simplest form swabs may consist only of hay-bands or severallayers of thick bandage bound round the foot and coronet, and kept cool byhaving water constantly poured upon them. In many cases the form of swabdepicted in Fig. 54 will be found more convenient. 

When only one foot is required to be dressed, and a water-supply isavailable, by far the preferable method is to attach one end of a lengthof rubber tubing to the water-tap, and fasten the other just above thecoronet, allowing the water to trickle slowly over the foot. In cases wherea forced water-supply is unobtainable, and the case warrants the extratrouble, much may be done with a medium-sized cask of water placedsomewhere over the animal, and the rubber tubing connected with that. 

Where the dressing is desired to be kept applied to the sole and frog only, there is no method more satisfactory than the shoe with plates. 

[Illustration: FIG. 55. --THE SHOE WITH PLATES. _A_, The plates in position;_B_, the plates separated from the shoe. ]

[Illustration: FIG. 56. --THE QUITTOR SYRINGE. ]

The plates are of metal, preferably of thin sheet iron or zinc, and areslipped between the upper surface of the shoe and the foot after the mannershown in Fig. 55. The plates themselves are shaped as depicted in Fig. 55, _a, b, c, a_ and _b_ curved to meet the outlines of the shoe, and _c_shaped so as to wedge tightly over the posterior ends of the side plates, and between them and the shoe. A distinct advantage of the plate method ofdressing is that a certain amount of pressure may be maintained on the soleand frog, a very important consideration in connection with some of thediseases with which we shall later deal. 

When dealing with sinuous wounds of the foot, another favourite mode ofapplying dressings is by means of the syringe, and no better instrument forall cases can be found than that known as a quittor syringe (Fig. 56). 

A further mode of applying dressing, and one frequently practisedin connection with the foot, is known as 'plugging. ' This is almostsufficiently indicated by its name. It consists in rolling portions ofthe dressing into little cylinders, wrapped round with thin paper, andintroduced into a sinus or other position where considered necessary. 

D. PLANTAR NEURECTOMY. 

As a last resort in the treatment of many diseases of the foot theoperation of neurectomy is often advised. It will be wise, therefore, toinsert a description of the operation here. 

_Derivation of the Word_. --For many years the operation was known simply as'nerving' or 'unnerving, ' and it was not until 1823, at the suggestionof Dr. George Pearson, that Percival introduced the word _neurotomy_to signify the operation with which we are now about to deal. The wordneurotomy, however, used strictly, means the act or practice of dissectionof nerves, and, when applied to the operation as practised to-day, describes only a step in the procedure. 

As the operation really consists in cutting down upon, and afterwardsexcising a portion of the nerve, the modern appellation of_neurectomy_--from the Greek _neuron_, a nerve; and _tome_, a cutting, signifying the cutting out of a nerve or the portion of a nerve--is farmore suitable. 

According as the nerve operated on is the plantar or the median, theoperation is known as plantar or median neurectomy. 

_History of the Operation_. --It is to two English veterinarians that weowe the introduction of the operation to the veterinary world. In 1819Professor Sewell announced himself as the originator of neurotomy. Thisclaim was disputed by Moorcraft, who appears to have successfullyshown himself to be the real person entitled to that honour, he havingsatisfactorily performed the operation on numerous animals for fullyeighteen years prior to Professor Sewell's announcement. It appears thatMoorcraft left this country for India in 1808, having practised theoperation in more or less obscurity for some six or seven years previousto that. After his departure neurectomy, as introduced by him, either diedaway in repute, or was not made by him sufficiently public to become amatter of general knowledge. To Professor Sewell, therefore, although notthe actual originator of the operation, belongs the honour of making itpublic to the veterinary profession. 

In 1824, five years after Sewell's introduction, we find it practised onthe Continent by Girard. We gather, however, from the writings of Percivaland Liautard, that both in this country and on the Continent the operationwas for several years largely in the stage of experiment. Unsuitablesubjects were operated on; the work afterwards given to the animalimproperly adjusted to his altered condition; and the bad after-results ofthe operation almost ignored by some, and greatly exaggerated by others. In fact, some long time elapsed before veterinary surgeons allotted to theoperation that measure of credit which the results following it warranted. 

_The Object of the Operation_ is to render the foot insensitive to pain, and to give to an otherwise incurably lame animal a further period ofusefulness. After the operation, as time goes on, this object may becomedefeated by the reunion of the divided ends of the nerve. In that case, neurectomy must necessarily be performed again. 

_The Operation_. --Two forms of neurectomy are recognised--the highoperation and the low. The low operation deals with the posterior digitalbranch of the plantar nerve, and the high operation with the plantaritself. 

It is the latter operation with which we shall deal first. In our opinionit is that most likely to be followed by satisfactory results. The areasupplied by the posterior digital is mainly the posterior portion of thedigit. Thus, unless the cause of the lameness is diagnosed with certaintyto be situated somewhere in the posterior region of the foot, section ofthe posterior digital alone will not give total insensibility to pain. Added to that, we may remember this: Below the point at which the digitalsbranch off from the plantar there is always more likelihood of the partwe are attempting to render insensible being supplied by another andadventitious branch, or a branch that, as regards its direction, isabnormally distributed. As a last consideration, we may say that the higheroperation is the easier to perform. 

Percival, in his works on lameness, has some very sage remarks to make byway of a preliminary, and we cannot do better than quote them here. Hesays:

'To command success in neurectomy three considerations demand attention:

'1. The subject must be fit and proper; in particular, the disease forwhich neurectomy is performed should be suitable in kind, seat, stage, etc. 

'2. The operation must be skilfully and effectually performed. 

'3. The use that is made of the patient afterwards should not exceed whathis altered condition appears to have fitted him for. 

'The veterinarian who is guided by considerations such as those will findthat he has restored to work horses who would otherwise have been utterlyuseless. A plain and safe argument wherewith to meet the objections toneurectomy is simply to ask the question what the animal is worth, or towhat useful purpose he can be put, that happens to be the subject of suchan operation. 

'If the horse can be shown to be still serviceable and valuable, then he isnot a legitimate subject for the operation. The rule of procedure I havelaid down is to operate on no other but the _incurably lame horse_; andwhenever this has been attended to, not only has success been the morebrilliant, but indemnification from blame or reproach has been assured. '

_Preparation of the Subject_. --But little in the way of medicinalpreparation is necessary. When the animal is a gross, heavy feeder, andcarries a more than ordinary amount of cupboard, all that is needed is towithhold his usual allowance of food for some time prior to the operation, simply to avoid risk of rupture when casting. If considered advisable, adose of physic may also be administered. 

To the seat of operation, however, careful attention should be given. Onthe day previous to the operation the hair should be closely removed withthe clipping machines, and the skin thoroughly cleansed with warm waterand soap. After this, a bandage soaked in a 4 per cent, watery solutionof carbolic acid should be wrapped lightly round the limb, and allowed toremain in position until the animal is cast and ready for the operation thefollowing morning. On removing the bandage prior to operating, the partshould again be bathed with a cold 5 per cent. Solution of carbolic acidand swabbed dry. Attention to these details will serve to leave the woundin that favourable condition in which it heals nicely, and with the minimumamount of trouble. 

_Preliminary Steps_. --By some practitioners the operation is performed withthe animal standing, local anæsthesia having been first obtained by the useof cocaine, or an ethyl chloride spray. There is no gainsaying the fact, however, that the operation of neurectomy is a painful one, and that, withmost operators, success will be more fully guaranteed with the animal castand the limb held in a suitable position by an assistant. 

The animal is thrown by the hobbles upon the side of the leg which is to beoperated on. The cannon of the upper fore-limb is then fixed to the cannonof the upper hind, as described under the section of this chapter devotedto the methods of restraint, and the lower limb freed from the hobbles anddrawn forward by an assistant by means of a stout piece of cord round thepastern. 

An alternative method of holding the limb is to bind both fore-legstogether above the knee by means of the side-line run round a few times inthe form of the figure 8, and then fastened off. As in the former method, the lower foot is then removed from the hobble, and again held forward byan assistant. By either method the inside of the limb is operated on first. 

[Illustration: FIG. 57. --THE ESMARCH RUBBER BANDAGE AND TOURNIQUET. ]

Although it is not absolutely necessary, it is an advantage, especially tothe inexperienced operator, to apply before operating an Esmarch's bandageand tourniquet (Fig. 57). This expels the greater part of the blood fromthe limb, and renders the operation comparatively bloodless. 

[Illustration: FIG. 58. --RUBBER TOURNIQUET WITH WOODEN BLOCK. ]

The Esmarch bandage is composed of solid rubber, and with it the limb isbandaged tightly from below upwards. On reaching the knee the tourniquet isstretched round the limb, fastened by means of its buckle and strap, andthe bandage removed. Those who feel they can dispense with the bandage usethe tourniquet alone. For this purpose the form depicted in Fig. 58, andthe one in general use at the Royal Veterinary College, is more suitable, on account of its wooden block, which may be placed so as to press on themain artery of supply. 

[Illustration: Fig. 59. NEURECTOMY BISTOURY. ]

_Instruments Required_. --These should be at hand in an earthenware orenamelled iron tray containing just sufficient of a 5 per cent. Solutionof carbolic acid to keep them covered. Those that are necessary will be asharp scalpel, or, if preferred, one of the many forms of bistoury devisedfor the purpose (see Fig. 59), a pair of artery forceps, a needle readythreaded with silk or gut, one of the patterns of neurectomy needle (seeFig. 60), and a pair of blunt-pointed scissors curved on the flat. It isalso an advantage, when once the incision through the skin is made, toemploy one of the forms of elastic, self-adjusting tenacula (see Fig. 61)for keeping the edges of the wound apart while searching for the nerve. 

[Illustration: FIG. 60. NEURECTOMY NEEDLE. ]

_Incision through the Skin_. --We remember that the plantar nerve of theinner side is in close relation with the internal metacarpal artery, andthat both, in company with the internal metacarpal vein, run down the limbin close proximity with the inner border of the flexor tendons. Also, weremember that the external plantar nerve has no attendant artery, although, like its fellow, it is to be found in close touch with the edge of theflexor tendons. 

Bearing these landmarks in mind, we feel for the nerve in the hollowjust above the fetlock-joint by noting the pulsations of the artery, anddetermining the edge of the flexor tendons. This done, a clean incision ismade with the bistoury or the scalpel in the direction of the vessels. Theincision should be made firmly and decisively, so that the skin may becleanly penetrated with one clear cut. If judiciously made, little else inthe shape of dissection will be needed. 

[Illustration: FIG. 61. --DOUBLE TENACULUM. ]

It is now that the double tenaculum (Fig. 61) is applied. One clip is fixedto the anterior edge of the wound, and the other carried beneath the limband made to grasp the posterior edge. If found desirable to keep theedges of the wound apart, and no tenaculum to hand, the same end may beaccomplished by means of a needle and silk. In like manner as is thetenaculum, the silk is attached to one edge of the wound, carried under thelimb, and firmly secured to the other. 

Having made the incision, the wound should be wiped free from blood bymeans of a pledget of cotton-wool previously soaked in a carbolic acidsolution and squeezed dry. At the bottom of the wound will now be seenthe glistening white sheath, containing the vein, artery, and nerve. Thisshould be picked up with the forceps, and a further incision made with thebistoury. Care should be exercised in making this second incision, or theartery may accidentally be opened. If an ordinary scalpel is used, thelower end of the sheath should be picked up and the point of the scalpelinserted through it. With the cutting edge of the scalpel turned towardsthe opening of the wound, the sheath is then slit from below upwards. Thesecond incision satisfactorily made, the wound is again wiped dry, and thenerve seen as a piece of white, curled string in the posterior portion ofthe wound. 

At this stage it is advisable to accurately ascertain whether what we havetaken to be the nerve actually is it. This is done by taking it up with theforceps and giving it a sharp tweeze. A sudden struggle on the part of thepatient will then leave no doubt in the operator's mind that it is thenerve he has interfered with. 

_Section of the Nerve_. --The neurectomy needle (Fig. 60) is now taken, and, excluding the other structures, passed under the nerve. A piece of stoutsilk or ordinary string is then threaded through the eye of the needle, theneedle withdrawn, and the silk left in position under the nerve. The silkis now tied in a loop, and the nerve by this means gently lifted from itsbed. With the curved scissors or the scalpel it is severed as high up as ispossible. The lower end of the severed nerve is then grasped firmly withthe forceps, pulled downwards as far as possible, and then cut off. Atleast an inch of the nerve should be excised. 

The animal is then turned over, and the opposite side of the limb operatedon in the same manner. 

The tourniquet is now removed, and the wound is examined for bleedingvessels. If the hæmorrhage is only slight, the wound should be merelydabbed gently with the antiseptic wool until it has stayed. A larger vesselmay be taken up with the artery forceps and ligatured, or the hæmorrhagestopped by torsion. On no account, unless it it done to stay hæmorrhagethat is otherwise uncontrollable, should the wound be sutured with blood init. With the wound once dry and clean, it is well to insert three or foursilk sutures, but care must be taken not to draw them too tightly. Thisdone, the patient may be allowed to get up. _After-treatment_. --This issimple. Over each wound is placed a pledget of antiseptic cotton-wool ortow, and the whole lightly covered with a bandage soaked in an antisepticsolution. For the first night the animal should be tied up short to therack, and the following morning the bandages removed. A little boracicacid or iodoform, or a mixture of the two combined with starch (starch andboracic acid equal parts, iodoform 1 drachm to each ounce) should now bedusted over the wounds, the antiseptic pledgets renewed, and the bandagereadjusted over all. 

At the end of three or four days the bandages may be dispensed with. Allthat is necessary now is an occasional dusting with an antiseptic powder, and, as far as possible, the restriction of movement. At the end of a weekthe sutures may be removed, and the animal turned into a loose box or outto pasture. 

E. MEDIAN NEURECTOMY. 

As a palliative for lameness when confined to the foot, one would imaginethat the plantar operation would be all sufficient. There are operators, however, who state that the results following section of the median nervehave been such as to cause them to entirely abandon the lower operation inits favour. If only for that reason a brief mention of the operation mustbe made here. 

The operation was first performed in this country in October, 1895, thesubject being one of the out-patients at the Royal Veterinary College FreeClinique. 

For five or six years following this date Professor Hobday performed theoperation some several hundred times, and was certainly instrumental inbringing the operation into prominence. Though so recently introduced here, it appears to have been practised for several years on the Continent, originating in Germany as early as 1867. In that country a first publicaccount of it was published in 1885 by Professor Peters of Berlin, while inFrance it was introduced by Pellerin in 1892. In this operation a portionof the median nerve is excised on the inside of the elbow-joint just belowthe internal condyle of the humerus. Here the nerve runs behind the artery, then crosses it, and descends in a slightly forward direction behind theridge formed by the radius. 

The position of the limb most suitable for the operation is exactly that wehave described as most convenient for the plantar excision. The animal iscast, preferably anæsthetized, and the limb removed from the hobbles, andheld as far forward as is possible by an assistant with the side-line. 

Professor Hobday's description of the operation is as follows:

'A bold incision is made through the skin and aponcurotic portion ofthe pectoralis transversus and panniculus muscles, about 1 to 3 inches(depending on the size of the horse) below the internal condyle of thehumerus, and immediately behind the ridge formed by the radius. Thislatter, and the nerve which can be felt passing over the elbow-joint, formthe chief landmarks. The hæmorrhage which ensues is principally venous, andis easily controlled by the artery forceps. In some cases I have found itof advantage to put on a tourniquet below the seat of operation, but thisis not always advisable, as it distends the radial artery. We now haveexposed to view the glistening white fascia of the arm, which must beincised cautiously for about an inch. This will reveal the median nerveitself situated upon the red fibres of the flexor metacarpi internusmuscle. If not fortunate enough to have cut immediately over the nerve, itcan be readily felt with the finger between the belly of the flexor muscleand the radius. '[A]

[Footnote A: _Journal of Comparative Pathology and Therapeutics_, vol. Ix. , p. 181. ]

The nerve exposed, the remainder of the operation is exactly as thatdescribed in removing the portion of the nerve in the plantar operation. The wound is sutured and suitably dressed, and a fair amount of exerciseafterwards allowed the patient. 

F. LENGTH OF REST AFTER NEURECTOMY. 

This is placed by the majority of surgeons at about three weeks to amonth. Within that period no excessive exertion should be undergone bythe patient. A certain amount of quiet exercise, however, is beneficial, facilitating the healing of the wounds, and accustoming the animal to thealtered condition of his limb. 

G. SEQUELÆ OF NEURECTOMY. 

These we shall relate collectively, making no distinction between thosefollowing excision of the plantar nerve and those succeeding section of themedian. It must be remembered by the surgeon, however, that the unfortunatesequelæ we are now about to describe are likely to be far more grave whenfollowing section of the larger nerve. 

_Liability of Pricked Foot going undetected_. --On account of the warningthey convey to the surgeon, first place among the sequelæ of neurectomymust be given to accidents following loss of sensation. Take, for example, punctured foot. In any case, in the sense of being unforeseen, it isaccidental. In the neurectomized foot it becomes doubly accidental, in thatnot only is it unforeseen, but that it is for some time indiscoverable. With the foot deprived of sensation, a nail may be picked up, or a pricksustained at the forge, and no intimation given to the attendant until pushas underrun the horn, and broken out at the coronet. What follows, then, is that the hoof as a whole, or the greater part of it, sloughs off. 

No neurectomy should be undertaken unless this contingency has been allowedfor. The owner should be advised of it by the surgeon, who should at thesame time enjoin on his client the absolute necessity of giving to theneurectomized foot daily and careful attention. 

_Loss of Tone in the Non-sensitive Area_. --In addition to the mischiefresulting from a wound going undetected, it must be remembered that theloss of tone resulting from the operation gives to every wound (howeverslight), in the region supplied by the removed nerve, a sluggish andtroublesome character. Difficult to deal with as wounds about the footordinarily are, they are rendered more so by a previous neurectomy. 

_Gelatinous Degeneration_. This is a condition liable to occur in caseswhere the operation has been too long deferred, and when considerablestructural alteration has already taken place in the shape of diseased boneor tendon, more especially in navicular disease. It consists in a peculiarsoftening of the structures of the limb, accompanied with enlargement, due to swelling of the connective tissues, the enlargement and softeninggenerally making itself first apparent by a soft, pulpy swelling in thehollow of the heel. 

From this onwards the enlargement increases, and lameness becomesexcessive, the animal going more and more on his heels, until, finally, noportion of the solar surface of the foot comes to the ground at all. 

The case is hopeless, and destruction should be advised. 

_Reported Case_. --'The patient, a brown carriage gelding, was brought tothe Royal Veterinary College infirmary in a cart on December 31, the onlyprevious history obtainable being that it had suddenly fallen lame a monthbefore. 

'The symptoms presented were excessive lameness of the near fore-limb. Onbeing trotted, the toe was elevated each time the foot reached the ground, progression being entirely on the heels. Separation of the hoof for about 2inches at the hinder part of the coronet; oedematous swelling from foot toknee, extending during the next three days to the elbow. Great tendernessbetween the knee and the fetlock; below this no sensation whatever, as apin was inserted in several places round the coronet without causing anysymptoms of pain. On further examination, two unnerving scars were found. No treatment was adopted, and the horse was destroyed on January 6. 

'On dissecting the leg, the following appearances presented themselves:

'The limb was very much enlarged, due to thickening of the connectivetissue, the skin being removed only with difficulty. The tendons were softand much thickened. A rupture of the skin at the coronet, just where theskin meets the wall of the foot. Large extravasations of blood at the backof the tendons, situated in the lower half. _External_ nerve trunk hadbecome reunited, at the point of junction there being a hard lump aboutthe size of a walnut. _Internal_ nerve trunk also had become reunited, andpresented a thickened portion at the point of junction, but not so large asthat of the outer side, and situated in the lower half of the tendon, about2 inches higher than that on the external nerve. This nerve trunk wasatrophied below the thickening, and had undergone gelatinous degeneration. Judging from the scars on the skin, this side had evidently been unnerved aweek or ten days previously to that on the outer side. The band stretchingacross the back of the perforatus, between the external and internalnerves, appeared on the inside to have become firmly fixed into the tendon. 

'On removing the hoof, under the sole there appeared a large quantity ofvery foetid pus; the laminæ were very much inflamed in patches. Therewas an enormous thickening of connective tissues in the heel. On cuttinglongitudinally through the perforatus tendon, there was exposed a largeblood-coloured mass, of a gelatinous appearance, situated on the perforatustendon, the latter being very much thickened, and growing to the navicularbone. The underneath surface of the superior suspensory ligament was muchthickened, and firmly adherent to the bone; at the posterior surface ofthe metacarpus there was a quantity of gelatinous substance. The anteriorligament of the fetlock-joint was thickened; the navicular bone was entire, but showed lesions of navicular disease, being ulcerated. Section throughthe bone did not reveal anything further. It may be here remarked that theulcerations were on either side of the central ridge, and not at all on theridge itself. 

'Microscopic examination of the tissue joining the two ends of the nervetogether revealed a few nerve fibres; the general appearance was thatof granulation tissue, containing capillary vessels, which were fairlyplentiful, and comparatively large in size. '[A]

[Footnote A: _Veterinary Record_, vol. Iv. , p. 386 (Hobday)]

_Chronic Oedema of the Leg_. --In some cases there is a distinct swellingof the leg some time after the operation. This exposes the limb to theinfliction of sores from striking with the opposite foot, with, of course, the difficulty in healing we have just described. 

_Persistent Pruritus_. --This annoying sequel occurs in the neurectomizedlimb, with or without gelatinous degeneration, and appears to be without aremedy. The itching in some cases is so intense as to lead the animal toconstantly gnaw at the top of the foot. As one observer has remarked, theanimal may begin literally biting pieces out of his limb. The result of theirritation and gnawing is fatal. Great sloughing of the parts takes place, and the animal has eventually to be slaughtered. 

_Fracture of the Bones_. --The sudden loss of sensation in a foot may causethe animal to use violently the limb he has for months past been carefullynursing. It may be that the lameness for which the operation has beenperformed has been due to disease existing in the navicular bone, andextending, perhaps, to the os pedis. By the disease the bone has alreadybeen made brittle, its substance and ligamentous attachments perchanceweakened and broken up by a slow-spreading caries, and rarefaction of theremaining bone substance rendered almost certain. In this instance, thefree use of the foot, and the application to the diseased structures of anunwonted pressure immediately after the operation results in fracture. Withthe rupture of the structures we get the elevated toe and soft swelling inthe heel, as described in gelatinous degeneration. Treatment, of course, isout of the question. 

_Neuroma_. --A further sequel is the appearance at the seat of the operationof what is termed an 'amputational neuroma. ' This is a tumour-likegrowth occurring on the end of the divided nerve. It is composed ofconnective-tissue elements permeated by nerve fibres which have grown outfrom the axis-cylinders of the nerve stump. It may vary in size from a peato a hazel-nut, and is frequently the cause of much pain. This must be cutdown upon and cleanly removed, taking away at the same time as much of thenerve as is possible. 

_Reunion of the Divided Nerve_. --We may say at once that 'reunion' in thepopular sense of the word does not take place. At a varying period aftersection, however, we do get a return of sensation. This is brought about inthe following manner: The axis-cylinder of the nerve, still in connectionwith the spinal cord, swells somewhat, and hypertrophies. The cells of thishypertrophied portion show a great tendency to proliferate and producenew nerve structure. This growing point splits, and gives rise to severalfibrils, which are new axis-cylinders. These commence to grow towards theperiphery, and, in so doing, grow through the cicatricial tissue that hasformed at the seat of the operation. 

After passing through the cicatricial tissue (the amount of which tissue, of course, controls the length of time that insensibility remains), thegrowing axis-cylinders reach the degenerated portions of the nerve belowthe point of section. It is along the track of the old nerve that the newgrowths from the stump reproduce themselves. 

The fact of the new growths having to pass through the fibrous tissue ofthe cicatrix before they can gain the course of the old nerve, along whichlatter their progress of growth is comparatively easy, affords ampleillustration that as large a portion as is possible of the nerve should beremoved when operating, in order to convey insensibility for the longesttime. After reunion, of course, nothing remains but to repeat theoperation. 

_The Existence of an Adventitious Nerve-supply_. --While not exactly asequel of the operation, the fact that it is not discovered until after theoperation has been performed warrants us in mentioning it here. It isnot an uncommon thing in the lower operation to find that sensation andsymptoms of lameness still persist after section of the nerve. In manycases this has been traced to the existence of an abnormal nerve branch. In the higher operation this is not so likely to be met with. That it mayoccur, however, is shown by the following interesting case related byHarold Sessions, F. R. C. V. S. :[A]

[Footnote A: _Journal of Comparative Pathology and Therapeutics_, vol. Xii. , p. 343. ]

'In June of 1898 I saw a hunter suffering from navicular disease. Aftercarefully examining the leg, I advised the owner to have the operation ofneurectomy performed upon him. This he decided to do, and the horse wassent to me about the beginning of July. 

[Illustration: FIG. 62. --DISSECTED EXTERNAL METACARPAL NERVE AND BRANCHES. _a_, Metacarpal; _b_, anterior plantar; _c_, extra branch (probably fromthe internal metacarpal), conveying sensation after division of theexternal metacarpal. ]

'The operation was performed in the ordinary way, without any difficultywhatever. The wounds healed nicely, but the horse still continued to golame. Careful examination showed that there was still sensation on theoutside of the foot. Thinking that possibly there might be two externalmetacarpal nerves, the horse was again cast, the operation being performedslightly lower down. Only the main branch of the external metacarpal nervecould be found. A piece of this was taken out, and the horse let up. Onexamination, sensation was still found in the posterior part of the outsideof the foot. It was very evident that there was some abnormal distributionof the nerve, as sensation was still being conveyed to that part of thefoot. 

'As the horse was absolutely useless, and would have to be shot unless thispiece of nerve could be found, he was again thrown, and after he had beenanæsthetized I determined to follow the course of the nerve down, until Ifound where the accessory branch came from. This I found a little below thefetlock, about 1/2 inch below the point where the anterior plantar nerve isgiven off from the metacarpal nerve. It was about 1/2 inch below the spotwhere the anterior plantar nerve passes between the artery and vein of thefoot, and it was somewhat difficult to get at it. 

'Fig. 62 shows the exact size and distribution of the nerves. After theseparation of the accessory branch, sensation was taken from the foot, andthe horse went perfectly sound. '

_Stumbling_. --In addition to the sequelæ we have mentioned, it is urgedagainst the operation of neurectomy that one of the first effects ofdepriving the foot of the sense of touch is a tendency on the part ofthe animal to stumble. From the cases we have seen we cannot regardthis objection as a serious one. Nevertheless, as veterinarians, with aknowledge of the physiology of the structures with which we are dealing, we must treat the objection with respect, for, after all, we are bound toallow that stumbling, and a bad form of it, would be but a natural sequenceof the operation we have just performed. The real fact remains, however, that cases of stumbling, even immediately after the operation, arerare; and that even when they do occur, the animal seems easily able toaccommodate himself to the altered condition, and as readily uses thecomparatively inert mass at the end of his limb as he did previously theintact foot. 

H. ADVANTAGES OF THE OPERATION. 

From the prominence we have given to the unfortunate sequelæ of theoperation it might possibly be inferred that, while not giving it ourabsolute condemnation, we regard neurectomy with a certain amount ofdistrust. That we may contradict any such false impression, we state herethat in many cases the operation is the only measure which will offerrelief from pain, and restore to work an otherwise useless animal. Insupport of that we will now quote the recognised advantages of theoperation. 

That in many cases, when all other methods--surgical and medicinal--havefailed, there is an immediate and total freedom from pain and lameness noone will deny. This, if it restores to active work an animal that wouldotherwise have had to have been cast aside, is ample justification forgiving the operation, in spite of its many unfortunate terminations, a realplace among the more highly favoured remedial measures to our hand. 

'For _Contracted Hoofs_, viewing them in the light of idiopathic disease, or as being the immediate cause of the existing lameness in the uninflamedcondition of the foot, and when consequential changes of its organism havetaken place which bid defiance to therapeutic measures, _neurotomy_ is a_warrantable resource_' (Percival). 

'For _Ringbone_ neurotomy has been practised with perfect success, afterblistering and firing had both failed, notwithstanding the work the animalhad to perform afterwards was of the most trying nature' (_ibid_. ). 

For _Navicular Disease_, when that malady is diagnosed, the earlierneurectomy is performed the better. The greater work given to the diseasedbursa and bone, and the return of the contracted heels to the normal, brought about by the greater freedom with which the foot is used, areclaimed by many to effect a cure. 

Writing of navicular disease, and mentioning his belief in the possibilityof the diseased bone effecting its own repair after the operation, HaroldLeeney, M. R. C. V. S. , says:

'The expansion of the heel, and rapid development of the frog (in this andmany other cases) immediately after the operation, has not, I venture tothink, attracted so much attention as it deserves, and may have somethingto do with those cases which appear to be actually _cured_, not merely madeto go sound by absence of pain. '[A]

[Footnote A: _Veterinary Record_, vol. Xi. , p. 297. ]

Speaking of the median operation before a meeting of the Central VeterinaryMedical Society, Professor Hobday says:[A]

[Footnote A: _Veterinary Record_, vol. Xiii. , p. 427. ]

'For old-standing lamenesses, when due to splints, exostoses, chronicallysprained, thickened, and painful perforans and perforatus tendons, or casesof that kind which cause pain by pressing on the adjacent nerve structures, after all other known methods have failed, median neurectomy is theoperation which will be most likely to give the animal a new lease of lifeand usefulness. '

'Of the _Humanity and Utility of Neurectomy_ there can be no questionwhatever, and provided the cases are well selected, and the operationis efficiently performed, the advantages to be derived from it are moststriking as well as enduring. But the disadvantages attending the loss ofsensation in the foot have been brought forward on many occasions asan argument against neurectomy, and no one can deny that the foot withsensation is better than one without that faculty. But in a long experienceof the operation I have never found these disadvantages outweigh the greatadvantages which have immediately followed it. '[A]

[Footnote A: _Veterinary Journal_, vol. Ix. , p. 178 (Fleming). ]

Beyond these, the direct advantages of neurectomy, are other and moreindirect advantages which claim attention. 

The most astonishing among them is the fact noted by many writers of reputethat exostoses (ringbones, side-bones, splints, etc. ) rapidly diminish insize. This is vouched for by such well-known authorities as Zundel andNocard. 

Percival, too, mentions at some length the effect of the removal of pain onthe oestral and generative functions, quoting a case of a brood cart-mareby reason of bony deposits being stayed from breeding for some years. Twomonths after the operation she went to work, and moved sound, her alteredcondition leading her to breed several healthy foals. 

I. THE USE OF THE HORSE THAT HAS UNDERGONE NEURECTOMY. 

No operation is of any considerable value to the veterinary surgeon unlesshe is able to show that after it he has left his patient workable. Thealleviation of pain alone, commendable as it is from a humanitarianstandpoint, is of no interest to the average owner of horse-flesh, unlesswith it he sees his animal capable of justifying his existence by theamount of labour performed. 

Criticised in this way, is the operation of neurectomy justifiable? Uponthat point the opinions of many practitioners, even at the present day, differ. We have already partly answered the objections likely to be raisedon this score by stating that the work afterwards allotted the animalshould be fixed to suit his altered condition. It may be taken as a generalrule that in all cases where the animal's usefulness depends upon hisdelicacy of touch, as, for example, animals used solely for hacking orhunting, his future usefulness in that special sphere of work will be doneaway with. 

Percival himself, always a strong advocate for the operation, fullyrecognises this. 'Does the neurotomized horse maintain the same stepas before?' he asks. 'To this important question, ' he replies, 'Iunhesitatingly answer no; he does not. There can be no doubt but that thehorse _feels_ the ground upon which he is treading, and that he regulateshis action in consonance with such feeling, so as to render his step theleast jarring and fatiguing to himself, and therefore the easiest andpleasantest to his rider. .. . Such impressions'--those of touch--'beingin the neurotomized subject, so far as regards the feeling of the foot, altogether wanting, a bold, fearless projection of the limb in action willbe the consequence, followed by a putting down of the hoof flat upon theground, as though it were a block, creating a sensation alike unpleasantboth to horse and rider. '

Emphatic as Percival is upon this point, there are, nevertheless, otherswho maintain with equal stoutness that the unnerved animal is positively assafe, if not safer, than the animal who has not been so treated. 

'That the tactile sense in the horse's foot is useful, it would be idle todeny; but that it is absolutely essential, even to safe progression, no onewho has paid attention to the results of plantar neurectomy will maintain. On several occasions for years I have hunted, hacked, and driven horseswhich have been deprived of sensation in their fore-feet, and never had anaccident with them. Their action has not been impaired by the operation; onthe contrary, it has been vastly improved compared with what it had beenprevious to it. And my opinion has not been single in this respect, as manycompetent horsemen can give like evidence after long and severe trials ofneurotomized horses. The opponents of neurotomy were, probably, not awarethat there is in progression a _muscular_ as well as a _tactile sense_. '

This latter contention is supported by numerous cases, reported at the timewhen the operation of neurectomy was at the heyday of its popularity. Two Iselect from writings of a later period:

_Recorded Cases_. --1. 'Two of the finest among the many fine horses in theSecond Life Guards were so lame from navicular disease, when I joined theregiment, that they were unsafe and unsightly to ride, and were thereforeentered on the list to be cast off and sold. One was so crippled that itcould scarcely be moved out of its stable. Peeling sorry at having to getrid of such good horses, and anxious to give another blow to the mistakentheory that unnerved animals were unsafe, I obtained the consent of mycommanding officer, who patronizes practical conclusions, to performneurotomy. This was carried out on both horses about eighteen months ago. Within a fortnight they were at their duty, absolutely free from lameness, and with first-rate action, and one of them, from being troublesome andunsteady in the ranks--probably from the pain in its feet--had become quitesteady and tractable. Instead of being lame, blundering, and unsafe, bothwere sound, free in movement, and secure, and, the pain being abolished, they looked improved in condition. 

'During the month of July the regiment attended the summer drills atAldershot, and five days every week for a month these horses carried aweight of about 22 stones each over the roughest and most dangerous ground, nearly always at a fast pace, and for four, five, or six hours each day;and yet they never fell or blundered, and the troopers who rode them hadunbounded confidence in their sure-footedness. They returned to Windsor, atthe end of the month's severe test, as sound in their paces as when theyleft, and certainly now offer no indication whatever that they are lesssafe to ride than any other horse in the regiment. The effects of therelief from pain are also most marked, not only in the altered gait out ofdoors, but also in the stable. '[A]

[Footnote A: _Veterinary Journal, vol_. Ix. , p. 178 (George Fleming, F. B. C. V. S. ). ]

2. 'Some years ago I operated upon a valuable hunter, the property of agentleman in Kildare, the animal having shown unmistakable symptomsof navicular disease for some months previously, and which had beenunsuccessfully combated by the milder forms of treatment for the diseasewithout any benefit. Although the horse went sound, the owner feared toride him, and sent him to be sold in Dublin, where he was disposed of for asmall price, and I then lost sight of him. The following PunchestownRaces, to my surprise, amongst a group of horses walking round the paddockprevious to saddling for an important race, I recognised my old patient, bandaged, clothed, and trained, ready to take his part in the cross-countrycontest, and surrounded by a host of admirers willing to back him at anyprice. 

'Having satisfied myself that it was no other than the same animal, myfirst impulse was at once to find out the jockey who was to ride him, andwarn him of his danger by telling him his mount was devoid of feelingin both fore-feet; but the saddling-bell had already rung, and in a fewmoments more the jockey emerged from the weighing-room and the next view ofthe horse was his tearing up the course in the preliminary, and "pullingdouble. " I was sorry for the jockey if he felt as I did at that moment, forif he did I fear he and his horse would have parted company at the firstfence, as I was certain there would be a smash before the end of the longand difficult three miles of the Kildare Hunt Cup course. It was not untilI saw him again in the front rank passing the stand, in the first round, that I breathed freely, and even then I felt very guilty, and, had he cometo grief badly, I don't think I should ever have operated on another horseexcept in such a way as would have left unmistakable traces after it. 

'"The old horse wins!" screamed a thousand voices as the competitors safelycleared the last bank (now taken away for a gorse fence) the last timeround, and from that moment the operation went up in my estimation ahundredfold, and I almost lost all interest in the finish (and it was aclose one, with my patient a good third), resolving I would operate for thefuture on every animal, young and old, which showed symptoms of naviculardisease. 

'Neither owner nor jockey knew the horse had been operated on, and he wassoon after, on the strength of his performance, sold for a good price tocome to England. It is idle to think that all cases are as successful asthis was, as experience soon told me; but I consider that, in carefulhands, the advantages well outweigh the disadvantages of the operation, andI have selected this instance merely as a practical example. '[A]

[Footnote A: _Veterinary Journal_, vol. Iii. , p. 254 (W. Pallin, M. B. C. V. S. ). ]

It is solely with the object of ventilating both sides of the questionthat we quote the last two cases. In our opinion, the colours in whichthe results of the operation are there painted are far too rosy. Thepractitioner who has before him the task of satisfying a client as to whatwill or what will not be the results of an operation he has suggested willdo well to weigh each side of the argument carefully, and endeavour in hisexplanation to strike the happy mean. 

We hold, further, that the animal who has previously been accustomed tofast work, and to work entailing a large call upon the sense of touch whenpassing over rough and uneven ground, will be far more likely, in hisneurectomized condition, to give satisfaction to his owner if put to aslower and a more suitable means of earning his living. 

CHAPTER VI

FAULTY CONFORMATION

Under this heading we shall deal with such formations of the feet as departsufficiently from the normal to render them serious. Faulty conformationmay be either congenital or acquired, and acquired gradually as the resultof slowly operating causes, or suddenly as the sequel to previous acutedisease. Whether congenital or acquired, serious in its nature orcomparatively of no account, the veterinary surgeon will often find thatthe matter of conformation is one which will have a direct bearing on manyof his 'foot' cases, and, furthermore, that it is one upon which he willoften be called to give advice. 

A. WEAK HEELS. 

_Definition_. --That condition of the wall in which, owing to the softnessof the horn and the oblique direction of the horn fibres, the heels areunable properly to bear the body-weight, and, as a consequence, curve inbeneath the sole. We give the condition first mention, not because of itsgreater importance, but for the reason that it is frequently the forerunnerof the condition to be next described--namely, contracted feet. 

_Symptoms_. --The extreme point of the heel is not affected unless the foothas been greatly neglected, and the condition allowed to develop. Where, however, the foot has been uncared for, curving in of the wall takes placeto an alarming degree, and the heels curl underneath the foot to such anextent as to grow over the sole and the bars. By the pressure they exert onthe sole corns result, and the animal is lamed. 

_Causes_. --In the main this defect is hereditary. It is seen commonly inconnection with flat-foot, and where the horn of the wall is thin andshelly. 

_Treatment_. --In the case of weak or 'turned in' heels no suitable bearingis offered for the shoe in the posterior half of the foot. Any attempt toinduce the heels to bear weight is immediately followed by their bendingin. It follows from this that the best shoe to be used here is one in whichthe bearing is confined to the anterior half of the wall, the heels beingrelieved by being sufficiently pared. As might be expected, this bearing onthe anterior half only of the foot is insufficient; pressure must be giventhe frog. This latter end is best gained by a bar shoe (Fig. 68). With itthe anterior portions of the wall, the whole of the bars, and the wholeof the frog may be in contact, and the heels only so pared as to take nobearing at all. A few such shoeings sees the defect remedied. In everyinstance paring of the sole should be discouraged, as it serves but toincrease the deformity. 

B. CONTRACTED FOOT. 

_(a)_ GENERAL CONTRACTION--CONTRACTED HEELS. 

_Definition_. By the term contracted foot, otherwise known as hoof-bound, is indicated a condition in which the foot, more especially the posteriorhalf of it, is, or becomes, narrower from side to side than is normal. 

It must be borne in mind, however, that certain breeds of horses havenormally a foot which nearer approaches the oval than the circular in form, and that a narrow foot is not necessarily a contracted foot. 

The contraction may be bilateral when affecting both heels of the same footand extending to the quarters, or unilateral when the inside or outsideheel only is affected. 

In some cases contraction is confined to one foot, while in others it maybe noticed equally bad in both. It is a matter of common knowledge thatcontraction is usually seen in the fore-feet, while the hind seldom ornever suffer from it, a fact which, to our minds, seems difficult ofadequate explanation. Zundel explains this by stating that contraction isprincipally _observed_ in the fore-feet, by reason of the fact that whenlameness arises from it alteration in action will more readily be detectedin front than behind. Percival, on the other hand, suggests that thegreater expansive powers of the hind-foot, by reason of the impetus of itsaction, is able to overcome any influence operating towards contraction. Itmay be, however, that given a cause for contraction, such as the removal ofthe frog's counter-pressure with the ground by faulty shoeing or excessiveparing, the fore-feet, by reason of their being called upon to bear thegreater part of the body-weight, are the first to suffer. 

Flat feet with weak heels are those most frequently affected, and, as wehave already intimated, the condition may exist with or without otherdisease of the foot. 

Depending upon its degree, contracted foot may vary from a simpleabnormality, non-inflammatory and painless, to a condition in which itbecomes a veritable disease, giving rise to a bad form of lameness, andbringing about a withered and sometimes discharging and cankerous affectionof the frog. 

_Symptoms_. --In its early stages contraction is difficult of detection, andwhere both feet are affected may for some time go unsuspected. With onlyone foot undergoing change, the early stages may the more readily bemarked, for in this case comparison with the other and sound foot will atonce reveal the alteration in shape. If lameness in the suspected foot ispresent, then any lingering doubt will be quickly dispelled. 

When far advanced, contraction offers signs that cannot well be missed. Theconverging of the heels narrows the V-shaped indentation in the sole forthe reception of the frog. As a consequence of this, the frog itselfbecomes atrophied by reason of the _continual_ pressure exerted upon it bythe ingrowing horn of the wall and the bars. The median and lateral lacunæof this organ, from being fairly broad and open channels, become pressedinto mere crack-like openings (see the commencing of this condition in Fig. 80, and a badly wasted frog in Fig. 74A). As the case goes on, the lateralbranches of the frog entirely disappear, and all that is left of the organis a remnant of its body or cushion, now wedged in tightly between thebars. Following upon the disappearance of the frog, we find that the barsare in contact, or, in some cases, actually overlapping each other at theirposterior extremities. 

At this stage, perhaps, the whole condition has become aggravated by a fouldischarge from the place originally occupied by the frog, and the foot, especially in the region of the heels, has become hot and tender--really aform of local and subacute laminitis. 

The long-continued inflammation, although only of a low type, renders thehorn of the hoof hard and dry, and only with difficulty will the ordinaryfoot instruments cut it. This in its turn leads to cracks and fissures invarious places, but more especially in the bars and what is left of thefrog. Often, too, cracks will appear in the horn of the quarters, and atroublesome and incurable form of sand-crack results. 

An animal with contraction advanced as far as this, especially if confinedto one foot, goes unmistakably lame. With both feet affected, he ordinarilystarts out from the stable in a manner that is commonly called 'groggy. ' Inother words, the gait is uncertain, and feeling; and stumbling is frequent. Anyone who has had the misfortune to drive an animal with feet in thiscondition knows full well that every little irregularity in the road atonce makes itself felt to the feet, and that the animal, as time goes on, learns to carefully avoid any suspicious-looking group of stones he maysee. To drive an animal like this is to keep one's self continually ontenter-hooks, for, sooner or later, the inevitable happens, and the animalcomes down. 

Up to now we have described the changes of form in the hoof as seen whenthe contracted foot is viewed from the solar surface. With those changes asevident as we have depicted them, there will be no difficulty in detectingthe alterations in the form of the wall. 

In addition to a narrowing from side to side there will be noticed anabnormal straightness of the quarters, with a turning in, more or lesssudden, of the heels. This effect is given in these cases by the smithmaintaining the shoe of a length and width that should normally fit a footof that particular animal's size and substance. This is probably done withthe idea of deceiving anyone examining the solar surface. Viewed from thisposition, the width of the shoe at the heels gives the impression that itis attached to a foot of normal breadth. This deception is heightened ifat the same time has been practised the process of 'opening up the heels. 'That expression indicates that the bars have been removed, and the laterallacunæ of the frog made to continue the concavity of the sole. The arch ofthe latter is thus made to appear of much greater extent than it really is, and the heels, by reason of their being abruptly cut off when removing thebars, also convey the false impression of being wide apart. 

The practitioner unversed in the tricks of the forge will best guardagainst this by viewing the foot, while on the ground, from behind. Fromthat position he will be able to detect the lowness of the quarters, andthe projecting portion of the shoe, that the hoof, by reason of its suddenbending inwards, does not touch. 

The 'feeling' manner of the gait before alluded to, together with thedisinclination to put the foot firmly and squarely forward, will sometimeslead the examiner to over-look the contraction, and diagnose his case asone of shoulder lameness. In many cases, too, such consequent conditionsas 'thrushy frogs' and 'suppurating corns' are often treated with utterdisregard of the contraction that has really brought them about. But aboveall, the disease most likely to be confounded with simple contraction isnavicular disease. More than probable it is that many cases of so-called'navicular' have in reality been nothing more than contraction broughtabout by one or other of the causes we shall afterwards enumerate--caseswhere a due attention to the prime cause of the mischief would, in alllikelihood, have remedied the lameness. 

_Changes in the Internal Structures_. --It follows as a matter of coursethat the changes we have described in the form of the hoof itself carrywith them alterations in the bones and sensitive structures beneath it. Thetissues, as a whole, become atrophied. The os pedis becomes deformed, losesits circular shape, and gradually becomes more or less oval in contour. At the same time, its structure becomes more compact, the cribriformappearance of its anterior and lateral faces more or less destroyed, andthe few remaining openings apparently increased in size. This atrophy ofthe os pedis is best noted at the wings. 

In the plantar cushion the effects of the atrophy are noted in thesmallness of the organ, in its becoming whiter in colour than normal, andmore resistant to pressure. 

The coronary cushion is also affected in the same way, where the changesare noted most in its posterior portions. 

A further effect of the narrowing of the heels, and their consequenttendency to drop downwards, is the exertion of a continual pressure on thesensitive sole. In course of time, and especially in flat feet, this leadsto the appearance of corns. 

The navicular bone and bursa and the tendon of the perforans also sufferfrom the effects of compression. The movement of the tendon is restricted, and arterial supply to the adjacent structures rendered deficient. Thetissues of the bone and bursa are insufficiently nourished, and thesecretion of synovia lessened. In this way it is conceivable that naviculardisease may follow the condition of simple contracted heels. 

In common with the other structures, the lateral cartilages also sufferfrom the continual pressure. Their blood-supply is lessened, theirfunctions interfered with, and side-bones result. 

_Causes_. --Upon the causation of contraction a very great deal has beenwritten, both by early veterinarians and by those of the present day. Manyand widely differing opinions have been advanced, but a careful résumé ofonly a few will lead one to certain fixed conclusions. 

We may consider the causes of contraction under two headings--predisposingand exciting. 

_Predisposing Causes of Contraction_. --Among these we will first mentionheredity, although it is possible it should not be deemed of so greataccount as it is by some. That the shape of certain feet, especially thosewith low heels and abnormally sloping walls, predisposes to contraction noone will deny. So long, however, as the animal goes unshod, so long doesthe foot maintain a normal condition of the heels. In other words, itis not until the tendency to contraction already there is aggravated bycareless shoeing and the effects of work that it operates to any noticeableextent. 

The degree of contraction will also be very largely governed by the amountof the development of the frog. With a frog of good size, low down, andtaking part in the pressure of the foot on the ground, contraction willbe prevented. On the other hand, an ill-developed frog, one wasted bylong-continued and spreading thrush, or one robbed of its normal functionby excessive paring in the forge, is a common starting-point of thecondition we are considering. We have already referred to this in ChapterIII. , when considering the experiments of Lungwitz in this connection. Whatwe have to bear in mind in these experiments is that the application ofa pad to the frog, in such a manner that effective ground-pressure isobtained, results always in a marked expansion of the heels, and that, withcounter-pressure with the ground absent, expansion occurs to little orno extent. This is proof positive of the enormous part the frog plays inmaintaining an open and elastic condition of the heels--a fact so insistedon by Coleman. 

It is worthy of mention, however, that loss of the frog's function does notoperate to nearly so serious an extent in horses with high, upright heelsas in those with the heels low and excessively sloping. 

In illustrating this, Mr. Dollar, in his work on shoeing, mentions the caseof a pair of trotting horses of similar age, size, and weight, each havingweak fore-heels. In one case the hoofs were flat, in the other upright. Thehorse with the flat hoofs suffered from contraction, while the other didnot. 

The reason appears to be that in the animal with upright hoofs theproportion of body-weight borne by the heels is considerably less than inthose with the hoofs flat and sloping. 

Certain conditions of the horn-producing membranes also predispose tocontraction. For example, in horses reared on marshy soils, and afterwardstransferred to standing in town stables, we find that a dry and brittlecondition of the horn supervenes. This we may regard as a low form oflaminitis, brought about by the heat of the material upon which the animalis standing, and the congestion of the feet engendered by his enforcedstanding for long periods in one position, as opposed to the more or lesscontinuous exercise when at pasture. With the hoof in this condition itloses by evaporation the moisture that normally it should contain, and, aswe might expect, a certain degree of contraction of its structure is theinevitable result. 

We thus see that contraction brought about in this way is not so muchcaused by the heat of the stable, as it is by the decreased ability of thehorn to retain its own moisture. 

On the other hand, it cannot be denied that excessive warmth and drynesscombined tend also to an undue abstraction of moisture, even from the hornof the healthy foot; and this explains in great measure how it is thatlameness, as a rule, and especially that proceeding from contracted heels, is far more frequent and of greater intensity in the hot, dry months ofsummer, than in the cooler and more humid atmosphere of winter. It isinteresting to note, too, that an alternation of humidity and drynessis far more liable to injure the quality of the horn and tend to itscontraction than the long-continued effects of dryness alone. A commonillustration of this is to be found in the effects of the ordinarypoultice. Everyone knows that when, after a few days' application, they arediscontinued, we get as a result an abnormally dry and brittle state ofthe horn. This is doubtless due to the poultice removing the thin, varnish-like, and protective pellicle known as the periople, and therebyallowing the process of evaporation to act on the water normally containedin the hoof. 

_Exciting Causes of Contraction_. --Among these, first place mustundoubtedly be given to shoeing. This does not necessarily imply shoeingmore than ordinarily faulty, nor a faulty preparation of the foot, butshoeing as it is generally practised. No ordinary shoe, except a fewdevised for the purpose, such as the Charlier or the tip, allows the frogto come in contact with the ground. This we take to be the main factor inthe causation of contracted heels, especially with a predisposition alreadypresent in the foot itself. In the words of Lungwitz: 'Regarded from thispoint of view, there is no greater evil than shoeing. It abolishes thenecessary counter-pressure, and thus interferes with expansion. Bars, sole, and frog cannot perform the functions that naturally belong to them as theywould do without the shoe. '

In addition to the evil of the shoe itself, errors of practice in the forgecontribute to the causation of contraction. Taking first the preparation ofthe foot, we find that often the heels are lowered far too much, and thetoe allowed to remain too long. This can have but one effect--that ofthrowing a greater proportion of the animal's weight upon the heels thanproperly they should bear, with, what we now know to be the consequence ofthat, a corresponding pushing inwards and downwards of the horn; in otherwords, contraction. 

Excessive paring of the bars, to which we have already partly alluded, isalso an active agent in bringing about an inward growth of the horn of theheels and quarters. The bar, or inflexion of the wall at the heel, by meansof its close contact with the frog, communicates the outward movementsof that organ to the wall of the hoof. With the bar removed, the outwardmovements of the frog under pressure are naturally rendered of no account, and a proper and intermittent expansion of the wall denied it. The sameevil follows, though to a less extent, excessive paring of the sole. 

The shape of the bearing surface of the shoe is often to be blamed. Wherethis is concave--'seated'--and the 'seating' is carried back to theheels, it is easy to see that, when weight is on the foot, there is anever-present tendency for the bearing edge of the wall to slide downtowards the inner edge of the shoe. This tendency, operating on both theinner and outer wall simultaneously, must strongly favour contraction. 

A further wrong practice is that of continuing the nailing too far towardsthe heels. In our opinion this is not now often met with. When it occursits effect is, of course, to prevent those movements of expansion of thewall which we now know to be normal and most marked at the heels. 

It may be remarked of the build of the shoe, or of errors in thepreparation of the foot, that neither are of much moment. Neither arethey. But when one stays to consider that errors of this description arepractised not only once, but each time the horse goes to the forge, andthat with some of them--those relating to the build of the shoe--the injurythereby brought about is inflicted not only once, but every day thatparticular shoe is worn, then it is not to be wondered at that, sooner orlater, ill consequences more or less grave result. 

_Prognosis_. --This will depend to a very large extent upon the conformationof the limb, and upon the previous duration of the contraction. Contractionof long standing, where atrophy of the sub-lying, soft structures and thepedal bone may be expected, will prove obstinate to treatment. Especiallywill this be so if the lateral cartilages have become ossified. Neither maywe look for much benefit from treatment if the contraction has occurred inanimals with an oblique foot axis and flat hoofs. 

On the other hand, if the case is comparatively recent, if the limbis straight and the form of the hoof is upright, and if matters areuncomplicated by side-bones, or other serious alteration in the internalstructures, then treatment may be rewarded with some measure of success. 

[Illustration: FIG. 63. --TIP SHOE. The dotted portions represent the lengthof the branches removed. ]

_Treatment_. --The greater part of the treatment of contracted foot willalmost suggest itself as a corollary of the causes we have enumerated. Thenormal width of the heels may be renewed, and development of the wastedfrog brought about by one of three methods:

1. By restoring the pressure from below to the frog. 

2. By the use of an expansion shoe. 

3. By operative measures upon the horn of the wall. 

1. _By Restoring the Pressure from Below to the Frog_. 

This may be accomplished as follows:

_(a) By Shoeing with Tips_. --This method is advocated by Percival, by A. A. Holcombe, D. V. S. , Inspector. Bureau of Animal Industry, U. S. A. , by Dollarin his work on horseshoeing, and by many others. 

Though requiring more care than in fitting the ordinary shoe, theapplication of a tip is simple. In reality, the tip is just an ordinaryshoe shortened by truncating the heels. 

Before applying the tip, the horn of the wall at the toe should beshortened sufficiently to prevent any undue obliquity of the hoof, and thefoot should be so prepared as to allow the heels of the tip to sink flushwith the bearing edge of the wall behind it. 

When the foot does not allow of the removal of much horn at the toe, whatis termed a 'thinned' tip is to be preferred. Its shape is sufficientlyshown by the accompanying figure (Fig. 65). 

With the tip the posterior half of the foot is allowed to come into contactwith the ground, and the object we are striving for--namely, frog pressure, and greater facilities for alternate expansion and contraction of theheels--is thus brought about. 

[Illustration: FIG. 64. --THE TIP SHOE 'LET IN THE FOOT. ]

[Illustration: FIG. 65. --THE THINNED TIP. ]

_(b) By Shoeing with the Charlier_. --The results brought about by the useof a tip may be arrived at by the application of a Charlier or preplantarshoe, or by a modified Charlier or Charlier tip. 

Briefly described, a Charlier is a shoe that allows the sole and the frogto come to the ground exactly as in the unshod foot. This is accomplishedby running a groove round the inferior edge of the hoof by removinga portion of the bearing edge of the wall with a specially deviseddrawing-knife. Into this groove is fitted a narrow and somewhat deep shoe, made, preferably, of a mixture of iron and steel, and forged in such amanner that its front or outer surface follows the outer slope of the wall. 

The Charlier should have the inner edge of its upper surface very slightlybevelled, in order to prevent any pressure on the sensitive sole, andshould be provided with from four to six nail-holes. These latter should besmall in size and conical in shape. The nails themselves should be small, and have a conical head and neck, to fit into the nail-hole of the shoe. 

[Illustration: FIG. 66. --THE SPECIAL DRAWING-KNIFE (FLEMING'S) FORPREPARING THE FOOT FOR THE CHARLIER SHOE. ]

The modified Charlier, or Charlier tip, perhaps the better of the two forthe purpose we are describing, is really a shortened Charlier, and bearsthe same relation to the Charlier proper as the tip does to the ordinaryshoe. It is let into the solar surface of the foot in exactly the samemanner as its larger fellow, but it does not extend backwards beyond thecommencement of the quarters. By its use greater opportunity for expansionis given to the heels than is done by the Charlier with heels of fulllength. 

[Illustration: FIG. 67. --FOOT PREPARED FOR THE CHARLIER SHOE. ]

We do not here intend to deal at any length with the arguments for andagainst the Charlier as regards its adoption for general use. These will befound fully set out in any good work on shoeing. 

The point that it is correct in theory it would be idle to attempt toevade; but that it is generally practicable, or that it offers any verypronounced advantages, as compared with the disadvantages urged against it, over the shoes in ordinary use, the limited favour it has drawn to itself, since its introduction in 1865, seems sufficiently to deny. 

_(c) By the Use of a Bar Shoe_. --Where the frog is not excessively wastedbenefit will be derived from the use of a bar shoe. 

[Illustration: FIG. 68. --BAR SHOE. ]

The transverse portion at the back, termed the 'bar, ' and which givesthe shoe its name, is instrumental in bringing about from below thatcounter-pressure on the frog that we now know to be so necessary a factorin remedying contraction. When the frog, by wasting or disease, isso deficient as to be unable to reach the 'bar, ' this shoe must besupplemented by a leather or rubber sole. 

In the event of corn or sand-crack existing with the contraction, the shoeknown as a 'three-quarter bar' is preferable (see Fig. 103). The break heremade in the contour of the shoe allows of dressing the corn, and, in thecase of sand-crack, removes the bearing from that portion of the wall. _(d) By the Use of a Bar Pad and a Heelless or 'Half' Shoe_. --The barpad consists of a shape of rubber composition firmly fixed to a leatherfoundation, which shape of rubber takes the place of the 'bar' of the barshoe. 

[Illustration: FIG. 69. --RUBBER BAR PAD ON LEATHER. ]

[Illustration: FIG. 70. --THE BAR, PAD APPLIED WITH A HALF-SHOE. ]

For habitual use in such cases as prove obstinate to treatment, or wherea complete cure was never from the commencement expected, the bar pad isundoubtedly one of the most useful inventions to our hand. The animal's'going' is improved, the tender frog is protected from injury by loosestones, and greater comfort given to both the horse and the driver. 

[Illustration: FIG. 71. --FROG PAD. ]

[Illustration: FIG. 72. --FROG PAD APPLIED. ]

_(e) By the Use of a Frog Pad and a Shoe of Ordinary Shape_. --The shape ofrubber on this pad is designed to cover the frog only. Its shape and modeof application is sufficiently shown in the accompanying illustrations. 

_(f) By turning out to Grass_. --Where the expense of keep is no object, areturn of contracted feet to the normal may be brought about by removingthe shoes and turning the animal out to pasture, thus giving the feet theadvantages to be derived from a more or less continuous operation of thenormal movements of expansion and contraction. In this case the treatmentmust extend from three to four, or possibly six months. 

2. _By the Use of Some Form of Expansion Shoe_. 

[Illustration: FIG. 73. --SMITH'S EXPANSION SHOE SEEN FROM ITS GROUNDSURFACE AND FROM THE SIDE. _a_, The screw, with a fine-cut thread; _b_, nutwhich travels along it; _c_, a hollow thimble into which the screw passesat one end, the other being cut out V-shaped to catch into a slot (_d_) onthe shoe; _e, e_, the grip[A] for the bars, the length and direction ofwhich depend upon the shape of the foot; _f, f_, the counter-sunk rivetsforming the hinge (_f_'); _g_, the counter-sunk rivet of the expandingpiece. ]

[Footnote A: The inventor of this shoe uses the word 'grip' to denote what, in describing other expansion shoes, we term the 'clip' (H. C. R. ). ]

_(a) Smith's_. --For many years past continental writers have beenpractising this method. So far as we know, however, Lieutenant-Colonel FredSmith was the first English veterinarian to use a shoe of his own devising, and to report on its effects. This shoe we will, therefore, give firstmention. 

The above figure, with its accompanying letterpress, sufficiently explainsthe nature of the shoe. In fitting the shoe, care must be taken to have thehinges (_f, f_) far enough back, or the shoe will have a tendency to springat the heels, and the grips _(e, e)_, which catch on the bars, will havea difficulty in biting. This trouble will be avoided by having the hingesabout 1-1/2 to 2 inches from the heels. 

After the shoe has been firmly nailed to the foot, the travelling nut _b_is driven forward on the screw _a_ so as to cause the grips to just catchon the inside of the bars of the foot. According to the inventor, theamount of pressure to be exerted must be learned by experience, and hesays:

'I screw up very gradually until I see the cleft of the frog just beginningto open. I now trot the horse up, and if he goes sound it is certain thatthe pressure I have exercised will not give rise to trouble. The animal issent to work to assist in the expansion of the foot. On examining the shoenext day, the grip is found to be quite loose, the foot has enlarged, andthe nut is turned once more until the grip on the bars is tightened, thehorse being again trotted to ascertain that no injurious pressure isexerted. 

'Every day or two I repeat this process, making measurements in all casesbefore widening the heels. The increase in width of the foot which resultsis astonishing, 1/4 to 3/8 inch during the first week may be safelypredicted, and in a month to six weeks it is impossible to recognise in thelarge healthy frog and wide heels, the shrivelled-up organ of a short timebefore. '[A]

[Footnote A: _Journal of Comparative Pathology and Therapeutics_, vol. V. , p. 98. ]

It is pointed out by the writer of the above (and his observations, doubtless, apply to the use of all other expansion shoes in which the barsare gripped and forcibly expanded) that the whole secret of success liesin avoiding injurious pressure by exerting too great an expansion at oneoperation. After each manipulation of the expanding apparatus the horseshould trot sound and the frog remain cool. Should the foot become hot, andlameness supervene, then tension should at once be relaxed. 

_Recorded Cases of the Use of the Shoe_. --The inventor of the shoe relatestwo cases of contracted foot treated by these means in which the heelsof one, after thirty-nine days' treatment, had increased in width to theextent of 1 inch, and the heels of the other, after twenty-four days', hadenlarged 5/8 inch. Of the first case he gives the drawings in Fig. 74. 

A represents the foot before treatment; B the same foot after nine days'treatment, when the heels had widened 3/4 inch; and C the same foot atthe end of the thirty-nine days' treatment, at which date the frog was anexcellent-looking one, and the foot had increased an inch in width. [A]

[Footnote A: _Journal of Comparative Pathology and Therapeutics_, vol. V. , p. 100]

[Illustration: FIG. 74. --THE CHANGES IN FORM OF A CONTRACTED FOOT TREATEDWITH SMITH'S EXPANSION SHOE]

In 1893, at a meeting of the Midland Counties Veterinary MedicalAssociation, the late Mr. Olver said he had applied this shoe to a valuablehunter that had gone so lame that he could scarcely put his foot to theground. After a fortnight's application, and by the assistance of thedouble screw in the shoe, the heel was forced out. Then the horse was putto work with the shoe on, and he had hunted the whole of the last season ina perfectly sound condition. [A]

[Footnote A: _Veterinary Record_, vol. Vi. , p. 143]

F. D. McLaren, M. R. C. V. S. , writes:[A] 'I resolved to try one of CaptainSmith's shoes in a case where the hoof was badly contracted, and where thefrog had entirely disappeared, there being also slight lameness. The roofrapidly expanded, and every other day the nut was moved on a bit to keepthe cross-piece tight. I then had the cross-piece bent downwards a little_to prevent the nut pressing on the rapidly-growing frog_. [B] After anotherfortnight or so, I had a shoe made with clips resting against the inside ofthe bars, [C] and the next time he was shod these were also dispensed with. It is now a year ago since the animal recovered his frog, and he still hasthe largest frog in the stable, and the hoof shows no sign of contraction. '

[Footnote A: _Ibid_. , vol. Vi. , p. 183]

[Footnote B: The italics are mine (H. C. R. ). ]

[Footnote C: The expanding shoe itself was here evidently dispensed with, and an ordinary shoe with bar-clips used in its stead (H. C. R. ). ]

_(b) De Fay's_. --Among other shoes of the expansion class may be mentionedthat of De Fay. Like the preceding, it is a shoe with a flat bearingsurface, and provided with bar-clips. It is, however, _un_ hinged. Therequisite degree of periodic expansion is in this case arrived at by aforcible widening of the heels of the shoe, accomplished by bendingthe substance of which it is made, and for this purpose the instrumentillustrated in Fig. 75 is employed. 

The foot is first properly trimmed by levelling the heels and thinningthe sole on each side of the frog. The shoe is then fixed by nails in theordinary manner, taking care that the last nails come not too far back, andthat the clips rest evenly and firmly on the inside of the bars. 

The dilator, hoof-spreader, or vice, as it is variously called, is thenapplied, its two jaws (_a_ and _b_) fitting against the inner edge ofthe shoe at the heels. Careful note is taken of the width of the hoof asmeasured on the graduated scale (_e_, _e_), and the double screw (_g_, _h_)revolved by means of the wrench (k), until the opening of the jaws thusobtained registers an expansion of 1/12 to 1/8 inch. 

The dilatation is repeated at intervals of from eight to ten days, until, at the expiration of a month or six weeks, the amount of total expansion ofthe heels registers nearly an inch. That the method requires the greatestcare may be gathered from the reports of continental writers. They statethat frequently the pain and consequent lameness keep the patient confinedto the stable for several days. 

Numerous and but slightly differing forms of the dilator are on the market. As in principle they are all essentially the same, and are to be foundillustrated in any reliable instrument catalogue, they need no descriptionhere. 

[Illustration: FIG. 75. --DE FAY'S VICE. ]

_(c) Hartmann's_. --A further useful expansion shoe is that of Hartmann's(Fig. 76), in that it may be adapted for either unilateral or bilateralcontraction. This shoe is also provided with bar-clips, and forciblyexpanded at the heels by means of a dilator. The expansion is governed bysaw-cuts through the inner margin of the shoe directed towards its outermargin, and running only partially through the inner half of the web (seeFig. 76). 

According as the contraction is confined to the inner or outer heel, thesaw-cuts, one or two in number, are placed to the inner or outer side ofthe toe-clip. When the contraction is bilateral, the saw-cuts, one or morein number, are placed on each side of the toe-clip. 

_(d) Broué's_. --This is one of the forms of so-called 'slipper' shoes (seeFig. 77). We have already indicated that the shape of the bearing surfaceof the ordinary shoe--by its 'seating' or sloping from outside toinside--is sometimes a cause of contraction. In the 'slipper' of Brouéthis bearing is reversed, and the slope is from inside to outside. Inthe original form of this shoe the slope to the outside was continuedcompletely round the shoe. Experience taught that the strain this enforcedupon the junction of the wall with the sole was injurious, and that the'reversed seating, ' if we may so term it, was best confined to the hinderportions of the shoe's branches. 

[Illustration: FIG. 76. This figure illustrates the principle of theHartmann expanding shoe. _a, a_, The clips to catch the inside of the bars;_b, c_, saw-cuts. ]

The amount of slope should not be excessive. If it is, too rapid and tooforcible an expansion takes place, and pain and severe lameness results. Dollar gives the requisite degree of incline by saying that the outermargin of the bearing surface of the shoe should be from 1/12 to 1/8 inchlower than the inner. 

In the case of the Broué slipper, it is the animal's own weight that bringsabout the widening of the heels, the slope or outward incline of theslipper simply causing the inferior edge of the wall at the heels to spreaditself outwards instead of sliding inwards on the bearing surface of theshoe. 

[Illustration: FIG. 77. --THE SLIPPER SHOE OF BROUÉ. ]

_(e) Einsiedel's_. --Like the 'slipper' of Broué, the Einsiedel shoe dependsfor its effects upon the slope of the bearing surface. 

It differs from the Broué in being provided with a 'bar-clip. ' This, inaddition to gripping the bars like the bar-clips of other expandingshoes, also assists, under the body-weight, in expanding the heels by thepronounced slope given to its upper surface. The expanding force exertedby the body-weight falls thus, through the medium of the bar-clip, clip, _partly_ upon the bars, instead of, as in the Broué, solely upon the wall. We say _partly_ advisedly, for, in addition to the slope upon the outerside of the bar-clips, the bearing surface of the heels of the shoe is_slightly_ sloped outwards also. The good office served by the bar-clip isthe lessening of any tendency to strain upon the white line. 

[Illustration: FIG. 78. --THE SLIPPER AND BAR-CLIP SHOE OF EINSIEDEL. ]

Those we have described by no means exhaust the number of expansion shoesthat have been devised. There are numerous others, many of which arecomposed of three-hinged portions, the two hindermost of which aregradually separated by a toothed arrangement of their inner margins anda travelling bar, the disadvantage of which is that it is liable to workloose. In the majority of this class of shoe the hinges are placed farforward, one on each side of the toe. They there become exposed toexcessive wear. In fact, against the bulk of this form of shoe it maybe urged that they cannot be worn by the animal at work, that they areexpensive, difficult to make, and easily put out of order. 

3. _By Operations on the Horn of the Wall_. 

_(a) Thinning the Wall in the Region of the Quarters_. --This is bestdone by means of an ordinary farrier's rasp. The thinning should lessengradually from the heel for 2-1/2 to 3 inches in a forward direction. Thatportion of the wall next to the coronary border, about 1/2 inch in breadth, should not be touched. At this point the thinning should commence, shouldbe at its greatest, and lessen gradually downwards until at the inferiormargin of the wall the normal thickness of horn is left. The animal is thenshod with a bar shoe and the hoof bound with a bandage soaked in a mixtureof tar and grease, in order to keep the thinned portion of the wall fromcracking. In this condition the animal may remain at light labour. 

When possible, however, it is better to combine the thinning process thusdescribed with turning out to grass. In this case the ordinary shoe isfirst removed, and the foot poulticed for twenty-four hours to renderthe horn soft. The foot is then prepared by slightly lowering theheels--leaving the frog untouched--and thinning the quarters in exactly themanner described above. 

After this is done, the animal is shod with an ordinary tip, a sharpcantharides blister applied to the coronet, and then turned out in a damppasture. In this case the object of the tip is to throw the weight onto the heels and quarters. The thinned horn yields to the pressure thusapplied, and a hoof with heels of a wider pattern commences to grow downfrom the coronet. Two to three months' rest is necessary before the animalcan again he put to work. [A]

[Footnote A: This is the treatment strongly advocated by A. A. Holcombe, D. V. S. , Inspector, Bureau of Animal Industry, U. S. A. ]

_(b) Thinning the Wall in the Region of the Toe_. --This is done withthe idea that the tendency of the heels to expand under pressure of thebody-weight is helped by the thinned portion at the toe allowing the heelsto more readily open behind. Seeing that in the case of toe sand-crack theconverse is argued--that contraction of the heels readily takes place andforces the sand-crack wider open--it is doubtful whether this method is ofany utility in treating contracted heels. 

_(c) Grooving the Wall Vertically or Horizontally, and Shoeing with a BarShoe_. --Marking the wall with a series of grooves, each running in a moreor less vertical direction, was suggested to English veterinarians bySmith's operation for side-bones. 

The manner of making the grooves, and the instruments necessary, will befound fully described in Section C of Chapter X. 

That the method is followed by satisfactory results the undermentioned casewill show:

'A mare, which I have had in my possession since she was a foal, has alwayshad contracted feet, which were also unnaturally small. .. . Lately the marehas been going very "short, " and at length her action was quite crippled. At times she was decidedly lame on the off fore-foot. At no time have Ibeen able to detect any sign of structural disease. I thereupon concludedthat the lameness was due to mechanical pressure on the sensitivestructures, and I determined to try the effects of the above treatment. Asthis was my first experience of the process, I was careful to carry it outin all its details, as described by Professor Smith. After the bar shoeshad been put on, the mare was very lame. I allowed her two days' rest, thencommenced regular walking exercise, and she daily improved. After fourteendays there was no lameness, but still short action. I thereupon gave themare another week's walking exercise, at the expiration of which I droveher a short turn of five miles, which she did quite well, and free fromlameness. For three months I kept the saw-cuts open to the coronet, andcontinued the bar shoes, keeping the mare at exercise, and giving heroccasionally a drive. She never liked the bar shoes, and I was glad when Icould discontinue them, which I did in the fourth month. When shod with theusual shoes the complete success of the treatment was shown. I have now hadher going with the ordinary shoes for the past two or three months, and theimprovement in the shape of the feet is very marked; there is no lameness;the mare is free in movement, fast, and spirited, whereas previously shewas quite the reverse, and almost unfit to drive. '[A]

[Footnote A: W. S. Adams, M. R. C. V. S. , _Veterinary Journal_, vol. Xxx. , p. 19. ]

This method, though but recently introduced to the English veterinarysurgeon, is by no means new. According to Zundel, it was recently madeknown on the Continent by Weber, but was previously known and mentioned byLagueriniere, Brognier, and Hurtrel d'Arboval. 

When the grooving is in a horizontal direction, a single incision issufficient. This is made 3/4 inch below the coronary margin of the wall, and parallel with it, extending from the point of the heel for 2 or 3inches in a forward direction. As in the previous method, a bar shoe isapplied, and the animal daily exercised. Thus separated from the fixedand contracted portion of the wall below, the more elastic coronet underpressure of the body-weight commences to bulge. The bulging is of suchan extent as to cause the new growing hoof from the top to considerablyoverhang the contracted portion below, and cure of the condition resultsfrom the newly-expanded wall above growing down in a normal direction. 

This consideration of contracted heels may be concluded by drawingattention to the advisability of always maintaining the horn of the wall inas soft and supple a condition as is natural by the application of suitablehoof dressings. 

A useful one for the purpose is that made with lard, to which has beenadded a small quantity of wax or turpentine. 

Especially should a dressing like this be used when the hoof is inclinedto be hard and brittle, and where tendency to contraction has already beennoticed. 

The application of a hoof ointment is also particularly indicated where thefoot is much exposed to dampness, where the animal is compelled to standfor long periods upon a dry bedding, or where the bedding is of a substancecalculated to have a deleterious effect upon the horn. 

This, in conjunction with correct shoeing, will probably serve to avoid thenecessity for more drastic measures at a later time. 

_(b)_ LOCAL OR CORONARY CONTRACTION. 

_Definition_. --Contraction at the heels, confined to the horn immediatelysucceeding that occupied by the coronary cushion. Really, the condition isbut a somewhat arbitrary subdivision of contracted hoof, as we have justdescribed it in general. For that reason we shall give it but very briefmention. 

_Symptoms_. --In this case the horn of the heels, instead of running downin a straight line from the coronary margin to the bearing surface of thewall, presents a more or less distinct concavity (See Fig. 79, _a_, _a_). 

As is the case with contraction considered as a whole, this deformity mayaffect one or both heels; and during its first appearance, which is afterthe first few shoeings, the animal may go distinctly lame. 

_Causes_. --Coronary contraction may occur in hoofs of normal shapeimmediately shoeing is commenced, and frog pressure with the groundremoved. It is far more likely to ensue, however, if the hoof is flat, with the heels low, and the wall sloping. And with those predisposingcircumstances it is that the horse goes lame, and not with the hoof ofnormal shape. 

Seeing, then, that this condition is largely dependent upon the shape ofthe foot, we may, to some extent, regard it as hereditary. Seeing further, however, that it only appears when shoeing is commenced, we may in agreater degree also regard it as acquired. The lesson, therefore, that thisand other forms of contraction should teach us is the carefulness withwhich the shoeing should be superintended in a large stud, or in any casewhere the animal is of more than ordinary value. 

[Illustration: FIG. 79. --HOOF WITH LOCAL OR CORONARY CONTRACTION (ASINDICATED AT THE POINTS _a, a_). ]

The explanation of the restricted nature of this form of contractionis simple enough. We have only to refer to the lessons taught by theexperiments of Lungwitz, described in Chapter III. , and the conditionalmost explains itself. We remember that, briefly, the coronary margin ofthe wall resembles a closed elastic ring, which yields and expands tolocal pressure, no matter how slight. We remember also that removal of thecounter-pressure of the frog with the ground tended to contraction of thewall's solar edge when weight was applied. Connect these two facts withthe experience that this form of contraction more often than not occurs inhoofs with sloping heels, and we arrive at the following:

1. The excessive slope of the heels tends to throw a more than usual partof the body-weight upon the posterior portion of the coronary margin ofthe wall, with a consequent expansion of that part of the coronary marginimplicated. 

2. That the shoeing, in removing the counter-pressure of the frog with theground, is at the same time tending to bring about contraction of the lowerportions of the wall at the heels and quarters. 

3. That this tendency to contraction will at first appear in the thinnerportion of the area of wall named--namely, in that immediately below thebulging coronary margin. 

We thus get the appearance depicted in Fig. 79--a contraction _(a, a)_ ofthe heels in the horn below the coronary margin, with the coronary marginitself bulging above, and a hoof of apparently normal width below. 

We say 'apparently' with a purpose, for, as actual measurements will show, the wall near the solar edge is really contracting, for reasons which wehave just described connected with shoeing. Its 'appearance' of normalwidth is accounted for thus: The contraction at _a, a_ is caused by thedragging inwards of the coronary cushion brought about by the sinkingdownwards of the plantar cushion, with which body it will be remembered thecoronary cushion is continuous. With the constant dragging in and downof the coronary cushion there is given, to the horn-secreting papillæ, studding both the lower third of its outer face and its lowermost surface, a distinct 'cant' outwards. Below the lowermost limit of the coronarycushion, then, by reason of the cant outwards of the coronary papillæin the situations mentioned, the horn of the wall takes a more outwarddirection than normal, a fact which lessens in effect the contraction as awhole really going on. It is interesting, too, to note that by this outwardcant of the wall below, and the bulging of the coronary margin above it, the contraction (_a, a_) is heightened in effect, and caused to appeargreater than really it is. 

From what we have said it follows that contraction of the heels, exceptingthe extreme coronary margin, is existent generally, and not confined solelyto _a, a_. 

We have, then, in this condition, as we indicated at the commencement, but a phase in the evolution of ordinary contracted heels, for, with theprogress of the contraction already existing at _a, a_, and below thosepoints, it is only fair to assume that with it falling in of the at presentbulging coronary margin must sooner or later occur, that, though expandedwhen compared with the wall below it, it will be really contracted ascompared with what it was once in that same foot. 

We may therefore conclude this section by remarking that factors tending tocontraction of the heels in general are equally potent in the causation ofcontracted coronet alone. 

_Treatment_. --Exactly that described for contracted heels. Bearing in mindthat contracted coronary margin is but the onset of contracted heels, andthat its first exciting cause is that of removal of the ground-pressureupon the frog, the most careful attention must be paid to the shoeing. Theuse of bar shoes, ordinary frog pads, or heelless shoes and bar pads, areespecially indicated, together with abundant exercise. By these means thenormal movements of expansion will be brought into play, and the conditionquickly remedied. 

C. FLAT-FOOT. 

_Definition_. --By this term is indicated a condition of the foot where thenatural concavity of the sole is absent. 

_Symptoms_. --In the flat-foot the inferior edge of the wall, the sole, and the frog, all lie more or less in the same plane. It is a conditionobserved far more frequently in fore than in hind limbs, and is seen inconnection with low heels, more or less obliquity of the wall, and atendency to contraction. The action of the animal with flat feet is heavy, a result partly of the build of the foot, and partly of the tenderness thatsoon comes on through the liability of the sole to constant bruising. 

[Illustration: FIG. 80. This figure represents the lower surface of atypical flat-foot. It illustrates, too, the commencement of a condition wereferred to in Section B of this chapter--namely, the compression of thefrog by the ingrowing heels (b) and bars (a). ]

_Causes_. --Flat-foot is undoubtedly a congenital defect, and is seencommonly in horses of a heavy, lymphatic type, and especially in thosebred and reared on low, marshy lands. It is thus a common condition of thefore-feet of the Lincolnshire shire. 

As might be expected, a foot of this description is far more prone tosuffer from the effects of shoeing than is the foot of normal shape, andregarded in this light shoeing may be looked upon as, if not an actualcause, certainly a means of aggravating the condition. Directly theshoe--or at any rate the ordinary shoe--is applied, mischief commences. Thefrog is raised from the ground, and the whole of the weight thrown on tothe wall. The heels, already weak and inclined to turn in, are unable tobear the strain. They _turn in_, and contraction commences. This 'turningin' of the heels is favoured by the undue obliquity of the wall. At thesame time, the sole being archless, a certain amount of elasticity islost. The weight is thrown more on to the heels, and the os pedis slightlydescends, rendering the flatness of the sole even more marked than before. With the loss of elasticity of the sole concussion makes itself more felt. The animal is easily lamed, bruised sole becomes frequent, and corns sooneror later make their appearance. 

_Treatment_. --Flat-foot is incurable. All that can be done is to paycareful attention to the shoeing, and so prevent the condition from beingaggravated. In trimming the foot the sole should not be touched; the frog, too, should be left alone, and the wall pared only so far as regards brokenand jagged pieces. 

The most suitable shoe is one _moderately_ seated. If the seating isexcessive, and bearing allowed only on the wall, there is a tendency forthe wall to be pushed outwards, and for the sole to drop still further. Onthe other hand, if the seating is insufficient, or the web of the shoe toowide, and too great a bearing thus given to the sole, then we get, first, an undue pressure upon the last-named portion of the foot a bruise, and, finally, lameness. The correct bearing should take in the whole of the walland the whole of the white line, and should _just impinge_ upon the sole. Above all, the heels of the shoe should be of full length, otherwise, ifthe shoe is worn just a little too long, its heels are carried under thesole of the foot, and by pressure there produce a corn. 

If, with these precautions in shoeing flat-foot, tenderness still persists, a sole of leather or gutta-percha must be used with the shoe. 

D. PUMICED-FOOT, DROPPED SOLE, OR CONVEX SOLE. 

_Definition_. --This term is applied to the foot when the shape of the soleis comparable to the bottom of a saucer. When least marked it is really anaggravated form of flat-foot. 

_Symptoms_. --In pumiced-foot the sole projects beyond the level of thewall. The obliquity of the latter is more marked than in the previouscondition, and progression, to a large extent, takes place upon the heels. In addition to its deformity, the horn is greatly altered in quality, and, as the name 'pumice' indicates, is more or less porous in appearance, bulging, and brittle. 

_Causes_. --As a general rule, it may be taken that pumiced-foot is a sequelof previous disease, although in its least pronounced form it may occur asthe result of accidental or other causes, such as those described in thecausation of flat-foot. 

Occurring in its most marked form, there is no gainsaying the fact thatpumiced-foot is a sequel of either acute or subacute laminitis. As we shallsee when we come to study that disease, the dropping of the sole is broughtabout by distinct and easily-understood morbid processes affecting thesensitive structures. Briefly, these morbid processes in laminitis may bedescribed thus: The accumulated inflammatory exudate, and in some casespus, weakens and destroys the union between the sensitive and insensitivelaminæ. This separation, for reasons afterwards to be explained, isgreatest in the region of the toe. The os pedis, loosened from its intimateattachment with the horny box, is dropped upon the sole, and the sole, unable to bear the weight, commences to bulge below. 

The altered character of the horn is accounted for by the inflammatorychanges in the sensitive laminæ and the papillæ of the keratogenousmembrane generally, for it follows as a matter of course that thesetissues, themselves in a diseased condition, must naturally produce a hornof a greatly altered and inferior quality. 

When following the _subacute_ form of laminitis, the changes characterizingpumiced-foot are slow in making their appearance. The animal at first goesshort, and the lameness thus indicated gradually becomes more severe, untilthe animal is no longer able to work. The feet become hot and dry, thehoof loses its circular form, and the growth of horn at the heels becomesexcessive. At this stage the appearance of bulging at the sole begins tomake itself seen. Later, the outer surface of the wall becomes 'ringed' or'ribbed, ' the rings being somewhat closely approximated in the region ofthe toe, and the distance between them gradually widening towards theheels. The wall too, especially in the region of the toe, instead ofrunning in a straight line from the coronary margin to the shoe, becomesconcave. It is this change, together with the appearance of the rings, thatindicates the loosening of the attachment of the os pedis to the wall, andits afterwards backward and downward direction (see Fig. 124). 

[Illustration: FIG. 81. --HOOF WITH THE RIBS OR RINGS CAUSED BY CHRONICLAMINITIS. ]

As a sequel of _acute_ laminitis, these changes make their appearance withmore or less suddenness, and are generally complicated in that they owetheir occurrence to the formation of pus within the horny box. 

_Treatment_. --Pumiced-foot is always a serious condition. The animal isuseless for work upon hard roads or town pavings, and is of only limitedutility for slow work upon soft lands. The more serious form, thatfollowing acute laminitis, and complicated by the presence of pus, we mayregard as beyond hope of treatment. 

With the more simple form of the condition, we may do much to rendergreater the animal's usefulness. The same principles as were applied to theshoeing of flat feet will have to be observed here. Trimming or paringof any kind, save 'straightening up' of the wall, must be severelydiscountenanced. A broad-webbed shoe, one that will give a certain amountof cover to the sole, is indicated. As in the treatment of flat-foot, however, direct pressure upon the sole must be avoided, and the shoe'seated. ' The 'seating, ' however, should not commence from the absoluteouter margin of the shoe's upper surface. A _flat_ bearing should be givento the wall and the white line, and the seating commenced at the sole. 

We have already remarked on the increased growth of horn at the heels. Itis in this position, then, that will be found the greatest bearing surfacefor the shoe, and it is wise, in this case, to have the heels of the shoekept flat. In other words, the 'seating' is not to be continued to thehindermost portion of the branches of the shoe. By this means there may beobtained at each heel a good solid bearing of from 2 to 3 inches, whichwould otherwise be lost. 

Where the accompanying condition of the horn is bad enough to indicate it, a leather sole should be used, beneath which has been packed a compress oftow and grease, rendered more or less antiseptic by being mixed with tar. 

Where the sole is exceedingly thin, and inclined to be easily wounded, andwhere the hoof, by its brittleness, has become chipped and ragged at thelower margin of the wall, it may perhaps be more advantageous to use, inplace of the compress of tow, the _huflederkitt_ of Rotten. This is aleather-like, dark brown paste. When warmed in hot water, or by itself, itbecomes soft and plastic, and may readily be pressed to the lower surfaceof the foot, so as to fill in all little cracks and irregularities, andfurnish a complete covering to the sole and frog, and to the bearingsurface of the wall. When cold it hardens, without losing the shape givento it, into a hard, leather-like substance. 

Treated in this way, the animal with pumiced feet may yet be capable ofearning his living at light labour or upon a farm. 

E. 'RINGED' OR 'RIBBED' HOOF. 

_Definition_. --A condition of the hoof in which the wall is marked by aseries of well-defined ridges in the horn, each ridge running parallel withthe coronary margin. They are known commonly as 'grass rings, ' and may beeasily distinguished from the more grave condition we have alluded to asfollowing laminitis, by the mere fact that they do not, as do the laminiticrings, approximate each other in the region of the toe, but that they runround the foot, as we have already said, _parallel with each other_. 

[Illustration: FIG. 82. --HOOF SHOWING THE RINGS IN THE HORN BROUGHT ABOUTBY PHYSIOLOGICAL CAUSES. ]

_Causes_. --This condition is purely a physiological, and not a pathologicalone, and the words of its more common name, 'grass rings, ' sufficientlyindicate one of the most common causes. Anything tending to an alternateincrease and decrease in the secretion of horn from the coronet will bringit about. Thus, in an animal at grass, with, according to the weatherconditions, an alternate moistness and dryness of the pasture, with itsconsequent influence on the horn secretion, these rings nearly alwaysappear. The effects of repeated blisters to the coronet make themselvesapparent in the same way, and testify to the efficacy of blisters in thisregion in any case where an increased growth of horn is deemed necessary. From this it is clear that the condition depends primarily upon theamount and condition of the blood supplied to the coronary cushion. Thus, fluctuations in temperature during a long-continued fever, or the effectsof alternate heat and cold, or of healthy exercise alternated withcomparative idleness, will each rib the foot in much the same manner. 

_Treatment_. --The condition is so simple that we may almost regard itas normal. Consequently, treatment of any kind is superfluous. Whereconstitutional disturbance is exerting an influence upon either the qualityor quantity of the blood directed to the part, then, of course, attentionmust be paid to the disease from which it is arising. 

F. THE HOOF WITH BAD HORN. 

(_a_) THE BRITTLE HOOF. 

_Definition_. --As the name indicates, we have in this condition anabnormally dry state of the horn. 

_Symptoms_. --These are obvious. The horn is hard, and when cut by thefarrier's tools gives the impression of being baked hard and stony, thenatural polish of the external layer is wanting, and there is present, usually, a tendency to contracted heels. With the dryness is a liability tofracture, especially at points where the shoe is attached by the nails. As a consequence, the shoes are easily cast, leading to splits in thedirection of the horn fibres. These run dangerously near the sensitivestructures, giving rise in many cases to lameness. Even where pronouncedlameness is absent the action becomes short and 'groggy, ' and the utmostcare is required in the shoeing to keep the animal at work. 

_Causes_. --To a very great extent the condition is hereditary, and isobserved frequently in animals of the short, 'cobby' type. In poniesbred in the Welsh and New Forest droves the condition is not uncommon, especially in the smaller animals. Animals who have had their feet muchin water--as, for instance, those bred and reared on marshy soils--andafterwards transferred to the constant dryness of stable bedding, are alsoparticularly liable to this condition. It is noticed, too, following theexcessive use of unsuitable hoof-dressings, more especially in cases wherecoat after coat of the dressing is applied without occasionally removingthe previous applications. 

_Treatment_. --As a prophylactic, a good hoof-dressing is indicated. Itshould not consist solely of grease, but should have mixed with it eitherwax, turpentine, or tar. 

Above all, careful shoeing should be insisted on, and the owner of ananimal with feet such as these will be well advised if he is recommended tohave the shoeing superintended by one well competent to direct it rightly. The foot should be trimmed but lightly, always remembering that in a footof this description the horn, in addition to being brittle, is generallyabnormally thin. Jagged or partly broken pieces should be removed, and thebearing surface rendered as level as possible. The foot should be carefullyexamined before punching the nail-holes in the shoe, and the nail-holesafterwards placed so as to come opposite the soundest portions of horn. Thenails themselves should be as thin as is consistent with durability, andshould be driven as high up as possible. 

On the least sign of undue wear the shoes should be removed, never, as istoo often done, allowing them to remain on so long that a portion breaksaway. If, with the laudable idea of not interfering with the horn more thanis possible, this is practised, the portion of the shoe breaking off isbound to tear away with it more or less of the brittle horn to which it isattached. 

Where the breaks in the horn are so large as to prevent a level bearing forthe shoe being obtained, the interstices should be filled up with one orother of the preparations made for this purpose. One of the most suitableis that discovered by M. Defay. By its means sand-cracks or other fracturesof the horn may be durably cemented up. 

'Even pieces of iron may be securely joined together by its means. The onlyprecaution for its successful application is the careful removal of allgrease by spirits of sal-ammoniac, sulphide of carbon, or ether. M. Defaymakes no secret of its composition, which is as follows: Take 1 part ofcoarsely-powdered gum-ammoniac, and 2 parts of gutta-percha, in pieces thesize of a hazel-nut. Put them in a tin-lined vessel over a slow fire, andstir constantly until thoroughly mixed. Before the thick, resinous massgets cold mould it into sticks like sealing-wax. The cement will keepfor years, and when required for use it is only necessary to cut off asufficient quantity, and remelt it immediately before application. We havefrequently used this cement for the repair of seriously broken hoofs. It isso tenacious that it will retain the nails by which the shoe is attachedwithout tearing away from the hoof. '[A]

[Footnote A: _Veterinary Journal_, vol. Iii. , p. 71. ]

Failing this, the bearing surface may be made level, and fractures repairedby using the _huflederkitt_ described in the treatment of pumiced sole. 

(_b_) THE SPONGY HOOF. 

_Definition_. --This is the opposite condition to the one we have justdescribed, and is characterized by the soft and non-resistant qualities ofthe horn. 

_Symptoms_. --Spongy hoof is quite common in animals that have large, flat, and spreading feet--in fact, the two appear to run very much together. Itis a common defect in animals reared in marshy districts, and of a heavy, lymphatic type. The Lincolnshire Shire, for instance, has often feetof this description, and, the causative factors being in this caselong-continued, render the feet extremely predisposed to canker. The hornis distinctly soft to the knife, and has an appearance more or less greasy. Animals with spongy feet are unfit for long journeys on hard roads. Whencompelled to travel thus, the feet become hot and tender, and lamenessresults. A mild form of laminitis, extending over a period of three orfour days, often follows on this enforced travelling on a hard road, moreespecially in cases where the animal is 'heavy topped, ' and the usualfood of a highly stimulating nature. In fact, it has been the author'sexperience to meet with this condition several times in the case of shirestallions doing a long walk daily upon hard roads, with the weather hot anddry. 

_Treatment_. --When a horse with spongy feet is shod for the first time, care must be taken to avoid excessive paring of the sole, for already thenatural wear of the foot has been sufficient to keep the soft horn in astate of thinness. For the same reason hot fitting of the shoe must notbe indulged in for too long a time. That common malpractice of the forge, 'opening up the heels, ' must, in this case, be especially guarded against, or the excessive paring of the frog and partial removal of the bars thatthis operation consists in will lay the foot open to risk of contraction. To begin with, the heels are naturally weak, and, once the bars areremoved, there is nothing to prevent them rapidly caving in towards thefrog. Even when carefully shod, a foot of this class is readily prone tocontract directly the animal is brought into the stable, and the horncommences to dry to excess. An ordinary light shoe should be used, and thenails should be light and thin. They should be driven carefully home, andthe 'clinching' made as tight and secure as possible. 

G. CLUB-FOOT. 

_Definition_. --Under this name we indicate all cases in which the hornof the wall become straightened from above to below. It will, therefore, include all conformations varying from the so-called 'upright hoof, ' inwhich the toe forms an angle of more than 60 degrees with the ground, tothe badly 'clubbed' foot, in which the horn at the toe forms a right anglewith the ground, or is even directed obliquely backwards and downwards, sothat the coronary margin overhangs the solar edge of the wall. 

[Illustration: FIG. 83. --THE CLUB-FOOT. ]

_Symptoms_. --Even in its least pronounced form the condition is apparent ata glance, the alteration in the angle formed by the hoof with the groundstriking the eye at once, and the heels, as compared with the toe, appearing much too high. When the condition is slight, the wall of the toeis about twice as high as that of the heels, while in the most marked formthe toe and the heels may in height be nearly equal (see Fig. 83). Whencongenital, but little interference with the action is noticed. Suchanimals, by reason of their 'stiltiness, ' are unfit for the saddle, but atordinary work will perform their duties equally well with the animal ofnormal-shaped feet. When acquired as the result of overwork, of contractedtendons, or other causes, however, the gait becomes stumbling anduncertain. The body-weight is transferred from the heels to the anteriorparts of the foot, and the shoe shows undue signs of wear at the toe. 

_Causes_. --Upright hoof is undoubtedly hereditary, and is even seen as anatural conformation in the feet of asses and mules. When hereditary in thehorse, however, it is certainly a defect, and is associated commonly withan upright limb, and a short, upright pastern (see Fig. 83). 

Among other causes, we may enumerate sprains or wounds of the flexortendons, or any disease of the limbs for a long time preventing extensionof the fetlock-joint, such as sprains or injuries of the posteriorligaments of the limb, splints or ringbones so placed as to interfere withthe movements of the flexor tendons, or, in the hind-limb, spavin, keepingfor some months the fetlock in a state of flexion. In the very young animalthe condition may be induced by an improper paring of the foot--cuttingaway too much at the toe, and allowing the heels to remain. 

_Treatment_. --When the condition is congenital, no treatment at all isindicated. It might, in fact, be said that interference would tend ratherto minimize than enhance the animal's usefulness; for, in this case, theclub-shaped feet are in all probability due to faulty conformation above. In other words, the upright hoof is in this instance but a natural resultof the animal's build, with which useful interference is impossible. 

Where the upright hoof is a consequence of excessive paring of the toe, or insufficient removal of the heels, the condition may be remedied bydirecting attention to those particulars, and preventing their continuance. At the same time, a greater obliquity of the limb axis may be given by theuse of a suitable shoe. The shoe indicated is a short one, with thin heelsand a thick toe. In some cases the abnormality may be remedied by the useof a tip. Whatever method is adopted, care must be taken not to attempttoo positive a change in the direction of the limb at one operation. Theprocess must be gradual. 

In cases where the abnormality has been brought about by wounds to theflexor tendons, the alteration in the direction of the limb is often sogreat as to produce 'knuckling over' of the fetlock. This, to a very greatextent, may be remedied by the use of a shoe with calkins and an extendedtoe-piece (see Fig. 84). 

[Illustration: FIG. 84. --THE SHOE WITH EXTENDED TOE-PIECE AND HIGHCALKINS. ]

With this shoe a certain amount of forced exercise is advisable, and atintervals of about two weeks the calkins should be somewhat lowered, untilthe heels are brought as close to the ground as is possible. In givingdirections for this shoe to be made the veterinary surgeon must, whenreferring to the length of the toe-piece, be guided entirely by thecondition of the case. Ordinarily, a suitable length is from 3 to 4 inches. It is necessary also to warn the owner that, by reason of the lengthprojecting, the shoe is liable to be torn off. 

Should the 'knuckling over' have become complicated by bony deposits roundthe seat of the original injury, then a favourable modification of thecondition is not so likely to result. 

The benefit to be derived from the shoe with an extended toe-piece in acase of excessive knuckling is admirably shown in a brief report of a case, under the title of 'Hooked Foot, ' in vol. Xiv. Of the _Veterinary Record_, p. 716:

'An eighteen months' old filly showed a deformity of the third phalanx, resulting in her walking with the front face of the hoof on the ground. Theflexors were apparently all right, and the bending back seemed to be due tocontraction of the ligaments of the joint and the sheath of the perforans. 

'On the ground of absence of contraction of the flexors, or atrophy andparalysis of the extensors, the surgeon considered the lesion curable bysimple orthopædic measures. By means of an elongated toe-piece to theshoe and calkins, which were shortened every fifteen days, the filly wascompletely cured in seventy days. '

H. THE CROOKED FOOT. 

(_a_) THE FOOT WITH UNEQUAL SIDES. 

_Definition_. --The foot thus affected has one side of the wall higher thanthe other. 

_Symptoms_. --This deformity is the better recognised when the foot on thefloor is viewed from behind. In addition to the difference between theheight of the inner and outer heel is seen at once a deviation in thenormal direction of the horn. That of the higher side is distinctly moreupright than that of the lower, and runs from above downwards and inwardstowards the axis of the foot, while the horn of the lower side maintainsits normal direction of downwards and outwards. 

From what we have said before on contracted foot, this bending in ofthe wall of the upright side will at once be recognised as a form ofcontraction. It is, in fact, contraction confined to one-half of the footonly, and, as a result, the upright side of the crooked foot is prone tothe troubles arising from that condition. Corns are frequent, and atrophyof that half of the frog on the affected side supervenes. With theinflammatory changes accompanying these conditions we find the horn of theaffected side deteriorating in quality. It becomes dry and brittle, andextremely liable to sand-crack. At the same time, thrush of the contractedfrog begins to make its appearance. 

_Causes_. --More often than not this condition is a result of theconformation of the limb. According as the build above inclines the animalto 'turned in' or 'turned out' toes, so shall we have feet with a wallcrooked inwards or crooked outwards; and it may be mentioned here that theevil results inflicted on the foot by ill-shaped limbs above will makethemselves the more readily noticed when the animal comes to be shod forany length of time. So long as a natural wear of the foot is allowed, so long does it accommodate itself to the form of limb above. So soon, however, as the shoe is applied, and a more or less equal (and in this caseharmful) wear by that means insisted on, so soon does this abnormal changein the height and direction of the horn fibres begin to make itself seen. 

While arising in the majority of instances from faulty conformation of thelimb, crooked feet may also be brought about by bad shoeing, or by unequalparing of the foot, and, in a few cases, from unequal wear of the foot in astate of nature. 

_Treatment_. --Although it may be taken as a rule that lowering of thehigher wall, even if persisted in at every shoeing, will do nothing towardsremedying the primary cause (viz. , the evil conformation of the limb), yetit will serve to keep the condition within reasonable limits. In this case, while removing so much of the wall as is deemed necessary, care must betaken to leave uncut the sole and the bar. Leaving these intact gives ustwo natural and very potent protections against the contraction alreadymentioned as impending. 

Where, by reason of the thinness of the horn or other causes, sufficientparing to equalize the tread cannot be practised, then the same end may bearrived at by the use of special shoes. That branch of the shoe applied tothe half of the foot with the lower wall should be thickened from abovedownwards. Or, on the same branch, may be turned up a calkin of sufficientheight for the purpose. Of the two methods the first is preferable. 

In any case, whether depending upon paring, or upon the use of a specialshoe, the animal should be sent to the forge quite often, for it is only bya well-directed, and therefore constant, application of the principles herelaid down that improvement may be brought about. 

When marked contraction of one-half of the foot is present, it will bebest treated with the expanding shoe of Hartmann, already described in thesection of this chapter dealing with contracted heels (see Fig. 76). 

(_b_) THE CURVED HOOF. 

_Definition_. --The hoof with the wall of one side convex, and that of theopposite side concave. Fig. 85, showing the foot in section from side toside, gives an exact idea of this malformation. 

_Causes_. --As was the case with the condition previously described, thisabnormality finds its primary cause in an unequal distribution of weightdue to vice of conformation in the limb above, causing one side of thehoof to be higher than the other. As a result of this, the wall that isinordinately increasing in height commences to bulge outwardly (Fig. 85, _a_), while the opposite (Fig. 85, _b_) becomes concave. 

The same state of affairs may be occasioned in the forge by leaving oneside of the foot too high, and subjecting the other to excessive paring forseveral consecutive shoeings. 

_Treatment_. --In the main this condition may be regarded as a long-standingand aggravated form of the foot with unequal sides. We may say at once, therefore, that it is not so easily remedied as that simpler defect; that, although identical principles will be followed in its treatment, cure mustbe a matter of some considerable time. 

[Illustration: FIG. 85. --SECTION THROUGH A CROOKED FOOT. _a_, The higherand convex side of the wall; _b_, the lower and concave side of the wall]

Again, we must look to successive parings of the wall of the higher side tobring about a gradual return to the normal. At the same time, the tendencyto contraction of that side is counteracted by shoeing wide, and, ifnecessary, giving to the upper surface of that branch of the shoe what wehave termed elsewhere a 'reversed seating'--viz. , an incline of its uppersurface from within outwards. 

CHAPTER VII

DISEASES ARISING FROM FAULTY CONFORMATION

A. SAND-CRACK. 

_Definition_. --A solution of continuity of the horn of the foot, occurringusually in the wall, and following the direction of the horn fibres. 

_Classification_. --It is usual to classify sand-cracks according to--

_(a) Their Position_. --_Toe-crack_ when occurring in the middle line of thehorn of the toe, and _quarter-crack_ when occurring in the horn of thequarters. 

Sand-crack of the frog and sand-crack of the sole may also each be metwith. They are, however, of rare occurrence, and are seldom serious enoughto merit special attention. 

The toe-crack is met with more often in the hind-foot than in the fore, while the quarter-crack more often than not makes its appearance in thefore-foot, and is there, as a rule, confined to the inner side. The reasonsfor these positions being so affected we shall deal with when treating ofthe causes of sand-crack in general. It is interesting to note that theportions of wall known as inside and outside toe are seldom affected. 

_(b) Their Length_. --_Complete_ when they extend from the coronary marginof the wall to its wearing edge; _Incomplete_ when not so extensive. 

_(c) Their Severity_. --_Simple_ when they occur in the horn only, and donot implicate the sensitive structures beneath; _Complicated_ whendeep enough to allow of laceration and subsequent inflammation ofthe keratogenous membrane. Such complications may vary from a simpleinflammation set up by laceration and irritation of the sensitivestructures by particles of dirt and grit that have gained entrance throughthe crack, to other and more serious changes in the shape of the formationof pus, hæmorrhage from the laminal vessels, caries of the os pedis, or thedevelopment of a tumour-like growth of horn on the inner surface of thewall known as a keraphyllocele. 

_(d) Their Duration_. --_Recent_ when newly formed; _old_ when of longstanding. 

_(e) Their Starting-point_. --This last distinction we make ourselves, and, referring to cracks of the wall, term them _high_ when commencing fromthe coronary margin, _low_ when starting from the bearing surface. 

_Causes_. --We have already classified sand-crack as a disease arising fromfaulty conformation. Thus, in just so far as a predisposing build of bodymay be handed down from parent to offspring, we may regard sand-crack ashereditary. If we do so, however, we must afterwards make up our mindsto sharply distinguish between the sand-crack plainly brought about byaccidental cause, and that occurring as a result of hereditary evilconformation. 

With regard to the latter, we need hardly say that feet with abnormallybrittle horn are extremely liable. But with this, as with many otheraffections of the feet, we shall find it necessary to consider severalcauses acting in cooperation. In this case, for instance, given the brittlehorn, it becomes necessary to further look for exciting causes of itsfracture. 

We will take conformation first. In the animal with turned-out toes a morethan fair share of the body-weight is imposed on the horn of the innerquarter. Here, then, three causes exert their influence together: The hornis brittle; the wall of the inner quarter is thinner than that of theouter; additional weight is imposed upon it. Fracture results. 

Take, again, the vice of contracted heels. Here, in the first place, wehave a variety of causes tending to bring about the contraction. With thecontraction, and its consequent pressure upon the sensitive structuresin the region of the quarters and the frog, has arisen a low type ofinflammation. The horn of the part has become dry and brittle. The excitingcause of its fracture is found in an excessive day's work upon a hard, dryroad, with, perhaps, a suddenly-imposed improper distribution of weight, due to treading upon a loose stone, or a succession of such evil transfersof weight due to travelling upon a road that is rough in its whole extent. 

In their turn, too, such defects of the feet as we have mentioned in thelast chapter--as, for example, the foot with the pumiced horn, the footwith abnormally upright heels, or that which is upright on one side only, or crooked--each offers a condition which is predisposing to the formationof a sand-crack. In each case it wants but the uneven distribution ofthe body-weight, which, as a matter of fact, some of these conditionsthemselves give, to bring about a fracture. 

Apart from the predisposition conferred by conformation, must be rememberedthe simpler predisposing causes leading to brittleness of the hoof. Werefer to the after-effects of poulticing, the moving from pasture tostable, the emigration from a damp to a dry climate, or the alternatechanges from damp to dry in a temperate region. Each may have adeteriorating influence upon the horn, rendering it liable to the conditionwe are describing. Excessive dampness alone, especially when the animal iscalled upon to labour at the drawing of heavy loads upon a rough road, isnot infrequently a cause. In this case the wet, together with the constantfriction of the sharp materials of which the road is made, serves todestroy the varnish-like periople. The wet gains access to the innerstructures of the wall, the agglutination of the horn fibres is weakened, and fissures begin to appear. 

Other causes of sand-crack are purely accidental. An animal at fast workover-reaches. The secretion of horn at the injured coronet is interferedwith, a diminished supply at an isolated spot being the result. From thispoint grows down a fissure in the wall. 

An injury of the same character may also be sustained in various otherways--treads from other animals when working in pairs, accidental woundingwith the stable-fork, blows of any kind, or a self-inflicted tread with thecalkin of an opposite foot--each with the same result. 

So far as causation is concerned, toe-crack stands in a class almost byitself. It is met with nearly always in a heavy animal in the hind-foot, and is directly attributable to the force exerted in starting a heavy load. 

Unskilful shoeing also plays a part in the causation of sand-crack. Removalof the periople by excessive rasping of the wall is most certainly apredisposing cause. Cracks, or their starting-points, may also be caused byusing too wide a shoe, or by the use of nails too large in the shank. Also, they may arise from unskilful fitting of the toe-clip, especially in thehind-foot of a heavy animal. It must be admitted, however, that the partshoeing plays in the causation of sand-crack is not a large one; far moredepends upon the state of the horn and the animal's conformation than uponthe exciting cause. 

So far, our observations on the causes of sand-crack have referred to thatform occurring in the wall. Sand-crack of the sole or frog we have alreadysaid is but seldom met with, and then it is always in connection with someexceptionally deteriorated quality of the horn, as in the case of badlypumiced feet, or occurs as a result of direct injury. Extensive slit-likecuts in this region, when deep enough to lacerate the keratogenousmembrane, are sometimes followed by the growth of a fissure in the horn, and what might almost be termed a permanent sand-crack results. Such cutsmay be occasioned by sharp flints, broken glass, or other sharp objectspicked up on the road, or may result from the animal treading on thetoe-clip of a partially cast shoe. 

_Symptoms_. --In every case the fissure, or evidence of its commencement, is a diagnostic symptom. It is well to remember, however, that this maybe easily overlooked, especially when the crack is one commencing at thecoronary margin. The reason is this: Sand-cracks in this position oftencommence in the wall proper, and not in the periople. They may, in fact, befirst observed as a fine separation of the horn fibres immediatelybeneath the perioplic covering. A crack of this description may even showhæmorrhage, and have been in existence for some time, without the periopleitself showing any lesion whatever. Thus, unless lameness is present, or amore than specially keen search is directed to the parts in question, thesand-crack goes undiscovered, until of greater dimensions. 

Further, the fissure may be hidden, either accidentally or of set purpose. It may be covered by the hair, filled in and covered over with mud, orintentionally concealed by being 'stopped' with an artificial horn, withwax, or with gutta-percha, or, as is more common, be hidden by the lavishapplication of a greasy hoof-dressing. 

In this latter connection it is well to warn the veterinary surgeon, especially the beginner, when examining for soundness, to be keenlycritical before passing an animal who is presented with feet smothered withtar and grease or any other dressing. More especially should this warningbe heeded when examining any of the heavier breeds of animal with anabundance of hair about the coronet. 

Referring again to the search for the crack, it is well to know that withtoe-crack the fissure is the more readily seen when the foot is lifted fromthe ground. With quarter-crack, on the other hand, the fissure is wider, and consequently the easier detected with the foot bearing weight. 

Although commencing in the insidious manner we have described, the lesionis not thus often seen by the veterinary surgeon. Usually, the animal withsand-crack is brought for his inspection when lameness has arisen from it. In this case the cause for the lameness will reveal itself in the crack, which is now too large to escape observation. The coronet is hot and tenderto the touch, and a sensation of warmth is sometimes conveyed to the handby the horn of the surrounding parts of the wall. It is hardly necessary tosay that, with accompanying conditions such as these, the sand-crack is a_deep_ one. 

Where the lameness is but slight, we may attribute it almost solely to thepain occasioned by the mere wounding of the keratogenous membrane, and tono very extensive inflammatory changes therein. By some authorities thisis said to be due to the pinching of the sensitive structures betweenthe edges of the fissure in the horny covering. In our opinion, however, pinching does not occur unless inflammatory exudation into the sensitivestructures adjoining the crack has led to sufficient swelling to cause themto protrude. In other words, the movements of the horny box, communicatingthemselves to the structures beneath, and so occasioning movement in thewounded keratogenous membrane, are quite sufficient to give rise to thelameness without actual pinching of the structures implicated. 

The severity of the lameness will vary with the rapidity of the gait, andwith the character of the road upon which the animal is made to travel. Forinstance, many animals in which the lameness is imperceptible at a walkbecome 'dead' lame at a fast trot. It is sufficiently explained whenone remembers the greater movements of expansion and contraction of theposterior parts of the wall brought about by the increase in the rate ofprogression. The same animal, too, will go distinctly more lame upon a hardthan upon a soft surface. 

In like manner the lameness from toe-crack also varies in degree with therate of progression and the character of the travelling, though not tosuch a noticeable extent as in the lameness from quarter-crack. A greatervariation may in this case be brought about by moving the animal onascending and descending ground. Descending an incline, with a more thanordinary share of the body-weight thus thrown upon the heels, the lamenessis most marked. The reason would appear to be that the greater expansionof the wall of the heels thus brought about leads to a proportionatecontraction of the wall at the toe, especially at the edges of the crack, thus causing undue pressure upon the exact spot of the wound in thesensitive structures. Ascending--the weight in this case transferred fromthe posterior to the anterior portion of the foot--the expansion ofthe heels becomes a contraction, with a corresponding lessening of thecontraction at the toe and a distinct decrease in the lameness. 

In the case of a deep but recent crack there is always more or lesshæmorrhage. This favours risk of infection of the lesion with pus-formingorganisms, and so leads to a more or less pronounced lameness, a degree ofswelling, heat and tenderness in the coronet above, and a certain amount ofsurgical fever. 

The acute symptoms subdued, but the fissure still remaining, gives us thecrack we have classified as 'old. ' This may in every case be distinguishedfrom a more recent lesion by the amount of thickening of the overhangingcoronet, and the presence of an increased quantity of sub-coronary horn inthe region immediately about the crack. The previous inflammatory changesin the adjoining sensitive structures have here led to an increasedsecretion of horn, and a greater or less deposition of inflammatoryconnective tissue in the wounded coronary cushion. 

Sand-crack of the toe always follows the direction of the horn fibres. Thatof the quarter, however, may on occasion run a course that is somewhatzigzag, first following the direction of the horn fibres for a shortdistance, then travelling in a horizontal direction, and finally continuingits course again in a line with the horn fibres, commonly at a pointposterior to that at which it commenced. 

In a quarter-crack that is old, and when contraction of the heels exists(which in this case it usually does), then will often be found overlappingof the edges of the crack. The expansion of the wall brought about when thebody-weight is on the heels, cannot, by reason of the break in it, continueitself anterior to the crack. As a consequence, repeated expansion of thewall posterior to the crack, with the portions anterior to it in a stateof enforced quiescence, leads in time to the posterior edge of the crackcoming to lie over that of the anterior. 

_Complications_. --The first complication likely to arise in a case ofsand-crack is that attending simple laceration of the sensitive structuresin a _deep_ lesion. With the laceration all the phenomena of a repairinginflammation make their appearance. As a result, there is more or less heataccording to the degree of inflammatory hyperæmia, swelling according tothe amount of inflammatory exudate, and pain according to the amount ofpressure the two foregoing bring to bear on the nerves in the inflamedarea. 

A second and more serious complication is the greater inflammation set upby the introduction into the crack of foreign substances. Small portions ofgravel and flint, both by the irritation set up by their friction and bythe infection they carry in with the dirt surrounding them, are responsiblefor the mischief. 

When, from direct communication with the blood-stream, due to extensivehæmorrhage, bacteria from the outside gain entrance, this simpleinflammation is further complicated by the formation of pus, or a limitedgangrene of the keratogenous membrane. 

In cases of great severity the gangrene of the keratogenous membranespreads until the deeper structures are involved. We then get a necrosis(in the case of toe-crack) of the extensor pedis, and sometimes caries ofthe os pedis. 

In like manner the necrotic changes occurring under these circumstances mayinvade the deeper structures in the region of quarter-crack. As a result ofthis, we may have the starting-point of suppurating corn, or necrosis ofthe lateral cartilage--in other words, cartilaginous quittor. 

Commonly accompanying quarter-crack is the condition of contracted heelsand atrophied frog. Sometimes described as a complication of sand-crack, itappears to us more rational to rather regard the sand-crack as a result orcomplication of the vice of contraction. 

The overlapping of the edges of the crack before referred to occasionallygives rise to the condition known as false quittor. A probe or a directorpassed beneath the overhanging ledge of horn reveals sometimes a fissure of1 inch or considerably more in depth, and quittor is diagnosed. A carefulparing away of the overhanging horn, however, reveals the true state ofaffairs, and exposes to view the original cause of the mischief--a simplefissure in the wall. 

A serious complication--one fortunately met with but rarely--is that ofkeraphyllocele. This is a tumour-like growth of horn, varying in size fromthe thickness of an ordinary quill pen to that of one's middle finger, growing down from the coronary cushion, and attached to the inner side ofthe wall of the hoof. With this lameness is always present, and more orless deformity of the hoof results. This condition will be found describedat greater length in Chapter IX. 

_Prognosis_. --In the case of sand-crack this should always be guarded. Itmay be taken as a general rule that cracks commencing from the coronarymargin are more troublesome to deal with than those originating below. Thereason is not far to seek. They here affect the wall just where the bevelin it for the accommodation of the coronary cushion has rendered itweakest. Not only is it weakest, but being more resilient than the portionsbelow it, it suffers more from the alternate movements of expansion andcontraction of the foot than does the horn below. 

Although in many cases a cure of the existing crack may be easilyaccomplished, regard should be paid to the possibility of its recurrence, either in the same position or elsewhere. Really, in offering an opinionas to the future usefulness of an animal so affected, a greater attentionshould be directed to the animal's conformation than to the crack itself. Where the vice of conformation giving rise to it (as, for example, contracted heels or upright hoof) gives hope of being remedied, thennaturally it may be safely said that the liability to sand-crack goes withit. 

A like favourable prognosis may be given in the case of cracks occasionedby purely accidental causes. 

Ordinarily, however, cracks once commenced tend rather to increase thandecrease in size and severity. From being superficial and incomplete, theybecome complete and deep, with every unfavourable circumstance that anincrease in size and depth brings with it. 

This much, however, may be promised to the owner. A simple crack, eventhough originating from the coronary margin, is, in the vast majority ofcases, curable. Under a rational treatment its increase in size may beprevented, and a sound wall caused to grow down from the coronet. 

_Treatment_. --The principles governing the treatment of sand-crack aresimple enough in themselves, if not always followed by success. 

1. _Preventive_. 

This, as a rule, does not suggest itself until a crack of greater or lessextent has made its appearance. Then, simultaneously with the treatmentproper of the lesion, preventive measures should be adopted, to aid both inthe healing of the fissure already present, and to ward off the occurrenceof others that might be likely to form. The hoof, if abnormally brittle, should be regularly dressed with a suitable ointment (one containingglycerine for preference), and its horn kept as nearly as possible ina normal condition. When the condition of the horn predisposing to itsfracture is brought about by excessive wet, then the appropriate preventivemeasures to be adopted suggest themselves. 

With regard to the lesion itself, we may term 'preventive treatment' allthose measures having for their object the prevention of increase in thesize of the crack. They are as follows:

_(a) Blistering the Coronet_. --In a simple case, where the crack issuperficial and close under the coronary margin of the wall, a sharpcantharides blister to the coronet immediately above it will have thedesired effect. An increased secretion of horn is brought about, and bythis simple means the crack prevented from becoming longer. Very often thisis all that is necessary. In fact, we may say here that, no matter whatother treatment is adopted, the simultaneous application of a blister tothe coronet is always beneficial. To derive full advantages therefrom, the blistering should be repeated several times at intervals of about afortnight. 

_(b) Clamping the Crack_. --When the services of a skilled smith are athand, one of the readiest methods of performing this is to draw the edgesof the crack together with an ordinary horse-nail. 

On each side of the crack a small horizontal furrow is burned or cut intothe wall, leaving the horn for about 1/4 inch on each side of the crackintact. This provides a groove for the ends of the clamping-nail to restin, and brings them flush with the outer surface of the wall. The nail isthen driven carefully home through the crack, and the pointed end graspedby the farrier's pincers. The edges of the crack are then drawn tightlytogether, and the nail firmly clenched. 

[Illustration: FIG. 86. --THE SAND-CRACK FIRING-IRON. ]

'The horse-nails are prepared in the ordinary way as for driving, with theexception that each is pointed on the reverse side, to prevent puncturingthe sensitive structures. Before being used the nails are put in a vice, and the head hammered to form a shoulder, to prevent their being driven toofar into the wall, and breaking out the hold. '[A]

[Footnote A: _Veterinarian_, vol. Xlviii. , p. 100. ]

Before driving the nail some operators burn or bore a hole for it. Opinionseems to differ as to whether this is at all necessary. 

A method of clamping which, on account of its simplicity, has becomegreatly popular, is that of Vachette. For this operation is needed theoutfit depicted in Figs. 86 and 87. 

[Illustration: FIG. 87. --THE SAND-CRACK FORCEPS AND CLAMP. ]

With the special firing-iron (Fig. 86) an indentation, sufficiently largeto admit the points of the clamp (Fig. 87), is made on each side of thecrack. The clamp is then adjusted, and pressed home tight by means of thesand-crack forceps (Fig. 87). According to the length of the crack, one, two, or three clamps may be necessary. Another useful clamp, though farmore complicated in its structure, is that of Professor McGill (Fig. 88). 

[Illustration: FIG. 88. --MCGILL's SAND-CRACK CLAMP. ]

'The object of this invention is to arrange on a spindle, which isscrew-threaded at one end with a right-hand thread and at the other with aleft-hand thread, two clips or clamps, free to travel on the thread, therebeing a nut between the two which can be turned by a spanner. The clipsare placed on the hoof, one on each side of the sand-crack, the hoof beingprepared to receive the instrument by filing a groove or notch for theclamps to fit into, and by turning the nut on the screw the clampsare brought towards each other, and the crack thus prevented fromspreading. '[A]

[Footnote A: _Veterinarian_, vol. Lxi. , p. 141. ]

Still a further useful clamp is that of Koster. This is considerablybroader than the clamp of Vachette, and its gripping edges are providedwith teeth (see Fig. 89). 

As with the clamp of Vachette so with this, a groove is burned into thewall on each side of the crack for the accommodation of the jaws of theinstrument, and the clamp itself pressed home by means of a special pair offorceps. This form of clamp holds well, and has the advantage of securing awider area of horn than that of Vachette or McGill. 

[Illustration: FIG. 89. --KOSTER'S SAND-CRACK CLAMP. ]

Clamping by any method should be advised or undertaken only under certainconditions. The horn should be moderately strong, and the wall should bethick. This practically restricts the use of the clamp to cracks of thetoe, and it is there, as a fact, they are found of most benefit. Whileburning the grooves for the clamp, and while tightening the clamp itself, the animal's foot should be on the ground and bearing weight at the heels, thus insuring the greatest possible approximation of the edges of thecrack. 

With all methods of clamping an untoward result is sometimes the formationof a fresh crack at the point of insertion of the clamps. 

(c) _By the Use of Thin Metal Plates_. --These are of use when the horn ofthe wall is too thin to allow of clamping, and are therefore of especialuse in cracks of the quarters. The plates are made so as to cover thegreater part of the length of the lesion, and are fastened to the wallby two or more screws on either side of the crack. It is an advantage toslightly let the plate into the wall by means of fitting it hot. In acomplicated crack the plate serves the further useful purpose of holding inposition antiseptic pledgets, and so keeping the lesion free from dirt andgrit. 

_(d) By Various Methods of bandaging the whole Circumference of theWall_. --In our opinion this method of attempting to secure immobility ofthe crack, and so prevent its extension, is not often followed by success. The main objection to the method is that it subjects the whole of the wallto the same pressure, and does not restrict the operation to the point atwhich it is required. As in the case of the metal plate, however, thismethod has the advantage that antiseptic dressings may be kept in positionin the case of a complicated crack. 

[Illustration: FIG. 90. --SAND-CRACK BELT. ]

The binding of the wall may be accomplished in two ways. The simpler of thetwo is to merely apply the sand-crack belt depicted in Fig. 90. Beneaththis should be applied a compress of tar and tow or other material, and thewhole tightened up and kept in position by means of the buckle and strap. This method of binding admits of after-tightening should it unfortunatelywork loose. 

The older method of binding the wall, and one now often practised by thesmith, is to use a quantity of so-called 'tar-band' or other stout cord. With this the foot is neatly bound after the manner of a cricket-bathandle, and all movement of the crack apparently restricted. There isalways a tendency, however, for such a dressing to work loose, and in thecase of a complicated crack it has the disadvantage of permanently hidingfrom view the changes taking place in the discharge from the fissure. 

_(e) By wedging the Crack_. --This is the exact opposite of clamping. Whereas in clamping we obtain immobility of the crack by keeping it fixedin the position of greatest approximation of its edges, in wedging, thecrack is rendered free from movement by maintaining it in that positionwhere its edges are most widely separated. In this case the edges of thecrack are pared smooth, the cavity thoroughly cleansed, and a wedge of hardwood firmly driven in so as to fit exactly the fissure. 

On the face of it it appears that this procedure would really tend to forceopen and so lengthen the crack, especially at its coronary extremity. Whatone should really remember, however, is that the crack _is not made wider_than before, but that it is simply maintained in a position occurring withevery contraction of the heels of the foot, when it is normally atits widest. Movement of the edges is thereby stopped, the immediatelysurrounding structures are rested, and a new growth of horn, free fromcrack, induced to grow down from the coronet. 

This method of treatment only serves to emphasize the fact that, with asand-crack once formed, it is the constant movement of the parts that tendsmost to keep it in existence, and not any particularly marked exertion offorce. 

Some practitioners, with the wedge, apply also a clamp, thus assuringadditional firmness and solidity to that portion of the wall undertreatment. 

The method of wedging is undoubtedly successful, if neatly performed. 

_(f) By Surgical Shoeing_. --A partial rest is given to the affected partsby easing the bearing of the shoe at the point required. This may be doneeither by removal of part of the wall at the spot indicated, or by thinningthe web of the shoe in the same position. The former is the method usuallypractised. Cessation of movement given in this way is, as we have alreadysaid, only partial; for, while the effects of pressure and concussion frombelow are minimized, the crack is still able to suffer from the movementsof expansion and contraction of the foot. Still, as an auxiliary to othertreatments, 'easing' of the wall under the affected part should always bepractised. 

[Illustration: FIG. 91. ---THE BEARING 'EASED' BY REMOVAL OF THE WALL. ]

[Illustration: FIG. 92. --THE BEARING 'EASED' BY THINNING THE WEB OF THESHOE. ]

Figs. 91 and 92 show respectively the manner of 'easing' by removal ofthe wall, and by thinning the web of the shoe. In this connection it isnecessary to point out that on no account should 'springing' of the heelsof the shoe be allowed. Fig. 93 illustrates the ill-practice. 

In this case, when the entire weight is thrown on to the heels, the portionof wall posterior to the crack is bound to participate unduly in thedownward movement, and so tend to widening of the crack at its highestpoint. 

[Illustration: FIG. 93. --THE BEARING 'EASED' BY 'SPRINGING' THE HEEL OF THESHOE. ]

We have already referred to the matter of 'clips. ' In no case, whether thecrack be at the toe or in the quarters, should a clip be placed immediatelybelow it. If the crack is at the toe, the usual clip should be dispensedwith, and a clip at each side made to take its place. At the same time careshould be taken to avoid throwing the weight far forward. For that reasona shoe with calkins or with very high heels should be removed, and a shoewith an ordinary flat web substituted. 

In the case of quarter-crack, where the constant movement of the partsunder expansion and contraction of the foot makes itself most felt, it iswise to apply a shoe with clips fitting moderately tight against theinside of the bars. By this means movement will to a very large extent becurtailed. 

Where a marked tendency to contraction is found, as is often the case withquarter-crack, then the shoe with the clips may be rendered more marked inits operation by giving to the outer face of each clip--that face appliedto the bar--a slope from above downwards and outwards. In other words, aslipper shoe should be applied and the contraction given equally as muchattention as the sand-crack itself. 

Where the crack is situated far back in the quarter, and easing of thebearing cannot be accomplished without tending to spring the heels, thenthe most suitable shoe is a bar shoe. With it the bearing may, of course, be eased in exactly the position required, and the heels still allowedto take their fair share in bearing the body-weight, and thus assist inclosing the crack. The bar shoe, if properly fitted, gives us also abearing on the frog, and aids greatly in counteracting contraction. 

2. _Curative_. 

_(a) The Application of Dressings to the Lesion_. --In the case of a recentcrack, deep, and attended with hæmorrhage, the foot should be thoroughlycleansed. Where possible, a constant flow of cold water from a hose-pipeshould be allowed to run over the foot. By this means the inflammatorysymptoms will be held in check and pain prevented. Later the shoe may beeased at the required place, and a blister applied to the coronet. This, with rest, will sometimes prove all that is needed. 

Should a crack be of old standing, and complicated by the presence of pus, a course of hot poulticing will often prove of benefit. The poultice shouldbe medicated with any reliable disinfectant, and should be renewed, or atany rate reheated, two or three times daily. The crack itself should bethoroughly cleaned after the removal of each poultice, and a concentratedantiseptic solution--such as Tuson's spts. Hydrarg. Perchlor. , carbolicacid, and water, (1 in 10) or liquor zinci chlor. --poured into it. Ondiscontinuing the poulticing, the strength of the antiseptic solutions maybe decreased, the parts rested by correct shoeing, and a blister applied tothe coronet as before. 

If these measures alone should prove insufficient, then the surgeon willeither fall back on those we have just related, or proceed to methods nextto be described. 

_(b) Immobilizing the Crack by Means of grooving the Wall_. --To ourminds, this is as ready and withal as successful a method of dealing withsand-crack as has yet been devised. It may be done in a variety of ways:(1) By two grooves arranged about the crack in the form of a V, as Fig. 94;(2) by a perpendicular groove on either side of the crack, about 1 inch indistance from it, and parallel with the horn fibres, as Fig. 95; (3) by asingle horizontal groove at the extreme upper limit of the crack; (4) bydrawing two horizontal grooves, one at its upper and one at its lower end(see Fig. 96). 

[Illustration: FIG. 94, FIG. 95, FIG. 96. In Figs. 94, 95, and 96 the thickblack lines illustrate the positions of the various grooves made with thefiring-iron for the purpose of immobilizing a quarter sand-crack. ]

The points to be observed in carrying out this line of treatment are simpleenough. In all cases see that the crack is rendered as clean as possibleby the use of suitable dressings, and if an excess of horn is presentimmediately around it, as in the case of a long-standing and complicatedlesion, have it thinned down by rasping. 

All that is then needed is one or two moderately sharp, flat firing-irons. The groove is then burned into the horn in the positions indicated, andthat portion of the wall containing the sand-crack thus prevented fromparticipating in the movements of the foot. For our own part, we considerthe V-shaped incision, or either of the horizontal methods of grooving, preferable to lines running in the direction of the horn fibres. With thelatter there is certainly a greater tendency to the formation of new cracksthan with either of those we advocate. The V-shaped incision we considermost suitable of all, for the reason that by its means a greater degree ofimmobility is conferred upon the necessary portion of the wall. 

Whichever method is adopted, care should be taken to carry the grooves deepenough into the horn, taking them down as near as possible to the sensitivestructures. At the same time, especial care should be exercised in notcarrying them too deep at their extreme upper limit, or in that case theliability to the formation of fresh cracks in those positions will begreatly increased. 

After grooving, a sharp blister should be applied to the coronet everythree or four weeks, and the animal, if free from lameness, put to work. 

_(c) By stripping away a V-shaped Portion of the Wall around theCrack_. --This method is only indicated when the crack is greatlycomplicated by the presence of pus, or by the growth of adventitious hornon the inner surface of the wall. A radical cure is thus obtained, but theanimal for a longer time incapacitated from work. 

The operation is best performed by first grooving a line to connect thepoints _a_ and _c_ (Fig. 97). This should run immediately under thecoronary margin of the wall, and should stop short of injuring the coronarycushion beneath. Grooves forming the sides _ab_ and _bc_ of the triangularpiece of horn are next made, and the horn contained within the lines _ab, bc_, and _ca_, carefully removed. The grooves are the easiest made by acautious use of the firing-iron. The greater thickness of the horn maythus be penetrated, and the grooves afterwards carried to their full andrequisite depth by the use of the drawing-knife. 

With the removal of the horn the diseased structures are exposed to view. All such should be removed by a free use of the scalpel, and a suitabledressing afterwards applied. A necessary factor in the treatment is theemployment of pledgets of antiseptic tow. With these the exposed tissuesare covered, and the successive turns of a bandage run tightly overthem, so as to exert a moderate degree of pressure. When hæmorrhage hasaccompanied the operation, this dressing should be removed on the followingday, the wound dressed, and the pledgets of tow and the bandage renewed. Any after-dressing need only then be practised at intervals of a week. Repair after this operation is rapid, and takes place both from the exposedpodophyllus membrane and from the coronary cushion. 

[Illustration: FIG. 97. The dotted lines outline the V-shaped portion ofwall to be removed in the treatment of complicated toe-crack. ]

[Illustration: Fig. 98. The dotted lines indicate the portion of wall to beremoved in the complete operation for complicated toe-crack. ]

_(d) By stripping the Wall from the Coronary Margin to its wearing Edge onEither Side of the Crack_. --This is merely a more extensive applicationof the method just described, and is only indicated in a _complete_ and_complicated_ crack that has refused to yield to other modes of treatment(see Fig. 98). 

As in the previous case, a groove is run from _a_ to _c_. The grooves _ab_and _de_ are then continued to the lowermost edge of the wall, and thewhole of the wall within these points removed. To facilitate removal, the white line should be grooved between the points _b_ and _d_. After-treatment is exactly the same as that just referred to. 

B. CORNS. 

_Definition_. --In veterinary surgery the term 'corn' is used to indicatethe changes following upon a bruise to that portion of the sensitive solebetween the wall and the bar. Usually they occur in the fore-feet, and arethere found more often in the inner than in the outer heel. 

The changes are those depending upon the amount of hæmorrhage and theaccompanying inflammatory phenomena occasioned by the injury. 

Thus, with the hæmorrhage we get ecchymosis, and consequent red stainingof the surrounding structures. As is the case with extravasations of bloodelsewhere, the hæmoglobin of the escaped corpuscles later undergoes aseries of changes, giving rise to a succession of brown, blue, greenish andyellowish coloration. 

With the inflammation thereby set up we get swelling of the surroundingbloodvessels, pain from the compression of the swollen structures withinthe non-yielding hoof, and moistness as a result of the inflammatoryexudate. 

In a severe case the inflammation is complicated by the presence of pus. 

_Classification_. --Putting on one side the classification of Lafosse_(natural_ and _accidental_), as perhaps wanting in correctness, seeingthat all are accidental, and disregarding the suggested divisions of Zundel_(corn_ of the _sole_ and _corn_ of the _wall_) as serving no practicaluse, we believe, with Girard, that it is better to classify corns accordingto the changes just described. 

Following his system, we shall recognise three forms: (1) _Dry_, (2)_moist_, (3) _suppurating_. 

The _dry_ corn is one in which the injury has fortunately been unattendedwith excessive inflammatory changes, and where nothing but the colorationimparted to the horn by the extravasated blood remains to indicate what hashappened. 

The _moist_ corn is that in which a great amount of inflammatory exudate isthe most prominent symptom. It indicates an injury of comparatively recentinfliction. 

The _suppurating_ corn, as the name indicates, is a corn in which theinflammatory changes are complicated by the presence of pus. 

_Causes_. --The causes of corns we may consider under two headings--namely, _predisposing_ and _exciting_. 

_Predisposing Causes_. --By the heading of this chapter we have alreadyintimated that corns are due to faulty conformation of the foot. It is, therefore, merely a description of such shapes of foot as favour theirformation that will need mention here. 

The wide, flat foot, with low heels, may be first considered. Here theposterior portions of the sole, those portions between the wall and thebars, fall very largely in the same plane as the wearing surface of thebars and the wall. As a consequence, these portions of the sole are moreprone to receive injury from stones and rough roads and from the pressureof the shoe. 

The low heels, too, favour a more than due proportion of the body-weightbeing thrown on to the posterior parts of the foot. Two evils, bothinclining to the production of corn, result from this. In the firstplace, the sensitive structures of the posterior portions of the foot aresubjected to undue pressure from above; secondly, the posterior half ofthe foot, by reason of the extra weight thrown upon it, is exposed also togreater effects of concussion than normally it should meet. Added to thiswe find that the abnormally flat condition of the sole has resulted ina great loss of resiliency. With undue pressure above, and a loss ofresiliency and added effects of concussion below, the sensitive structuresincluded between the opposing pedal-bone and the horny sole are boundto suffer more or less bruising each time the foot comes to the ground, especially if the animal is moved at a rapid pace. 

Writing here of the effects of pressure and concussion affords a fittingoccasion to mention the fact that corns occurring in feet affected withside-bones are always worse than in feet with normal elastic cartilages. The explanation of this is simple, for there can be no doubt that theloss of resiliency in the diseased cartilage is only another aid to unduepressure and concussion. The sensitive structures are pinched betweenunyielding bone above and practically unyielding horn below. 

Feet with high and contracted heels are also predisposed to corn. Thecontraction in this case interferes with the downward movements of the ospedis during progression, while in a state of rest there is a more orless constant pressure upon the sensitive structures, due to the correctdownward displacement of the pedal-bone being opposed by the amount ofcontraction present. In the contracted foot, too, the nutrition of thevessels supplying the secretory apparatus of the horn is largely interferedwith. The horn loses its natural elasticity, fails to respond to the normalmovements of the parts within, and aids in the compression and lacerationof the sensitive structures. 

Weak feet, with horn too thin to withstand the expansive movementscontinually going on--in other words, feet with weak, spreading heels--arealso prone to suffer from corns. In this case the flatness induced by thespreading, and the insufficient protection afforded by the thin horn, both combine to lay the sole open to the effects of concussion and directinjury. 

Brittle feet--feet with horn of undue dryness, by reason of the contractionthus brought about--are, again, particularly subject to corn. 

So also with long feet. Whether occurring as a natural deformity, or as theresult of insufficient paring, bruises of the sole in feet thus shaped arecommon. The reason for this will be better understood when we come to dealwith the shoeing. 

Other and minor predisposing causes are those mainly referring to anunnatural dryness of the hoof when animals reared in the country are putto work in large towns. We here really get several predisposing causescombining. A sudden change is made from a more or less moist conditionunderfoot to one excessively dry. The character of the travelling is whollyaltered from occasional work upon soft lands to continual labour uponhard-paved roads. The horn is often exposed to the vicious influencesof unsuitable litter, the application of unsuitable dressings, and thedeleterious effects of the street mud of our cities. All these play theirpart in determining a condition of the horn, rendering it open to receivethe effects of the more exciting causes which we shall next consider. 

_Exciting Causes_. --Than the shoeing, no more frequent and exciting causeof corn exists. Whatever the predisposing influences may be, it is theshoeing that in nearly every case completes the list, and finally inflictsthe injury. 

The evils in this connection we shall consider under two headings--viz. , (1) the manner in which the foot is pared; (2) the make and fitting of theshoe. 

First among the faulty preparations of the foot comes that of excessivethinning of the sole, especially in the regions subject to corn. Thefarrier addicted to this is not as a rule content to confine his operationsto the sole alone. In addition, the frog and the bars also suffer from thetoo lavish use of his knife. His main object is doubtless that of givinga broad and open appearance to the foot. It follows from this that hisoperations are confined more to the posterior than the anterior parts ofthe foot, and that the toe is therefore left too long. This gives us acombination of causes leading to pressure and bruises upon the sensitivestructures at the seat of corn. 

By this unequal paring of the toe and the heels greater weight is thrownupon the posterior half of the foot. What then happens to the structuresthinned as we have described is this: the pared frog, lessened in volume, does not meet the ground. It therefore fails to expand laterally withweight, and cannot assist, as normally it should, in aiding the heelsgenerally in their movements of expansion. The weakened bars and thethinned sole, meeting with no opposition from the frog, give downwards andinwards with the body-weight at the precise moment these movements shouldbe directed mainly outwards. As a further result of non-resistance on thepart of the frog, this time in a lateral direction, the bars, the sole, andthe wall at the heels all contract at the exact time they should expand. The end result must mean abnormal pressure and bruising of the sensitivestructures in that particular region. Naturally, also, the excessivethinning of the horn renders direct injury to the sole from stones or otherobjects in the road far more probable. 

For this one reason alone--the manner in which it favours the production ofcorn--too great a condemnation cannot be placed upon excessive paring ofthe sole, the bars, and the frog. 

When corns are already present, as they may be from other causes, the sameremarks will again apply to excessive paring. It is the custom with manysmiths to carefully pare down the discoloured horn in every case of cornthey meet with, and at the same time to again weaken the bars and even partof the wall at the heels, with the laudable idea of relieving pressure onthe part diseased. After what has gone before, we need hardly say thattheir well-meant efforts have a precisely opposite effect to the one theyintend. 

The fitting of the shoe is, perhaps, to a greater extent responsible forthe causation of corn than is the paring we have just described. 

A few of the evils connected with the shoe may, however, be justlydescribed as unavoidable. We _must_ shoe; we cannot shoe and leave a normalfoot!

A shoe excessively seated, especially from the last nail-hole backwards, may be regarded as dangerous. In this case, with every application of thebody-weight, there is given to the foot a tendency to contract, especiallyat its lower margin. Result: undue pressure upon the tissues around and theproduction of corn. 

On the other hand, varying with the form of foot, the seating may beinsufficient. In the case of flat-foot, or dropped sole, for instance, insufficient seating will lead to undue pressure of the web of the shoeupon the sole, and in that way bring about bruising of the sensitive solebeneath. 

Shoes with heels or calks too high, by destroying the counter-pressure ofthe frog with the ground, serve to bring about a series of changes we havedescribed under contraction, and again result in pinching and bruising ofthe sensitive structures. 

The opposite excess--a shoe thick at the toe and thin at the heels--isblamed by Zundel for causing a like injury. In our opinion, the reason thisauthor gives--namely, that the throwing of greater weight upon the heelsleads to bruising of the sensitive structures--can only correctly apply toa _wrongly-applied_ shoe of this type, and not to the shoe itself. True, ashoe with a thick toe and thinned heels will throw an undue proportion ofthe body-weight upon the heels if the foot is not properly prepared forit. A wise man, however, will most certainly so cut down the toe for thereception of this shoe that, with the shoe in position, there will still bemaintained a tread that is normal. To our minds harm is far more likely toarise from a shoe of this class through the thinned iron heels of the shoebecoming attenuated under wear to the point of bending, and so inflictingan injury upon the adjoining sole. 

Similarly, this last remark with regard to the thinning of the heels of theshoe will apply to a shoe with too broad a web. As the thinning of the shoeproceeds with wear, the inner portion of the thinned branch is bent up onto the sole, and again inflicts the injury. 

The matter of bearing is also of importance when considering the causationof corn. In a previous chapter we have already described the correctbearing as that which includes the whole of the lower margin of the walland the white line, and just impinges on the sole. Any marked deviationfrom that will, if long continued, be followed by injury to the foot. 

With the bearing surface of the shoe too narrow--in contact with thewall solely, or perhaps only a portion of it--it is evident that a largeproportion of the foot that should properly bear weight is thrown out ofaction. A heavy strain is imposed on the white line, and undue descent ofthe sole and contraction of the heels brought about. Again the result ofthis is compression and bruising of the tissues around the seat of corn. 

With its bearing surface too wide, the shoe immediately exerts directpressure upon the sole with every movement of the animal. The sole normallyis not made to receive this, and harm is bound to result. 

Among other ill-fitting shoes we may mention the one with branches tooshort, and the one with the extremities of the branches too pointed. Inthe first case, as wear of the shoe proceeds, the thinned end is far morelikely to turn in under the seat of corn than is a shoe with branchesof ordinarily correct length. It is evident in the second case that thepointed branch, when thinned, is a more dangerous agent than the branchwhich is nearer the square at its end. 

The matter contained in the first half of the foregoing paragraph explainsin a large measure the rarity of corns in the hind-feet. Here there isnothing to prevent a shoe with branches of full length being used. Thecorrect bearing is thus maintained, even with a shoe excessively thinnedwith wear, and the liability to injury from it decreased. An exception isto be found in the case of a feather-edged shoe, such as is used to preventcutting or brushing. The thinning by wear from above to below of the branchalready purposely thinned from side to side leads to the formation of athin and narrow piece of iron admirably calculated to bend over and injurethe sole. 

Even with a shoe of correct length, with a flat-bearing surface at theheels, and other conditions favourable to correct application, evil maystill result from the shoe itself being made too narrow. As a resultof this, the branch of _each_ side is set too far under the foot, withconsequent injury to the sole. This is, of course, sheer carelessnesson the part of the smith. When practised, however, it is not easy ofdetection, as in all cases the foot is rasped down to cover what has beendone. In other words, the foot is made to fit the shoe and not the shoe thefoot. 

Recognising this close fitting of the shoe as a cause, we are able toexplain in some measure how it is that corns should occur with greaterfrequency in the inner than in the outer heel. There is no doubt that theinner branch of the shoe is nearly always fitted closer than is the outer. In the fore-foot it is also often shorter. Take these two evils and addto them the fact that the inner heel is called upon to bear more of thebody-weight than is the outer, and the frequency of corns in the inner heelwill no longer be wondered at. 

Indirectly, the shoe may still be a cause of corn by reason of theirritation set up by gravel and small pieces of flint becoming firmly fixedbetween the sole and the web of the shoe. In nearly every case of thisdescription the part to be injured is the white line. 

Corns may also result from the animal picking up a stone. The stone becomesfirmly wedged in between the inner border of the branch of the shoe and thebar or the frog. With every step the animal takes it becomes wedged moretightly into position. Projecting below the level of the lower surface ofthe shoe, it imparts the concussion it thus obtains directly to the sole. Abruise--and a bad bruise--is the result. 

Finally, it cannot be denied that the work the horse is put to is largelyresponsible for the causation of corn. In country animals corns arecomparatively rare, while in animals in town, almost constantly upon hardpaving, they are common. This seems to point strongly to the fact thatconcussion through constant work upon unyielding roads is a great factor intheir production. 

_Symptoms_. --Unless the discoloration of the horn is accidentallydiscovered by the smith, the simple, dry corn may go undetected. Thedisturbance excited by it is so small, and the pain occasioned so slight, that the patient may offer no indication of its existence. 

Ordinarily, however, the first symptom is that of pain. The animal goesfeelingly with one or both feet, in some cases even showing decidedlameness. The lameness, however, is in no way diagnostic, and the lesionitself must be discovered before an exact opinion can be pronounced. 

As an aside, it is well to observe in this connection that a negativeopinion as to the existence of corn should never be given unless thesuperficial layers of horn have first been removed with the knife. 

When standing at rest the animal exhibits signs more or less common to allfoot lamenesses. He 'points' the foot--in other words, the limb is slightlyadvanced, the fetlock partly flexed, and the heels from off the ground. When both feet are affected they are pointed alternately, and the animaloften manifests his uneasiness by repeated pawing movements, and byscraping his bedding behind him. 

Should the injury run on to suppuration, the lameness becomes mostacute. The pawing movements become more pronounced, and there is evidentdisinclination on the part of the animal to place the foot squarely on theground. One is then led to manipulate the foot. The hoof is hot to thetouch. Percussion causes the animal to flinch, and to flinch particularlywhen that portion of the wall adjoining the corn is struck. Finally, exploration with the knife reveals the serious extent to which the injuryhas developed. In a neglected case of this description it is even possibleto detect the presence of pus by the amount of swelling and fluctuatingcondition of the coronet. The suppurative process has advanced in thedirection of least resistance, and is on the point of breaking through thetissues immediately above the horn. 

Lameness due to corn is oftentimes intermittent. With a simple corn, dry ormoist, this intermission is largely dependent on the degree of dryness ofthe hoof or the road, and also on the character of the road surface. With aneglected, suppurating corn, on the other hand, variation in the degreeof lameness, in addition to depending on circumstances such as these, is dependent to a larger extent upon the changes occurring with thesuppuration. In this case the time of greatest lameness is immediatelybefore the pus gains outlet. Immediately after its exit at the coronet theanimal will go almost sound. Soundness continues so long as the opening atthe coronet remains clear. The tendency, however, is for the opening thusmade to quickly close again. Pus again accumulates, lameness arises asbefore, and disappears again with the second discharge of the contents ofthe sinus now formed. 

_Pathological Anatomy_. --When dealing with their classification we gave inoutline the main pathological changes to be met with in corns. It now onlyremains to give the same matter in slightly greater detail. 

_In dry corn_ the changes we meet with are those accompanying bloodextravasation. From excessive compression of the parts, or from the effectsof direct injury, a portion of the sensitive sole has become lacerated. The escaping blood stains the surrounding soft tissues after the mannerof blood extravasation elsewhere. If the escape of blood is sufficientlylarge, the horn fibres in the immediate vicinity also are stained. It isthis stain in the horn that is the direct evidence of the injury, and isitself popularly known as the corn. It may vary in size from quite a smallspot to a broad patch as large as half a crown, while its colour may be auniform red, or a mottled red and white. The microscopic changes in thisconnection are illustrated in Fig. 99. 

[Illustration: FIG. 99. --HORIZONTAL SECTION OF A CORN. The section cut atabout the base of the papillæ of the sensitive sole. _a_, papillæ, withhorn-cells surrounding them; _b_, interpapillary or intertubular horn;_c_, hollow spaces in the intertubular material filled with blood; _d_, apapilla and its surrounding horn-cells filled with blood. ]

Ordinarily, this ecchymosis of the horny sole is due to injury of thesensitive sole _immediately beneath_ it. It may, however, proceed frominjury to the vessels of the laminæ either of the bars or of the wall. Inthis case the ecchymosis of the horny sole may be explained by the factthat the escaped blood tends to _gravitate_ to that position. 

When the corn is of long standing, or is due to _repeated_ injuries on thesame spot, the horn adjacent to the lesion becomes hard and dry, and oftenabnormally brittle, simply on account of the inflammatory changes thus keptin continuation. This is often seen when attempts are made to _pare out_the corn with the knife. 

Should the injury be seated in the sensitive laminæ, then the brittlenature of the horn secreted by the injured tissues makes itself apparent bythe appearance of cracks in the wall of the quarter. Why this should occurwill be readily understood by a reference to Fig. 100. 

[Illustration: FIG. 100. --INNER SURFACE OF THE WALL OF THE QUARTER, SHOWINGCHANGES IN THE HORNY LAMINÆ BROUGHT ABOUT BY CHRONIC CORN. ]

It will here be seen that the injury to the keratogenous membrane has ledto great interference with the secretion of horn from the sensitive laminæ. As a result, the regularly leaf-like arrangement of the horny laminæ hasbeen largely broken up. Certain of the laminæ are altogether wanting, while others are broken in their length and rendered incomplete. With thiscondition there is always more or less contraction of the quarter. 

Microscopic examination of the structures involved in such a case revealsthe fact that with the contraction is an alteration in the normal directionof the horny and sensitive laminæ. 

They become bent backward, and, instead of the regular and normalarrangement depicted in Fig. 32, show the distorted appearance given inFig. 101. 

From the appearances and characters of the blood-stain in the horny solewe are able to deduce evidence relative to the duration and nature of theinjury. 

[ILLUSTRATION: FIG. 101. --PERPENDICULAR SECTION OF THE WALL OF A CONTRACTEDQUARTER IN A CASE OF CHRONIC CORN. Both the sensitive and horny laminæare bent backwards, and hæmorrhages have taken place at the base of thesensitive laminæ. ]

When, for instance, the stain is not to be found in the superficial layersof the sole, but is only discoverable by deep paring, then the injury is arecent one. 

Where the stain _is_ met with in the superficial layers of horn, and isquickly pared out, then the injury has been inflicted some time before, andhas not been repeated. When, as is sometimes the case, layers of horn thatare stained are found alternated with layers that are healthy, then we haveevidence that the cause of the corn, whatever it may be, is not in constantoperation. 

Similar indication of the age of the injury is also afforded by the colourof the lesion. 

A stain that is deep red is proof that the injury is comparatively recent. 

A distinct yellow or greenish tinge, on the other hand, is evidence thatthe injury is an old one. 

_In the Moist Corn_ we have, in addition to the blood extravasation, theoutpouring of the inflammatory exudate. In the most superficial layer ofthe horn this may not be noticeable. As one cuts deeper into the sole withthe knife, however, it will be found that the lower layers of horn aremore or less infiltrated with the discharge. This gives to the horn a softconsistence, a yellow appearance, and a touch that is moist to the fingers. 

With the accompanying inflammation the cells in the neighbourhood of theinjury are enfeebled and their normal functions interfered with. We maythus expect a corresponding interference with the growth of horn. This isexactly what happens, and as one cuts deeper still into the horn a point isfinally reached when a well-marked cavity is encountered. A pale yellowand usually watery exudate fills it. This cavity points out the exact spotwhere the force of the injury has been greatest, where death of certaincells of the keratogenous membrane has resulted, and where the naturalformation of horn has for a time been suspended. 

_In the Suppurating Corn_, as in moist corn, we have pathological changesdue to the tissue reaction to the injury, _plus_ the addition of pusorganisms. Confined within the horny box we have a discharge that, byreason of the living and constantly multiplying elements it contains--thepus organisms--is always increasing in bulk. This must be at the expenseof the softer structures of the foot. Accordingly, as the formation of pusincreases, we get pressure upon and final gangrene of the sensitive soleand of the sensitive laminæ of the bars and the wall. With no outlet below, the pus formation increases until finally it finds its way out of the hoofby emerging at the coronet. 

This in some instances it may do by confining its necrotic influencessolely to the sensitive laminæ of the wall, in which case, if a dependentorifice is quickly made at the sole, the injury to the laminæ is soonrepaired by the healthy tissue remaining. 

In other cases, however, the necrosis has spread deeper. Caries of theos pedis, of the lateral ligaments of the pedal-joint, or of the lateralcartilages, is a result. When this occurs the exuding discharge from thecoronet becomes thinner and more putrescent, and its feel, when rubbedbetween the fingers, sometimes gritty with minute fragments of broken-upbone. Here, unless operative measures prevent it, necrosis soon spreadsdeeper still. The deeper portions of the os pedis become affected. Thecapsular ligament of the joint is penetrated by the suppurative process, and a condition of septic arthritis results. The cavity of the jointbecomes more or less tensely distended, according to the amount of drainagepresent, which in this case is almost nil, with matter in a state ofputrescence. As a consequence, the surrounding ligaments become softenedand yield, and the articular surfaces displaced. The articular cartilagesalso suffer, become necrotic in patches, and frequently wholly destroyed. The end result is one of anchylosis of the joint and permanent lameness. 

_Prognosis_. --With the ordinary dry corn a return to the normal may nearlyalways be looked for. Similarly, with moist corn, and even with carefultreatment of the suppurating variety, the same favourable termination maybe looked for and promised. 

What cannot so safely be assured is that a relapse will not occur. In otherwords, the extent of the injury, no matter how serious, does not oftenoffer anything that cannot be overcome by Nature and careful surgery; butthe conformation of the animal does. A vicious predisposing conformationonce there is there always, and although the injury resulting from it mayeasily give way to correct treatment, the same injury is bound to re-occurwhen the animal is again put to work. 

Although with care suppurating corn, like other cases of suppurationwithin the hoof, may yield to treatment, the owner of the animal should, nevertheless, be warned that the condition is a serious one, especiallyshould the joint become affected. It may so happen, as sometimes in fact itdoes, that the animal may die as a result of the infective fever so set up. From no surface in the body can absorption take place quicker than from thesynovial membrane of a joint. So soon, therefore, as this membrane comes incontact with septic material, so soon does a severe septic fever make itsappearance. The septic matter has gained the blood-stream, and the patientsuccumbs to septic poisoning. 

Apart from death occurring naturally, the changes taking place in the jointin the shape of bony growths or of actual anchylosis may be so severe as torender the animal useless, and slaughter may have to be advised. 

_Treatment_. --We have already said that by far the most active cause inthe production of corn is the shoe. It follows from this that it is to theshoeing we must largely look for a successful means of their prevention, and that the treatment of corn in its most simple form is really a matterfor the smith, and not for the veterinary surgeon. 

The faults in connection with the shoeing we have mentioned fully whentreating of the _causes_ of corn. From those we learn that a shoe with aflat-bearing surface, or one moderately seated but flat at the heels, isthe correct shoe for nearly all feet. The heels of the shoe should not betoo high, should not be too short, and should be wide enough apart fromeach other to insure the wall of the foot obtaining a fair share of thebearing. Finally, even with the present method of shoeing, whenever it ispossible to allow the frog to come to the ground, it should be encouragedto do so, and excessive paring either of the latter organ or of the bars orthe sole should be strictly discountenanced. Where the sole is thin, or thefrog wasted, use a leather sole or a rubber pad. With these precautions, corns may be prevented from occuring even in a foot with a predisposingconformation. 

When corn is present, the first treatment usually adopted is that of'paring it out. ' This is advocated by Percival and by many other writers. We cannot say, however, that we agree with it--at any rate, not in the caseof simple dry corn. 

'Paring it out, ' and by that we mean thinning down the sole until close onthe sensitive structures, can only be advised in the case of suppuratingcorn, or in cases where doubt exists as to whether pus is present or not. In the latter case paring becomes necessary as an exploratory means todiagnosis. 

When it appears fairly certain, even in the case of a moist corn, that pusdoes not exist, then paring is to be discountenanced, for the reason thatit only tends to weakening of the parts and to assist largely in the corn'srecurrence. 

Those who advocate it do so for the reason that it relieves pressure on theinjured parts. 

That it does so directly from below cannot be denied; but that it alsofavours contraction and compression from side to side is equally certain. 

A moderate paring may, however, be indulged in, say, to about one-halfthe estimated thickness of the sole. Softening of the horn and consequentlessening of pressure may then be brought about by the use of oil, oil andglycerine, tincture of creasote, or by poulticing. 

In the case of a moist corn the paring should be stopped immediately thetrue nature of the injury has made itself apparent. Warm poultices or hotbaths should then be used in order to soften the surrounding parts, lessenthe pressure, and ease the pain. After a day or two day's poulticing, should pain still continue with any symptom of severity, the formationof pus may be expected, and it is then time for the paring to be carriedfurther, until the question 'pus or no pus?' is definitely settled. 

Should the moisture be due simply to the presence of the inflammatoryexudate, then poulticing alone will have the desired effect, and thepain will be lessened. With the decrease in pain the poulticing may bediscontinued, and the horn over the seat of the injury dressed with someantiseptic and hardening solution. Sulphate of zinc, a mixture of sulphateof zinc and lead acetate, sulphate of copper, or the mixture known asVillate's solution, [A] may either of them be used. Suitably shod, and witha leather sole for preference, the animal may then again be put to work. 

[Footnote A: The composition of the escharotic liquid bearing his name waspublished by M. Villate in 1829 as under:

 Subacetate of lead liquid . .. . .. . .. 128 grammes. Sulphate of zinc [=a=a] . .. . .. . .. 64 grammes. Sulphate of copper, [=a=a] . .. . .. . .. 64 grammes. Acetic acid . .. . .. . .. . .. 1/2 litre. 

Dissolve the salts in the acid, add little by little the subacetate oflead, and well shake the mixture. ]

When dealing with suppurating corn, then, a considerable paring away of thehorn of the sole becomes a matter of necessity. The freest possible exitshould be given to the pus, and this even when an opening has alreadyoccurred at the coronet. Unless this is done, and done promptly, theputrescent matter still contained within the hoof will make further inroadsupon the soft structures therein, and later upon the ligaments, and evenbone itself. 

Having given drainage to the lesion by the dependent orifice in the sole, poulticing should again be resorted to and maintained for at least threeor four days. The poulticing may then be discontinued, and the openings inthe sole injected with a weak solution of Tuson's spts. Hydrarg. Perchlor. , a 1 in 20 solution of carbolic acid, a solution of copper sulphate, withVillate's solution, or with any other combined antiseptic and astringent. The success of the treatment is soon seen in the cessation of pain and inthe decreased amount of discharge from the opening in the sole. 

Should pain unfortunately continue, the discharge remain, and a state offever reveal itself, then it may be understood that the suppurative processhas not been checked, that a portion of necrosed ligament, cartilage, or bone still remains, which, surrounded as it is by pus organisms andputrefactive germs, is sufficient to excite a constant irritation andmaintain the internal structures in a state of infection. In other words, we have what is known as a quittor. 

This will call for deeper operation. The horn of the wall must be removed, and the diseased structures, whether gangrenous keratogenous membrane, necrosed ligament, or carious bone, carefully excised or curetted. Thiswill be better understood by a reference to the chapter on Quittor, wherethe means for carrying out the necessary operative measures will be founddescribed in detail. 

_Surgical Shoeing for Corn_. --In the case of an ordinary dry corn, wherethe injury has been definitely ascertained to be accidental, no alterationin the shoeing will be necessary. Where, however, the corn is attended witha more than ordinary degree of inflammation, or where for some reason orother excessive paring has been practised, then it will become needfulto shoe with a special shoe. The object to be attained is the removal ofpressure from that portion of the wall next to the seat of corn. 

The most simple shoe for effecting this is the ordinary three-quarter shoe. The only way in which this differs from the ordinary shoe is that about aninch and a half of that branch of the shoe adjoining the corn is cut off(Fig. 102). If at the same time contraction of the heels exists, then, perhaps, a better shoe is that known as the three-quarter bar (Fig. 103). 

Or, if preferred, a complete bar shoe such as that described for sand-crackmay be used, and the upper portion of the web in contact with the foot atthe seat of corn thinned out so as to avoid pressure on the wall at thispoint. With this shoe we shall at the same time supply a certain amountof pressure to the frog, and aid in the healthy development of the partindirectly involved in the disease. 

The same pressure may also be given to the frog, and protection affordedthe sole, by the use of a leather sole, or rubber pad on leather, asdescribed when dealing with contracted feet. 

A further method of relieving pressure on this portion of the wall, withoutremoving the wall itself (a practice which should never be advised) is tomake certain alterations in the web of the shoe. This may be done in one oftwo ways. 

[Illustration: FIG. 102. --THREE-QUARTER SHOE. ]

[Illustration: FIG. 103. --THREE-QUARTER BAR SHOE. ]

In the first, that portion of the bearing surface of the heel of the shoeis 'dropped' about 1/8 inch from the plane of the remainder, so that theshoe at this position does not come into contact with the foot at all (seeFig. 104). 

In the second case the shoe is what is termed 'set' at the heel. Here it isthe plane of the _wearing_ surface of the shoe that is altered. The hinderportion of the required heel is thinned so that its lower surface does notcome into contact with the ground. By this means the wall is freed fromconcussion and pressure. At the same time the upper surface of the shoe isin contact with the wall of the foot (see Fig. 105). 

This 'setting' of the shoe is preferable to the method first described. Itaffords a greater protection to the foot, and does not allow of fragmentsof stone and flint getting in between the foot and the shoe, and so givingrise to further mischief. 

The 'set' portion should be fitted full and long. It is obvious, too, thatthe animal should not be allowed to carry the shoe too long; otherwise, asthe other portion of the shoe wears down to the level of the 'set' heel, pressure on the tender part of the foot will again result. 

[Illustration: FIG. 104. --SHOE WITH A 'DROPPED' HEEL. ]

[Illustration: FIG. 105. --SHOE WITH A 'SET' HEEL. ]

In applying surgical shoes for corn of long standing, it must be rememberedthat the protection so afforded must be continued for some time. It is notsufficient to see the lesion itself disappear. In addition to that thereis also, in the majority of cases, a certain amount of contraction to beovercome. This can only be done by continuing the use of a leather soleor some form of frog or bar-pad as recommended for the relief of thatcondition. 

C. CHRONIC BRUISED SOLE. 

A similar condition to that of corn may be met with in other positions onthe sole. It is described by Rogerson as sand-crack of the sole[A], and isinvariably met with around that portion of the sole in contact with theshoe. 

[Footnote A: _Veterinarian_, vol. Lxiii. , p. 51. ]

The animal is lame, and the shoe is removed in order to ascertain thecause. Nothing at first is noticeable except that the animal flinches whenpressure is applied to the spot with the pincers, or the sole is tappedwith the hammer. 

On removing the sole with the knife, however, a distinct black mark isdiscovered, which, when followed up by careful paring, is often found tohave pus at the bottom. 

In this case the injury has resulted, as we have already intimatedelsewhere, from causing the animal to wear for too long a time a shoe withtoo broad a web or insufficiently seated. Or it may have originated withthe irritation set up by foreign and hard substances between the web of theshoe and the foot. 

In his description of this condition Mr. Rogerson draws attention to thefact that the pus found should not be wrongly attributed to accidentalpricking of the foot. He says:

'Considering that the cracks or splits are always found in the immediatevicinity of the nail-holes, a certain amount of discretionary skill isrequired in order that the lameness may be attributed to its proper cause. This is an instance in which the presence of the veterinary surgeonis imperative, in order to prevent undue blame being attached to theshoeing-smith. Misconception in these cases might very easily arise whenparties concerned are disposed to accept an unskilled opinion, sometimesresulting in danger to the proprietor of the forge, not only of losing ashoeing contract, but also of being involved in other ways which wouldprobably prove even more disastrous. 

'Horses that stand on sawdust or moss litter are sometimes found withextensive discoloration of the horny sole in front of the frog. Theirbedding material collects in the shoe as snow does, and forms a mass, whichkeeps a continued and uneven pressure upon the sole. A sound foot is notinjuriously affected, but a very thin sole is, and so also is a sole whichhas been bruised by a picked up stone. Even a slight bruise becomes seriousif pressure is allowed to remain active over the injured part. Lamenessincreases, serous fluid is effused between the horn and sensitive part, oreven hæmorrhage may take place. '[A]

[Footnote A: Hunting, _Veterinary Record_, vol. Xiv. , p. 593. ]

_The Treatment of Chronic Bruised Sole_ offers no special difficulty. Removal of the cause (in nearly every case incorrect bearing of the shoe)is the first consideration. That done, the lesion may be searched for andtreated in the ordinary manner as described for corn. When pus is presentit must, of course, be given exit, and an antiseptic solution applied tothe wound. Should the sensitive structures be laid bare when allowing thepus to escape, then the wound so made should afterwards be protected with aleather sole and antiseptic stopping. 

CHAPTER VIII

WOUNDS OF THE KERATOGENOUS MEMBRANE

A. NAIL-BOUND--BIND OR TIGHT-NAILING. 

_Definition_. --By the term 'nail-bound' is indicated that accidentoccurring in the forge in which the nail of the shoe is driven too near thesensitive structures. Although involving no actual wound, it is importantto consider the condition under the heading of this chapter, in order thatit may be distinguished from the graver accident of a 'prick. '

_Causes_. --Very largely the whole matter of causation turns on the correctfitting of the shoe. The points especially to be noticed in this connectionare (1) the position of the nail-holes in the web of the shoe, (2) the'pitch' of the nail-holes. 

Regarding the position of the nails, it goes without saying that the firstconsideration when 'holing' the shoe should be to punch the holes oppositeto sound horn. This remark applies especially to shelly and brittle feet, the type of feet in which tight-nailing most often occurs. The nextconsideration in this connection is that of punching the holes so that thenail emerges from the upper surface of the web at exactly its correct pointof entrance on the bearing surface of the foot. This should be on the whiteline immediately where it joins the wall. From this position any markeddeviation inwards ('fine-nailing, ' as it is termed) is bound to give to thenail a direction dangerously near the sensitive structures. 

The 'pitch' of the nail-holes should be such that the nail is guided moreor less nearly to follow the line of inclination of the wall. Accordingly, the nail-holes at the toe should be 'pitched' distinctly inwards, theinward pitch lessening as the quarters are reached, until the hindermostnail-hole or two is pitched in a direction that is almost perpendicular. 

Too great an inward inclination of the nail will, however, give rise to abind. 

It is probable that 'tight-nailing' results more often from fine punchingof the shoe than from any fault in the pitch of the hole. Inattention toeither detail, however, is apt to bring the mischief about. 

Even with a correctly fitted shoe, and with a normal foot, tight-nailingmay occur as a result of sheer carelessness on the part of the smith. 

_Symptoms_. --Possibly the animal returns from the forge sound. It is onthe following day, as a rule, that evidence of the injury is given by theanimal coming out from the stable lame. In a well-marked case the footis warmer to the hand than its fellow, and percussion over the wall willsometimes reveal the particular nail that is the cause of the trouble. Should the shoe be removed, then the fact that the hole the nail has madeis far too close to the sole often points out at once the seat of themischief. 

_Treatment_. As to whether or not the shoe should be removed is very much amatter for careful discretion on the part of the veterinary surgeon. Wherethe foot is shelly and brittle even a good smith sometimes finds himselfunable to firmly attach the shoe without verging closely on causing thecondition we are now describing. The author has known cases where animalswith feet of this description have almost invariably returned from theforge, or rather been found the next day, with a suspicion of tenderness. After the lapse of a day or two this has quite often disappeared, andnothing in the meantime been done with the foot. Seeing, therefore, thatremoval and refitting of the shoe is in this case attended with risk ofbreaking away portions of the brittle horn, and so rendering the foot in aneven worse condition than it was before, it is policy to decline to havethe shoes removed unless worse symptoms make their appearance. 

In coming to this decision the veterinary surgeon must be guided by notingin the wall the points of exit of the nails. Should the nail adjoining theposition already pronounced to be tender have come out at a higher pointthan the others, it may be assumed that at a lower position in its coursethrough the horn it has gone near the sensitive structures without actuallypenetrating the horny box, and that in the course of a day or two thesensitive structures involved will accommodate themselves to the pressurethus inflicted. 

If, on the other hand, symptoms of tight-nailing show themselves in ananimal with good sound feet, then there is no objection to be raisedagainst having the shoe at once removed. Should the offending nail bedefinitely detected, then the shoe may again be put on, and that particularnail omitted from the set. 

B. PUNCTURED FOOT. 

(_Pricked Foot_--_Nail-tread_--_Gathered Nail_. )

_Definition_. --Under this heading we propose describing wounds of thefoot occurring in the sole or in the frog, and penetrating the sensitivestructures beneath. 

_Causes_. --These we shall consider under two headings:

1. Wounds resulting from the animal himself 'picking-up' or 'treading' onthe offending object. 

2. Cases of pricking in the forge. 

Those occurring under the first heading are, of course, purely accidental. In the majority of cases, the object picked up is a nail; but similarinjury may result from the animal treading on sharp pieces of wood oriron, on pieces of umbrella wire, on pointed pieces of bones, broken-offstable-fork points, sharp pieces of flint, etc. The same accident may alsooccur in the forge as a result of the animal treading on the stumps ofnails, from treading on an upturned shoe with the stumps of nails _insitu_, or from treading on an upturned toe-clip. It may also occur from anaccidental prick with the stable-fork when 'bedding up, ' or from castingpart of a shoe when on the road and treading on the nails, in this caseleft sometimes partly in and partly out of the horn. 

'Serious wounds of this description are also met with in animals engaged incarting timber from plantations in which brushwood has recently been cutdown. This is, of course, from treading on the stake-like points that areleft close to the ground. Hunters also meet with the same class of injurywhen passing through plantations or over hedge banks, where the hedge hasjust been laid low or cut down. 

'Agricultural horses also meet with severe wounds of this class fromtreading on an upturned harrow. '[A]

[Footnote A: _Journal of Comparative Pathology and Therapeutics_, vol. Iv. , p. 2. ]

It has been remarked how strange it is that nails should so readilypenetrate the comparatively hard covering of the foot. The matter, however, admits of explanation. One knows from common observation how easy it is totilt a nail with its point upwards by exerting a pressure in a more or lessslanting direction upon its head. This is exactly the form of pressure thatis no doubt put upon the nail if the animal treads upon it when moving atany pace out of a walk. The foot in its movement forward tilts the nailup, and almost simultaneously puts weight upon it. The great weight of theanimal is then quite sufficient to account for its ready penetration. 

In purely country districts cases of punctured foot are of far lessfrequent occurrence than in large towns. In the latter, animals labouringin yards where a quantity of packing is done, or engaged in cartingrefuse containing such objects as we have mentioned, or broken pieces ofearthenware or glass bottles, meet with it constantly. 

For the manner of causation of those wounds to the foot occurring inthe forge the reader may be referred to the matter under the heading of'nail-bound. ' As in that case so in this the nail may be wrongly directedby improper fitting of the shoe, by the 'pitch' of the hole, or by theposition of the hole. The nails may also be wrongly directed as a result offaulty pointing, or by meeting with the stump of a nail that has carelesslybeen allowed to remain in the substance of the horn. 

Often pricking is a result of carelessness engendered by a rush of work. Often it is almost unavoidable on account of the character of the foot thatis brought to be shod. Feet with thin horn, especially a thin sole, feetwith horn shelly and brittle, each in their way are difficult to shoe. 

Sometimes pricking is purely accidental, as in the case of a 'split' nail. The nail as it is driven splits at its point, and continues to split downits centre, one half emerging at the correct spot on the wall, the otherhalf bending inwards, and penetrating the sensitive structures. 

_Common Situations of the Wound_. --In a case of picked-up nail the commonseat of puncture is about the point of the frog, either in one of thelateral lacunæ, in the median lacuna, or the apex of the frog itself. Incomparison with this puncture of the sole is rare. 

Prick sustained at the hands of the smith may, of course, run in either ofthe following directions: (1) Directly into the position where the hornyand sensitive laminæ interleave; (2) between the sensitive laminæ and theos pedis; (3) into the os pedis itself; (4) the nail may bend excessivelyimmediately after entering the horn, and so pass either between the hornyand sensitive sole; or (5) between the sensitive sole and the bone. 

_Classification_. --Punctured wounds of the foot may be classified asfollows:

_Simple or superficial_ when penetrating no structure of great importance. For instance, a prick that penetrates to the sensitive sole and is notdriven with sufficient force to seriously injure the os pedis we may regardas simple. In the same manner a prick to the frog that, although deep, ismainly concerned with penetrating the plantar cushion may also be classedas simple. 

_Deep or penetrating_ when driven with sufficient force or in such adirection as to injure structures whose penetration is calculated to giverise either to serious constitutional disturbance or to permanent lameness. In this category we may place injuries to the terminal portion of theperforans, puncture of the navicular bursa, fracture of the navicular boneand penetration of the pedal articulation, and splintering of the os pedis. 

_Symptoms and Diagnosis_. --While discussing the symptoms and diagnosis, wewill still continue to consider our subject under the two headings of (1)accidental 'gathering' of some foreign body, and (2) pricks inflicted inthe forge. 

In a few cases belonging to the former class the veterinary surgeon isfortunate in obtaining a direct history of the injury. The driver has seenthe animal go suddenly lame, and has examined the foot for the cause. Either the nail has been found embedded in the horn, or the puncture it hasmade detected, and the matter has been reported. The foot is then exploredand the full extent of the injury ascertained. 

In many cases, however, it so happens that no evidence of the infliction ofthe injury is forthcoming. The momentary lameness occurring at the time ofthe prick is unreported at the time by the attendant, and the horse fora time goes sound. It is not until the changes set up by the subsequentinflammatory phenomena make their appearance, and lameness results, thatattention is called to the foot. When this happens there has, as a rule, been time for pus to form around the seat of puncture--a matter of aboutforty-eight hours. 

The horse is now brought out for the veterinary surgeon's examination, going distinctly lame. If the case is well marked there may then be notedby the man of experience many little signs pointing to the foot as the seatof the lameness. These, though well enough known to the practitioner, arenevertheless difficult to describe. It is, in fact, hard to say exactly inwhat they really consist, appearing to be as much a matter of intuition asof actual observation. 

There is a peculiar 'feeling' characteristic in the gait. The affected footis put forward fearlessly enough, but is not nearly so rapidly put to theground. When at rest the foot is almost immediately pointed, and the painat intervals manifested by pawing movements. It is this extreme liberty ofthe rest of the limb, as evinced during the pawing movements, that reallystrikes one. Shoulder, elbow, knee, and fetlock are all easily andpainlessly flexed and extended. There is nothing wrong with them; it mustbe the foot. The short manipulation necessary to test the lameness--viz. , the walk and slow trot--is sufficient to raise the animal's pulse andquicken the breathing. 

All this is enough, and more than enough, to lead the veterinary surgeonto examine the foot. It is hot to the touch, and at the coronet tender topressure, possibly in a neglected case fluctuating at the heel. Pain isevinced by the animal withdrawing his foot when percussion takes place overthe affected spot. In a bad case one gentle tap is all that is needed. Theanimal at once snatches away his foot, holds it high from the ground, andmakes pawing movements in the air. At that moment, too, his countenance ishighly expressive of the pain he is suffering. Again the foot is explored, the injury found, and the pus liberated. 

Regarding the manner of exploration of the foot we will take first thatcase in which the veterinary surgeon is called in early, and in which pushas not yet had time to form. Sometimes the merest cleaning up of theinferior surface of the foot then reveals a distinct stab either in thesole or the frog. 

If the accident be recent only a little blood will be found, either liquid, or coagulated about the wound. Later there exudes from the stab a flow ofyellow, serous fluid. The opening thus found should be carefully probed, and its depth and situation noted. 

At other times the prick is not so readily apparent. The nail or otherobject has penetrated and afterwards withdrawn itself. The naturalelasticity of the horn, especially that of the frog, causes it to contractupon the puncture, and to largely obliterate the hole made. What, therefore, may look to be but a simple injury to the horn alone mayin reality be the only evidence of a stab complicating the sensitivestructures. It thus behoves the veterinary surgeon to follow up andcarefully cut out any unnatural-looking mark in the horn, more especiallyif the horn is discoloured, or if blood is extravasated into its fibres, orthere is moisture exuding from the part. 

In some cases of this description the knife in the act of paring comes intocontact with the cause of the trouble. Sometimes this is a nail, sometimesa sharp and small piece of flint, so deeply penetrated as to have becomequite buried. When met with in this manner, however, the foreign body ismore often than not a splinter of wood deeply embedded in the cleft of thefrog or in the frog itself. 

The fact that multiple punctures may occur should here be remembered, andthe remainder of the inferior surface of the foot thinly pared. 

On withdrawal of the foreign object blood may immediately follow. Shouldthe former have been fixed in position for some time, however, pus isnearly always found at the bottom of the wound. As a rule, its removal iscomparatively easy, but one case recalls itself to the author's mind inwhich the extraction was a matter of considerable difficulty. The offendingobject was a large, flat-headed nail, some 2 inches long. This was drivenfast into the os pedis, and necessitated the employment of a pair ofpincers and the exertion of some amount of force to move it from itsposition. 

In this connection it must be remembered that the penetrating objectsometimes breaks off after entering the foot. The fact that thisoccasionally happens only serves to give point to the advice we havepreviously rendered--that every stab should be carefully probed, and itsexact condition and depth ascertained. 

In those cases where percussion has led to the positive opinion that pusreally exists, then the exploration must be most searching. There may, ormay not, be a suspicious-looking mark to work on. In the latter case, theveterinary surgeon must not be content with confining his paring operationsto one spot. The sole should be carefully thinned all round, and thethinning cautiously proceeded with until either small, pin-pointhæmorrhages denote that healthy sensitive structures have been reached, ora sudden flow of pus indicates that the injury has been definitely located. 

While the symptoms remain much about the same, the diagnosis of pricksreceived in the forge, as compared with those occurring in the naturalmanner, is easy. The animal starts to the forge quite sound, and returns, perhaps, with a slight limp. The slight limp in two days' time becomes adecided lameness, and no doubt remains as to what has occurred. The merefact of the lameness arising immediately after a visit to the forge shouldbe sufficient in the majority of cases to lead one to a correct diagnosis. 

Where the opinion has been formed that a prick has been received, then theshoe should be removed. 

This operation should always be superintended by the veterinary surgeonhimself. After the removal of the clinches, the nails should be drawn oneat a time with the pincers, and carefully examined. Often the offendingnail may thus be picked out by observing upon it blood-stains, or themoisture from inflammatory exudate or from pus. Further inflammation willalso be gathered by occasionally meeting with a nail that has split. 

At this stage, too, the veterinary surgeon should have noticed whether ornot the smith has previously sent the animal home with what is known as a'draw back. ' He has discovered, immediately after he has done it, that hehas pricked the animal. He has then withdrawn the nail, and either sent theanimal back with that nail altogether missing from the set in the shoe, orwith the hole filled up with a stump. 

The shoe once off, the holes made by the nails in the horn should beminutely examined for the presence of hæmorrhage, inflammatory fluid, orpus exuding from them, and also for evidence of their correct placing inthe foot. Should fluid matter issue from any one of them, or should it bedeemed that one has approached too near the inner margin of the whiteline, more especially if tenderness exists around it, that hole should befollowed up with a 'searcher' or small drawing-knife until diagnosis iscertain. 

_Complications_. --Before proceeding to discuss the complications that mayarise in the case of pricked foot, we may call to mind that the anatomy ofthe parts teaches us that the most serious position in which a puncturedwound can occur is at the centre of the foot. Here the plantar aponeurosis, the navicular bursa, the navicular bone itself, or the pedal articulationmay be injured. 

Anterior to this position the most serious mischief that can ordinarilyresult is stabbing of the os pedis. 

Posterior to the position we have named, the only structure to be injuredis the plantar cushion. 

Anatomically, then, the inferior surface of the foot may be divided intothree zones, as follows:

_A. Anterior_, extending from the toe to the point of the frog. 

_B. Middle_, extending from the point of the frog to the commencement ofits median lacuna. 

_C. Posterior_, including everything posterior to the middle zone. 

This division of the inferior surface of the foot into zones will besomewhat of a guide also when describing the complications next to follow:

_(a) Suppuration_. --This is the common complication of most wounds of thefoot. When detected, it calls for immediate surgical interference in theshape of removal of the horn of the sole or the frog, as the case may be. This we shall consider further under the treatment. 

_(b) Separation of the Horny Frog_. --This is a sequel to pus formation inthe sensitive structures immediately beneath it, and the condition makesitself apparent by a line of separation between the horn and the skin ofthe heel of the injured side. 

_(c) Wounding of the Plantar Aponeurosis_. --This occurs when amoderately-deep penetration of the horn of the middle zone has taken place. It is always most painful, especially when complicated by necrosis. Theheel is then persistently elevated, and lameness is extreme, in some casesso severe as to cause the leg to be carried altogether. 

In favourable cases the necrosed piece of tendon is sloughed off by theprocess of suppuration, and escapes with the discharges from the wound. There is then an abatement in the symptoms, and recovery is rapid. 

Commonly, however, on account of the non-vascularity of the structure ofthe tendon, the necrotic spot in it tends to spread. The wound is thus ledto become fistulous in character, and the pus forming within it preventedfrom escaping from the original opening. As a result, lameness and feverpersist. There is a gradual increase in the severity of the symptoms, andlater fistulous openings appear in the hollow of the heel. 

_(d) Puncture of the Navicular Bursa_. --This results from a prick inexactly the same position as that last described, and means that thepenetrating object has gone deeper, It may be distinguished from punctureof the plantar aponeurosis alone by the fact that there is an excessivedischarge of synovia from the wound. This, as it escapes, is at first clearand straw-coloured. Later it becomes cloudy and flaked with pus, and showsa tendency to coagulate in yellowish clots. 

Pain and accompanying fever is most marked, much more so than when theplantar aponeurosis alone is injured. 

Should the original wound be insufficiently enlarged, or should its openingbecome occluded by the solid matters of the discharge, then this condition, like the last, ends in the formation of fistulous openings in the heel. These make their appearance as hot, painful, and fluctuating swellings inthat position. Later they break, discharge their contents, and leave afistulous track behind. 

_(e) Fracture of the Navicular Bone_. --Penetration of the substance ofthe navicular bone, _without_ its fracture, adds nothing to the symptoms wehave described under puncture of the bursa. That the bone has been reachedby the penetrating object may be detected by probing. This, however, must be performed with care, especially if a flow of synovia is absent. Otherwise, the wound, as yet, perhaps, superficial enough to avoidpenetrating even the bursa, is made a penetrating one by the probe itself. 

Fracture of the navicular bone is fortunately rare. 

_(f) Penetration of the Pedal Articulation and Arthritis_. --This we shallconsider in greater detail in Chapter XII. It is sufficient here to statethat the condition may be suspected when a hot and painful swelling of thewhole coronet makes its appearance. There is at the same time a diffusedoedema of the fetlock and the region of the cannon, sometimes extendingupwards to the whole of the limb. 

Of all the complications to be met with in punctured foot this is the onemost to be dreaded. The intense pain and the high fever render the animalweak and thin in the extreme. The appetite becomes impaired, sometimesaltogether lost, and the patient in many cases appears to die from sheerexhaustion. Added to this is always the extreme probability of the woundbecoming purulent, and later the dread of general septic infection of theblood-stream ensuing, and death resulting from that. Even with the happierending of resolution, anchylosis of the joint and incurable lameness ismore often than not left behind. (See Suppurative or Purulent Arthritis, Chapter XII. )

_(g) Ostitis and Caries of the Os Pedis_. --Injuries to the os pedis aremet with in the anterior zone of the foot. Evidence that the bone has beeninjured is not usually forthcoming until after the lapse of some days. One is led to suspect it by the fact that there is no indication of thesuppurative process extending further upwards, coupled with the facts thatgreat pain, high fever, and extreme lameness persist, and that there is acontinuous discharge from the wound of a copious blood-stained and foetidpus. Used now, the probe reveals the fact that the bone is bared, andconveys to the hand that is holding it a sensation of crumbling fragility. 

_(h) Wounding of the Lateral Cartilage and Quittor_. --This occurs as theresult of a deep stab in the posterior zone. Ordinarily, wounds in thisposition are unattended with serious consequences, and the prick has to bea deep and a severe one before the cartilage is reached. What then happensis that a spot of necrosis is formed round the seat of puncture in thecartilage. This, unless met with surgical interference, is sufficientto maintain the wound in a septic condition; it takes on a fistulouscharacter, and a quittor is formed. (See Chapter X. )

_(i) Septic Infection of the Limb_. --This we have already once or twicereferred to. It simply means that the septic matters from the wound havegained the lymphatics, and finally the blood-vessels of the limb, and setup local lesions elsewhere than in the foot. Although dismissed here withthese few words, the condition is a most serious one. Usually, it hasresulted from penetration of the pedal articulation and septic infection ofthe joint. In the vast majority of these cases slaughter is both humane andeconomical. 

_Prognosis_. --The first consideration in giving a prognosis in puncturedfoot should be the position of the wound. When occurring in the middlezone, the surgeon's statements should be most guarded, and the dangersattending a wound in that particular position fully explained to the owner. A wound in the anterior position is, as we have said, far less serious, andone in the posterior region of the foot even less serious still. 

Whenever possible, the nail or other object causing the prick should beexamined. Much of the prognosis may be based upon the estimated depth ofthe wound, and this, in many cases, it is far safer to calculate from thelength of the offending body than from the use of the probe. We need hardlysay that in the middle zone the deeper the prick, the more serious thecase, and the less favourable the prognosis. As in succession the sensitivesole, the plantar aponeurosis, the navicular bursa, the navicular bone, orthe pedal articulation is injured, so with each step deeper of the prick isthe severity of the case increased. 

The shape of the penetrating object may also be considered. One excessivelyblunt, and calculated to bruise and crush the tissues, will inflict a moreserious wound than one of equal length that is pointed and sharp. 

The conformation of the foot should also be regarded. Wounds in well-shapedfeet are less serious than in feet with soles that are flat or convex, orin which the horn is pumiced or otherwise deteriorated in quality. 

Although unaffecting the prognosis so far as the actual termination of thecase is concerned, it may be mentioned that punctured foot is far moreserious in a nag than in a heavy draught animal. With an equal degree oflameness resulting in each case, the former will be well-nigh useless, butthe latter still capable of performing much of his usual labour. 

The temperament and condition of the patient will also in many caseslargely influence the prognosis. An animal of excitable and nervousdisposition is far more likely to succumb to the effects of pain andexhaustion than the horse of a more lymphatic type. In the case of apatient suffering from a prick to a hind-foot while heavily pregnant, theattempted forecast of the termination should be cautious. More especiallydoes this apply to the case of a heavy cart-mare. Ordinarily, theheavier the breed, the greater the tendency to lymphatic swelling of thehind-limbs. With pregnancy this tendency is enormously increased, and it isno uncommon thing to find a cart-mare in this condition, with legs, as theowner terms it, 'as thick as gate-posts. ' A prick to the foot, with thelymphatics of the limb in this state, is extremely likely to end in septicinfection of the leg, for there appears to be no doubt but that invasion ofthe lymphatics with septic matter is favoured by a sluggish stream. Also, in the case of a patient in the advanced stages of pregnancy, it must beremembered that, no matter how great may be the need, one is debarred, forobvious reasons, from using the slings. 

_Treatment_. --_In a simple_ case--and by 'simple' here we mean the casein which the injury is discovered early, and pus has not yet commenced toform--our first duties are to give the wound free drainage, and to maintainit in an aseptic condition. The first of these objects is to be arrived atby paring down the horn in a funnel-shaped fashion over the seat of theprick. It is, perhaps, even better to thin the horn down to the sensitivestructures for some little distance round the injury. By this latter methodpressure from inflammatory exudate is lessened, and the after-formation ofpus, if unfortunate enough to occur, the more readily detected, and theless likely to spread upwards. The matter of asepsis may then be attendedto. 

When the puncture is sufficiently large to admit of it, the antisepticdressing is best applied by means of the probe. This instrument is thinlywrapped with tow, or other absorbent material, so as to form a small swab. Dipped in a suitable solution (as, for example, Zinc Chloride, Spts. Hydrarg. Perchlor. , Carbolic Acid, or any other that suggests itself), theswab is inserted into the prick, and the wound conveniently mopped clean. A further portion of the medicated tow is then pushed partially into thewound, and allowed to remain in position. The foot is subsequently wrappedin a clean bag, and kept free from dirt. This dressing should be repeatedtwice daily. 

If the prick is in a dangerous position, and deep enough to occasion alarm, our precautions to prevent the formation of septic matters within it may bemore elaborate. The thinning of the horn and the swabbing of the woundmay, as before, be proceeded with. In addition, the whole foot may then beimmersed for some hours daily in a cold bath, which bath should be stronglyimpregnated with one or other of the following salts: Iron Sulphate, ZincSulphate, Copper Sulphate, Aluminium Sulphate, Lead Acetate, or SodiumChloride--better still, a mixture of the various sulphates here mentioned. If preferred, one of the more commonly accepted antiseptics--such asCarbolic Acid, Lysol, Boracic Acid, or Perchloride of Mercury--may besubstituted. 

By the cold of the bath inflammatory phenomena are held in check, while itsadded antiseptic prevents the formation of septic discharges. The lamenessgradually diminishes, and resolution is rapid. In this way deep andserious, wounds are sometimes easily and successfully treated. 

_When suppuration has occurred_--and this, by-the-by, is by far the mostfrequent condition in which we find punctured foot--treatment must beprompt and decided. Careful search must at once be made by thinning downthe sole, and carefully trimming the frog. On no account should theveterinary attendant rest content with 'digging' in one place, and uponthat basing a negative opinion as to the existence of pus. The paringshould be carried on, until either pus or hæmorrhage shows itself, in atleast three positions--namely, at the most anterior portion of the sole, and in the sole at each side of the frog. In addition to this, the frogitself should be minutely examined for evidence of puncture, or for leakingof pus at the spot where the horn of the heels joins the skin. 

In many of our cases, however, this careful search is not so necessary. The accompanying symptoms are so decided as to leave no doubt as to thecondition of the case. In such instances paring may often be commenced overthe exact position of suppuration as previously ascertained by percussion. 

When met with, the track formed by the suppurative process should befollowed up in whichever direction it has spread. This will oftennecessitate the removal of the greater part, if not the whole, of the hornysole. 

Having given vent to the pus, and opened up the cavity made by itsformation, the foot should be placed in a hot poultice or, preferably, in ahot antiseptic bath. [A]

[Footnote A: At the time of writing this, a certain amount of discussion isgoing on in our veterinary journals as to whether a hot or a cold bath isthe one indicated. It is urged against the application of heat that itfavours organismal growth and reproduction, and tends rather to induce thespread of the suppurative process than to overcome it. Those who hold thisopinion urge in support of it that cold applications are inimical to thelife of the pus organism. At the same time, it must be remembered that injust so far as cold inhibits the growth of the invading germ, so in justthe same degree does it adversely influence the functions of the tissuesthat are to fight against it. To our minds the question thus set up mustalways remain more or less a moot-point, and while we fully agree that coldundoubtedly checks the growth of septic material, we just as fully believethat warmth serves to place the healthy surrounding structures in a farbetter condition to maintain a vigorous phagocytosis against it. Wethus continue to advise a hot antiseptic poultice, or, better still, abath. --THE AUTHOR. ]

At the end of the third or fourth day the poultice or the bath may bediscontinued, and the opening in the sole dressed with any suitableastringent and antiseptic. 

The most serious complication arising from this method of treatment isone of excessive granulation of the sensitive sole. This we find to besuccessfully held in check by a daily application of undiluted Spts. Hydrarg. Perchlor. (Tuson). Should the granulations become very exuberant, then the knife must be called to our aid, and the wound so made afterwardsdressed with an astringent. 

When the suppuration has under-run the horny frog there should be nohesitation in at once removing all the horn that is visibly separated fromthe sensitive structures beneath. 

_When the os pedis is splintered and carious_, a portion of the sole roundthe wound is removed, and the bone exposed. The diseased portion is scrapedaway either with a curette or with the point of the drawing-knife. In thiscase the only after-treatment called for is the application of suitableantiseptic dressings. 

_When necrosis of the plantar aponeurosis has occurred_. We have alreadypointed out the tendency there is in this case for the wound to maintain afistulous character, and lead to the formation of abscesses in the hollowof the heel. With a wound in this position, as with a wound in any other, the only method of avoiding this termination consists in removing all thatis visibly diseased, whether it be soft structures, bone, ligament, ortendon, and giving the wound free drainage. 

This can only be done by removing the horny sole and frog, and cuttingboldly down upon the structures beneath. The operation is known asresection of the plantar aponeurosis, or the complete operation forgathered nail. 

Practised for some years on the Continent, this operation, on account ofits gravity, has been avoided by English veterinarians. From reportedcases, however, it appears often to be followed by success. 

That there is a large element of risk in the operation is quite evident, ifonly from the two facts mentioned beneath:

1. That the close attachment of the plantar aponeurosis to the navicularbursa, and the nearness of both to the pedal articulation, renderpenetration of a synovial sac or a joint cavity extremely likely. 

2. That there is always great difficulty in maintaining strict asepsis ofthe foot, more especially if it is a hind one. 

On the other hand, it may be argued that equal risk to the patient is runin allowing him to remain with a disease (and that disease a progressiveone) of the structures so closely antiguous to the navicular bursa and thepedal articulation. 

If only for that reason we give the operation brief mention here. 

The animal is prepared in the usual way for the operating bed; the footsoaked for a day or two previously in a strong antiseptic solution, thepatient cast and chloroformed, and the operation proceeded with. 

[Illustration: FIG. 106. --'CURETTE, ' OR VOLKMANN'S SPOON. ]

An Esmarch's bandage should be first applied, and a tourniquet afterwardsplaced higher up on the limb. The foot is then secured as described in anearlier chapter, and the whole of the horny structures of the lower surfaceof the foot (the sole, the frog, and the bars) pared until quite near thesensitive structures, or, if under-run with pus, stripped off entirely. Anincision is then made in each lateral lacuna of the frog, the two meetingat the frog's point. Each incision thus made should be carried deep enoughto cut through the substance of the plantar cushion. A tape is then passedthrough the point of the frog, tied in a loop, and given to an assistant todraw backwards. The plantar cushion itself is then incised in a directionfrom before backwards, and pulled on by the assistant, so as to expose theplantar aponeurosis. 

Should this be found at all necrotic, it may be taken that purulentinflammation of the navicular bursa and of the navicular bone itselfexists. The operator must then proceed to resection of the tendon in orderto treat the deeper structures thus affected. At its point of insertioninto the semilunar crest the tendon is severed and afterwards reflected. This exposes the inferior face of the navicular bone. Instead of theglistening and clear appearance it ordinarily presents, its glenoidcartilage is found to be showing hæmorrhagic or even purulent spots ofnecrosis. The terminal portion of the tendon must then be excised. 

To effect this a clean transverse incision is made at the extreme upperborder of the navicular bone. Here we are in close contact with the pedalarticulation, and great care is necessary in making this last incision, inorder that the synovial sac may not be penetrated. 

All structures showing spots of necrosis should now be carefully removed, either with the knife or with the curette. The knives most suitable for thelast stages of this operation are those depicted in Fig. 45 (_c_, _d_, and_e_). The curette, or Volkmann's spoon, we show in Fig. 106. 

[Illustration: FIG. 107. --RESECTION OF TERMINAL PORTION OF THE PERFORANS. The horny sole and the horny frog stripped from off the sensitivestructures. _a_, The plantar cushion; _b, b_, the plantar aponeurosis, orterminal portion of perforans; _c_, the navicular bone; _d_, interosseousligaments of the pedal articulation; _e, e_, semilunar crest of the ospedis; _f_, inferior surface of os pedis; _g, g_, the sensitive laminæ ofthe bars; _h, h_, bearing surface of the wall; _i, i_, the sensitive sole;_k_, the sensitive frog. ]

When at all diseased the glenoidal surface of the navicular bone should becuretted, even to the extent of the removal of the whole of the cartilage. A healthy, granulating surface is thus insured. 

The above figure from Gutenacker's 'Hufkrankheiten' explains shortly theposition of the operation wound and the structures involved, renderingfurther description unnecessary here. 

The operation ended, the dressing follows. Upon this depends very largelythe ultimate recovery of the patient, for it is only by careful attentionand suitable dressings that effectual repair of the injured structures maybe brought about. 

A light shoe is first tacked on to the foot, and those portions of thehorny sole that have been allowed to remain dressed with Venice turpentine, tar, or other thickly-adherent antiseptic. 

The exposed soft tissues are then dressed with pledgets of tow[A] soakedin alcohol and carbolic acid. This dressing must be allowed to remain inposition, and is kept there by means of a bandage, or the shoe with plates(Fig. 55) and a bandage over it. No pressure is needed; consequently, thepledgets of tow must not be too thick. 

[Footnote A: When using tow in the form of a pad, it is well to rememberthat many small balls of the material rolled lightly in the palm of thehand and afterwards massed together are far better than one large pad ofthe tow taken without this preparation. The irregularities of the wound arebetter fitted, and the whole dressing easier remains _in situ_ (H. C. R. ). ]

In the after-dressing of the wound careful attention must be paid to thegranulating surface. Where tending to become too vigorous in growth itshould be held in check by suitable caustic dressings. At the same time itmust be remembered that the granulating process of repair is always morerapid upon the plantar cushion and fleshy sole than upon the bone, or upontendinous or cartilaginous structures. As a result of this we have a woundshowing various aspects of cicatrization. Healthy granulation may beprofuse in one spot, while in another it may be checked either by a flowof synovia from the still open bursa, or by fragments of bone or of tendonstill acting as foreign bodies in the wound. These latter may be readilydetected by their standing out as dark and uncovered spots in the healthygranulation around, and should be at once removed. 

The time that an operation wound of this description takes to heal--andthat without complication--is from one to two or three months. Continuationof pain and intensity of lameness are not to be taken as indications offailure. The reparative inflammation in the synovial membrane is quitesufficient to induce pain severe enough to prevent the animal from placinghis foot to the ground for some weeks, even though the progress of thecase, all unknown, may be all that is desired. So long as a great amount ofpain is absent, and so long as appetite remains and swellings in the hollowof the heel fail to make their appearance, so long may the progress of thecase be deemed satisfactory. 

_Recorded Case of the Treatment_. --A cart-horse, aged six years, was sentto the Alfort School by a veterinary surgeon for having picked up a nailin the hind-foot. Professor Cadiot, judging the necessity for the completeoperation, performed it on January 14, and spared the plantar cushionas much as possible. In consequence of the plantar aponeurosis beingextensively necrosed, it was advisable to scrape the navicular bone anda part of the semilunar crest. The wound having been washed with a 1 percent. Solution of perchloride of mercury, it was dusted with iodoformand packed with gauze, and covered with a cotton-wool dressing, kept inposition by means of a suitable shoe. 

On January 16 there was no snatching up of the limb when the horse was madeto put weight upon it; he ate his food well, and his condition improvedevery day. On January 21 the dressing was removed; the wound appeared pinkyand granular, and there was no suppuration. The clot remaining from thehæmorrhage after the operation was removed, the wound was irrigated with ahot solution of sublimate, and then dusted with iodoform and covered with adressing of iodoform gauze and absorbent wool. At this date the horse couldstand on the injured limb. On January 31 a second dressing was made, andthe animal almost walked sound. On February 7 the wound had almost closedup, save in its central part, where there was a small cavity, and thelameness had disappeared. On February 15 the wound had completely healed, and its borders were covered by a layer of thin horn. As the animal wassound it was sent to work. 

The author directs attention to the rapidity with which a large andcomplete wound cicatrizes after the operation for gathered nail. [A]

[Footnote A: _Veterinary Record_, vol. XV. , p. 226 (Jourdan). ]

_In the case of Penetrated Navicular Bursa_, unaccompanied by the formationof any large quantity of pus, and uncomplicated by necrosis of theaponeurosis, our aim must be to maintain the wound in that happy condition. This is doubtless best done by keeping the foot continually in a cold bath, rendered strongly antiseptic by the addition of sulphate of copper andperchloride of mercury. Should there be intervals when the bath must beneglected, the foot in the meantime must be kept clean by antisepticpacking and bandaging, and a clean bag over all. This treatment should becontinued so long as the character of the discharge denotes that synovia isrunning. If, in spite of our precautions, the discharge becomes purulent, then the track made by the penetrating object should be syringed twicedaily with a 1 in 1, 000 solution of perchloride of mercury. 

During the treatment it will be wise to shoe the animal with a high-heeledshoe. We do not know as yet the full extent of the injury. The navicularbone may be tending to caries; or necrosis of the plantar aponeurosis, allunknown, gradually becoming pronounced. This calls for a relief of tensionon the perforans, and is only to be brought about by the high-heeled shoe. 

The result of the inflammatory changes in the tendon, aided possibly bythe use of the high-heeled shoe, is to afterwards bring about contraction. Where this has occurred, and the animal walks continuously on his toe, theshoe with the projecting toe-piece (Fig. 84) must be applied. When thecontinual use of the toe-piece appears inadvisable, the shoe devised byColonel Nunn may be used in its stead (see Fig. 108). 

The toe-piece is screwed into the toe of the shoe when the horse is aboutto be exercised, and forms a powerful point of leverage with which tostretch the contracted tendon, and the shoe, being thin at the heels, admits of this. The advantage of this form of toe-piece over the ordinaryform of fixed toe-lever is that it can be removed when the horse is in thestable; while the curved point diminishes the danger of the horse hurtingitself--a danger always present if it is on a hind-foot. (See alsoTreatment of Purulent Arthritis in Chapter XII. )

[Illustration: FIG. 108. --COLONEL NUNN'S SHOE WITH DETACHABLE TOEEXTENSION. ]

_Should a Sinuous Wound remain in the region of the Lateral Cartilage_, it should be explored, and its depth and likely number of branchesascertained. Should this exploration denote that the cartilage itself isdiseased, or that the wound is not able to be sufficiently drained fromthe sole, then we know that we have on our hands a case of quittor. Thetreatment necessary in such a case will be found described in Chapter X. 

_When the Complication of Purulent Arthritis has arisen_, the surgeon hasto admit to himself, reluctantly no doubt, that the case is often beyondhope of aid from him. Nothing can be done save to order continuousantiseptic baths and antiseptic irrigation of the wounds with a quittorsyringe, and to attend to the general health and condition of the patient. At the best it is but a sorry look-out both for the veterinary attendantand the owner of the animal. Even with resolution incurable lamenessresults, and the animal is afterwards more or less a walking exhibition ofthe limitations of surgery, while the owner, unless the animal is valuablefor the purpose of breeding, finds himself encumbered with a life that ispractically useless. (See Treatment of Purulent Arthritis, Chapter XII. )

_In the case of Lameness Persisting after the healing of all appreciablelesions_, then neurectomy is followed by good results. The animal, apparently recovered, is for a long time useless. Lameness persists forseveral months, as if the nail had at the moment of its penetration causedlesions, which doubtless it sometimes does, similar to those of naviculardisease. Examination of the foot in this case reveals no lesion, and thepain has evidently a deep origin. The lameness caused by it is subject tovariation. Frequently it becomes lessened during rest, and increased byhard work, while sometimes it is very much more pronounced at starting thanafter exercise. 

It is here that neurectomy is called for. The operation does nothing toimpede the work of healing going on, and allows free movement of the footand pastern to take place. At the same time suffering and emaciation cease, and the animal is rendered workable. [A]

[Footnote A: _Veterinary Record_, vol. Ii. , p. 371. ]

C. CORONITIS (SIMPLE). 

TREAD, OVERREACH, ETC. 

1. _Acute_. 

_Definition_. --Under the heading of simple coronitis in its acute form weintend to describe those inflammatory conditions of the skin and underlyingstructures of the coronet occurring without specific cause. Specificcoronitis will be found described in Chapter IX. 

_Causes_. --This condition is almost invariably set up by an injury--eithera bruise or an actual wound--to the coronet. By far the most common amongsuch injuries are those inflicted by the animal himself by means of theshoes. 

That known as 'tread' is caused by the shoe on the opposite foot, and mayhappen in a variety of ways. More often than not it is met with in the feetof heavy draught animals, and is there caused by the calkin, either whenbeing violently backed or suddenly turned round. It may also occur inhorses with itchy legs, as a result of the animal rubbing the leg with theshoe of the opposite limb. The irritation in this case is nearly alwaysdue to parasitic infection (_Symbiotes equi_), and becomes sometimes sounbearable as to render the animal unmindful of the injury he may beinflicting so long as he experiences the relief obtained by the rubbing. 

Self-inflicted tread is also sometimes met with when horses are workedabreast at plough. The animal in the furrow, with one foot sometimes in andsometimes out of the hollow, is caused to make a false step, and so bringsthe injury about. 

Animals worked in pairs are further liable to receive a tread from the footof their companion. This is commonly seen in heavy animals at agriculturallabour in fields, where the walking is uneven, and abrupt turning constant. It is not uncommon either in animals at work in vans in town, and isoccasionally met with in the feet of carriage-horses. 

'Overreach' is the term used to indicate the injury inflicted on thecoronary portion of the heel of the fore-foot by the shoe of the hind. Ordinarily, overreach occurs when the animal is at a gallop, and is thusmet with in its severest form in hunters and steeplechasers. It can onlyoccur when the fore-foot is raised from the ground and the hind-foot of thesame side reached right forward. When the feet separate the injury takesplace. In its movement backwards the inner border of the shoe of thehind-foot catches the coronet of the fore, and tears it backwards with it. Quite frequently a portion of the skin is removed entirely, but often ithangs as a triangular flap. The flap in such a case is always attached byits hindermost edge, and indicates plainly enough that the direction of theblow that cut it must have been from before backwards. 

Although ordinarily inflicted at the gallop, the same injury may, nevertheless, be caused by allowing a fast trotter, and one with extremefreedom of action behind, to push forward at the utmost limit of his pace. The outside heel is the one most subject to the injury. 

While the common form of injury to the coronet is, as we have described, that occasioned by the animal's own shoe, or that of a companion, it isevident that the foot is also open to similar injuries from quite outsidesources. Falls of the shafts when unyoking animals from a heavy cart, blowsor wounds from the stable fork, wounds resulting from the foot becomingfixed in a gate or a fence, either may equally well set up the mischief. 

Apart from severe injury, a particularly troublesome form of coronitis mayarise from the condition of the roads. We refer to the conditions attendanton a thaw after snow. The animal is called upon to labour in, or perhapsstand for long periods in, a mixture of snow and water, or snow and mud. That this must have a prejudicial effect upon the structure of the coronetis plain. The circulation of the part, already predisposed to sluggishnessby reason of its distance from the heart, is farther impeded by theaction of the cold. Small abrasions of the skin, so small as to scarcebe noticeable, are in this case freely open to infection with the septicmatter the mud contains. Necrosis and consequent sloughing of the skinis bound to follow, and an extensive ulcerous wound, or a spreadingsuppuration of the coronary cushion is the result. 

_Symptoms_. --We will take first the case in which no actual wound isobservable. Here the first indication of the trouble is the appearanceof an inflammatory swelling, confined usually to one side, but extendingsometimes to the whole of the coronet. Always the part is hot and tender, and with it the patient is lame--so much so, in many cases, as to be unableto put the foot to the ground, the toe alone being used. 

In a mild case, uncomplicated by septic infection, these symptoms rapidlysubside, and resolution occurs. 

Always, however, the presence of septic infection must be suspected andlooked for. When this has occurred, the inflammatory swelling becomeslarger and more diffuse, and the animal fevered. This is then followed bya slough of the injured part. A portion of the skin first becomes gray, oreven black, in appearance, and around it oozes an inflammatory exudate, oreven pus. The skin immediately adjoining the spot of necrosis is swollenand hyperaæmic, and extremely painful and sensitive. Later, the necrosedportion becomes cast off, and an open wound remains. This as a rule marksthe turning-point in the case. The pain and other symptoms rapidly abate, and the wound, with proper attention, is not more than ordinarily difficultto treat. 

In the case of an actual wound the symptoms are probably less severe. Theinjury is, in this instance, the sooner detected, and remedial measures putinto operation. In this manner the formation of septic material is oftenchecked, and nothing but the treatment of a simple wound demands attention. 

There are, however, complications. 

_Complications--(a) Diffuse Purulent Inflammation of the Sub-coronaryTissue_. --This condition is brought about by the spread into the loosetissue of the coronary cushion of the septic material introduced by thetread. The whole coronet in this instance becomes excessively swollen, hot, and painful, and the dangerous nature of the complication is evident enoughwhen the structure and situation of the parts involved is considered. Theamount of tendinous and ligamentous material in the neighbourhood offersa strong predisposition to necrosis, and the necrosis, with its attendantformation of pus, offers a further danger when the close proximity ofthe pedal articulation and the unyielding character of the horny box isconsidered with it. 

The pus formed in this condition may remain confined to the coronet andbreak through the skin as an ordinary abscess, or it may, before so doing, burrow beneath the wall, and invade the sensitive laminæ. In this case, whenever portions of the secreting layer of the keratogenous membrane aredestroyed, or perhaps only temporarily prevented from fulfilling theirhorn-producing functions, then corresponding cavities in the horn are theresult (see Fig. 109). 

_(b) Purulent Arthritis_. --Only too readily the pus so formed tends topenetration of the articulation and the causation of an incurable arthritis(see Chapter XII. ). 

[Illustration: FIG. 109. --MESIAL SECTION OF A HOOF ILLUSTRATING THECONDITIONS FOLLOWING UPON CORONITIS. _a_, Cavity in the horn of thewall; _b_, enlargement of the coronet and the horn of the wall followingsubcoronary suppuration; _c_, cavity in the wall following purulentinflammation of the sensitive laminæ; _d_, hollow in the horn of the soleconsequent upon suppuration of the sensitive sole. ]

_(c) Necrosis of the Extensor Pedis_. --This may arise either as a resultof spreading purulent infection of the coronary cushion, or as a resultof direct injury immediately over it. The close relation of the terminalportion of this tendon with the pedal articulation, and the incompleteprotection from outside injuries here afforded to the joint by the hornybox, sufficiently points out the gravity of the condition. 

_(d) Penetration of the Articulation_. --This also may be a result eitherof the inroads made by pus, or of an actual wound. When occurring from thelatter, it is seen more often than not in the hind-foot, being there causedby the calkin of the opposite foot. Where a wound in this position ischaracterized by an excessive flow of synovia, the condition should besuspected, and, if the wound be large enough, the little finger should beintroduced in order to ascertain. Needless to say, the injury is a graveone. 

_(e) Sand-crack_. --Sand-crack is likely to result from tread when an injuryis inflicted in the region of the quarter by a severe overreach. Treads, too, especially with the calkin of the hind-shoe, are especially apt to endin this way. In this latter instance the sand-crack usually has its originin a nasty jagged tear at the top of the wall of the toe. 

_(f) Quittor_. --In one respect any suppurating wound at the coronet may bedeemed a quittor. By indicating quittor as a complication of coronitis, however, we denote the more serious form of this disease, in which thewound has taken on a sinuous character, and conducted pus to invasion ofthe lateral cartilage. It is one of the worst complications we are likelyto meet with in this condition, and will be found fully described inChapter X. 

_(g) False Quarter_. --This complication of coronitis occurs when the injuryor after-effect of the formation of pus has been severe enough to destroyoutright a comparatively large portion of the papillary layer of thecoronary cushion. To this condition we devote Section D of this chapter. 

_Prognosis_. --In giving a prognosis in a case of coronitis, attentionshould be paid to the manner in which the condition originated, and theextent, when present, of the wound. 

When the inflammatory swelling has arisen from bruising alone, withoutactual division of the skin, when the weather is that of winter, and theswelling showing a marked tendency to spread, then the prognosis must beguarded. As we have seen, this state of affairs is probably ushering ina condition of spreading suppuration of the coronary cushion, andconsiderable gangrene and sloughing of the skin. We have here no intimationas yet of how far the suppurative process may run, nor what importantstructures it may involve. Consequently, the guarded prognosis we havementioned is imperative. 

Where an actual wound is to be seen, and where advice is sought early, then a more favourable opinion may be advanced. In this case antisepticmeasures, commenced early and persisted in, may prevent the rise of furthermischief. 

It goes without saying that, should there arise any other of thecomplications we have mentioned (viz. , Arthritis, Necrosis of the ExtensorPedis, Sand-crack, Quittor, and False Quarter), the fact should be pointedout to the owner, and the prognosis regulated thereby. 

_Treatment--Preventive_. --Seeing that at any rate the majority of cases ofcoronitis result from injuries inflicted by the shoes, we may look at onceto that particular for a means of prevention. 

Take first the case of 'treads'. There is no doubt that they are mostcommon in animals shod with heavy shoes and with high and sharp calkins. This suggests at once that a preventive is to be found in substituting acalkin that is low and square. 

Where the injury is an overreach, and where, on account of the animal'space and manner of gait it is in risk of being constantly inflicted, theshoeing should be seen to at once. 

We have already pointed out that it is the inner border of the lowersurface of the toe of the hind-shoe which, in the act of being drawnbackwards, inflicts the injury. (See Fig. 110). 

In this case prevention may be brought about either by shoeing with a shoewhose ground surface is wholly concave, or by bevelling off the sharpborder (see Fig. 110, _a_, p. 236). When the tendency to overreach is notexcessive, prevention may in many cases be effected by simply placing theshoe of the hind-foot a trifle further backwards than would ordinarily becorrect, thus allowing the horn of the toe to project beyond the shoe. Thisat the same time does away with the annoyance of 'forging' or 'clacking, 'which, as a rule, accompanies this condition. 

While recognising the value of shoeing in these cases, we must not forgetthat a great deal may be brought about by careful horsemanship. The animalshould be held together and kept well up to the bit, but should _not_ beallowed to push forward at the top of his pace. With many animals of fastpace and free action overreach is more an indiscretion of youth than anydefect in action or conformation, and his powers should therefore behusbanded by the driver until the animal has settled down into a convenientand steady manner of going. 

[Illustration: FIG. 110. --UNDER SURFACE OF THE TOE OF A HIND-SHOE. _a_, Marks the portion of the inner margin that inflicts overreach. ]

[Illustration: FIG. 111. --THE INNER MARGIN OF THE INFERIOR SURFACE OF THEHIND-SHOE BEVELLED TO PREVENT OVERREACH. ]

_Curative_. --Although in some cases it is so small as to go undetected, we may take it that in all cases of coronitis there is a wound, withconsequent danger of septic infection of the surrounding parts. Therefore, after attention to the shoeing and removal of the cause, the firstindication in the treatment will be to render the parts aseptic. This isbest done by removing the hair from the coronet and soaking the whole footin a cold antiseptic solution. After removal from the bath, the coronetmay be dressed with a moderately strong solution of carbolic acid orperchloride of mercury. When the injury is slight and recent, such issufficient to effect resolution. 

When marked swelling persists, however, and the increase in heat andtenderness denotes the formation of pus, recovery is not so easilyobtained. In this case the application of hot poultices or hot baths iscalled for. By these means suppuration is promoted and induced to earlybreak through in the most favourable position--namely, the softened skin ofthe coronet. The pus so escaping is always more or less blood-stained, andcontains both large and small pieces of broken down and decomposed tissue. After discharge of the pus, the cavity remaining should be mopped out withan antiseptic solution, and a pledget of antiseptic tow or other materialleft in position. All that is then needed is constant dressing in asuitable manner. We prefer in this instance washing some three or fourtimes a day with hot water until a perfectly clean wound is obtained, and, after the washing, painting the raw surface with a strong solution (1 in200, or 1 in 100) of perchloride of mercury. 

When the abscess we have described as forming is extremely large, or whereit is more than ordinarily slow in 'pointing, ' the likelihood of its havingburrowed for some distance below the upper margin of the wall must besuspected. Here it is sometimes wise to thin the wall with the raspimmediately below the point of greatest swelling of the coronet. This willserve to lessen pressure on the sensitive structures beneath. 

Immediately the abscess contents have found exit at the coronet, the cavityformerly occupied by the pus should be explored. If to any extent it isfound then to have 'pocketed' beneath the upper border of the wall, acounter-opening should be made where the horn of the wall has been thinnedwith the rasp. 

When it so happens, either from extensive bruising or from the action ofexcessive cold, that we have or suspect the condition of sloughing, thenthe first indication is to aid the live tissues to throw off the necrosedportion. In spite of what is sometimes urged to the contrary, a hotpoultice is, perhaps, the best means of bringing this about. Directly thenecrosed piece is shed, a wound remains which, so far as treatment isconcerned, may be regarded exactly as that left by the formation of pus. Hot water applications, some three or four times daily, will serve both tocleanse the wound and also to maintain vitality in the tissues immediatelysurrounding it. After each washing, the use of a strong antiseptic solutionto the wound is again beneficial. 

In the case of an actual wound, whether, as in overreach, affecting thecoronet alone or involving destruction of part of the wall, or, as in thecase of toe-tread, penetrating the pedal articulation, the treatment to befollowed is simple enough, in theory, if not always easy to carry out. Itconsists solely in maintaining a rigid asepsis of the parts until healingis well advanced or complete. The whole foot, including the coronet, shouldfirst be thoroughly washed in warm water. At the same time there should beused some agent that will tend to remove the natural grease of the parts. In this manner cleansing will be rendered more thorough, and penetration ofthe antiseptic solution to be afterwards applied made the more certain. The most ready way of effecting this is to use the ordinary stable'water'-brush, and plenty of a freely-lathering soap. 

This done, the foot should be rinsed in cold water, and afterwardsconstantly soaked in a cold antiseptic bath. Where it is inconvenient orimpossible to have the constant bathing carried out, a dry antisepticdressing may be tried in its stead. In this case the foot should first bethoroughly washed and dressed as before. Afterwards an antiseptic powder inthe shape of a mixture of iodoform 1 part, boracic acid 10 parts, shouldbe freely dusted on the wound, a pledget of carbolized tow or cotton-woolplaced over it, and the whole maintained in position with a bandagepreviously soaked in a 1 in 500 solution of perchloride of mercury. Onceon, this dressing should be allowed to remain until healing is complete. Should the animal manifest pain, however, by constantly pawing, or shouldswelling and heat of the parts be suspected, the bandage should be removed, and the condition of the wound ascertained. 

An excellent example of the value of this method of treatment is that givenbelow:

'I call to mind a valuable hunter in my practice a few seasons since, who, whilst hunting, we suppose, struck himself in the way we suggest. He notonly removed the superior portion of the inner heel, but tore about 3inches of the hoof from the top nearly to the bottom. This was clapped backby the owner, tied with a handkerchief, and the horse removed home. Whenthe handkerchief was removed, I confess I did not think the horse looked atall like hunting again. The heel was fairly pulled down, the portion of thehoof that was hanging to it I could easily have wrenched off. The partswere fomented, however, with warm water which was slightly carbolized. Ithen removed a great portion of the heel and the lateral cartilage, whichwas split; placed the portion of hoof again on the laminæ, smothered thewound with iodoform pulv. , covered it with cotton-wool packing, and allthe boracic acid I could get it to hold. A piece of linen bandage wasthen tightly wrapped a few times round, and the lot enclosed in aplaster-of-Paris bandage. I did not undo it for a fortnight, when, tomy great pleasure, the heel and hoof presented a highly satisfactoryappearance. I did it up in much the same way for another ten days, then putthe sand-crack clamps into the hoof and fixed it to the sound part. Thehoof remained in position while the new horn grew from the top, and thehorse hunted again the same season. '[A]

[Footnote A: _Veterinary Record_, vol. Ix. , p. 501 (Bower). ]

_Sequels_. --Either of the complications we have mentioned--as, forinstance, Arthritis, Sand-crack, or Quittor--may persist and remain assequels to the case. In addition to these, there may be left behinda cavity in the horn of the wall (see Fig. 109), or a loss of thehorn-substance of the wall proper, as that depicted in Fig. 112, ordescribed under the heading of False Quarter. 

[Illustration: Fig. 112. --HOOF WITH A CAVITY IN THE SUBSTANCE OF THE WALLFOLLOWING UPON 'TREAD' TO THE CORONET. ]

The treatment of Arthritis, Sand-crack, Quittor, False Quarter, andSeedy-toe, will be found in the chapters devoted to their consideration. 

2. _Chronic_. 

_Definition_. --Coronitis in which, owing to the persistence of the cause, inflammatory phenomena continue, resulting in the growth of large fibroustumours about the coronet. 

_Causes_. --In many cases it is possible, of course, that abnormal largegrowths in this position may have an origin similar to that of neoplasmselsewhere--that is to say, an origin as yet undiscovered. There is nodoubt, however, that the majority of the huge enlargements about thecoronet have their starting-point in one or other of the diseases towhich the foot is liable, in which the cause remains, and a low type ofinflammation persists. 

In chronic and neglected suppurating corn, in untreated quittor, and inlong-standing complicated sand-crack, for instance, we have conditions inwhich pus and other septic matters find ready entrance into the subcoronarytissues. Should either of these be neglected, or should the pus formationfrom the onset take on a slow but gradually spreading form (in other words, should either of these cases run a chronic rather than an acute course)then, with the persistence of the inflammatory phenomena so caused, isbound to result a steady and increasing growth of inflammatory fibrousconnective tissue. This, as it grows, becomes in its turn penetrated by theever-invading pus, and, under the stimulus thus caused, itself throws outnew tissue. And so, constantly excited, the tumour-like mass tends tosteady increase in size, until enlargements are formed which one maysometimes truly term enormous. 

_Symptoms_. --The appearance of the growth is, of course, immediatelyevident. Usually these swellings are slow in forming, so that the sizeof the enlargement depends entirely upon its age. We may thus meet withgrowths of this description, varying in weight from 4 or 5 pounds tothe almost incredible size of 33-1/2 pounds. In the majority of cases adischarging sore is to be found upon it--in some cases several. Explored, these sores reveal their true nature. Their lip-like openings, and theready manner in which they may be searched by the probe, show them to besinuses. 

In a few cases, however, the outer surface of these tumours is intact. Whenthis is the case, it is possible that the growth is a true fibroma--that isto say, a non-inflammatory new growth of fibrous connective tissue. On theother hand, it may have resulted from one or other of the causes we haveenumerated, and its exact diagnosis have been impossible until operativemeasures had been proceeded with. In this case, small and encysted foci ofinspissated pus scattered more or less throughout the growth indicate itstrue nature. 

Pain as a rule is absent, and, unless the growth, on account of its size, interferes with progress, the animal walks perfectly sound. Here thepatient may, without offending the dictates of humanity, be put to slowwork. 

_Treatment_. --In very many cases, possibly on account of the decreasedcirculation and vitality of the parts, these growths occur in aged animals. Here treatment is not economic, and may for that reason be put out of thequestion. Further, the growths are more common in heavy cart animals of alymphatic type than in those of a lighter breed. Couple this with the factthat the tumour is often unattended with pain, and we see that the animalis still able to perform his accustomed labour. Here, again, treatment iscontra-indicated. 

For still another reason surgical treatment, which is the only treatmentlikely to be of benefit, must not be undertaken rashly. A large and openwound is bound to be left behind. So large is it in many cases that thecomplete covering of the exposed surface with epidermal growths from thecircumference cannot possibly be looked for. There is then left a large andhorny-looking scar, which is an even worse eyesore than was the originalenlargement. 

When the patient is a young and otherwise valuable animal, however, andwhen the case, judged either by the size of the swelling or its outsideappearance, promises a fair measure of success, operative measures may bedetermined on. 

In this case the author's practice has been, after casting the animal, toapply a tourniquet to the limb and proceed to excision. A lozenge-shapedincision, extending to near but not quite the circumference of theswelling, should be made with a large knife right through the skin anddeeply into the growth. The whole is then removed, proceeding in anexcavating manner under the thickened skin at the margin. Hæmorrhage, though proceeding from several apparently large vessels in the structure ofthe tumour, and oozing generally over the whole of the outer surface, is rarely profuse enough to interfere with the operation, and is easilycontrolled by cold water douches and the application of the artery forcepsto one or more of the larger vessels. The operation completed, the largerbleeding-points should be secured by exerting torsion with the arteryforceps, and the surface oozing stayed by frequent dashing with cold water. 

When the hæmorrhage has sufficiently ceased, an ordinary flat firing-ironshould be passed over the whole of the cut surface, and an effectual escharformed. 

Following this, and _before removing the tourniquet_, the wound should befilled with pledgets of carbolized tow, and the whole tightly secured by astout and broad linen bandage of not less than 6 yards in length. 

_Reported Case_. --'The patient, a middle-aged cart mare, had a pair offore-feet the like of which I never saw. As the result of long-standing andimperfectly-treated quittor all over the seat of side-bone on the outerside of each fore-foot, beginning pretty far forward, and extending to theheel on the inner side, filling up the hollow and reaching nearly to thefetlock, was a big, bulging, hard, calloused enlargement or tumour standingout 3 or 4 inches all round, covered with thick horny skin and stubby hair, and having on its surface the small openings of several sinuses leadingdeeply down to the ossified and diseased cartilage underneath. And yetwith all this diseased undergrowth the mare, strangely enough, walked andtrotted sound. I was told that this mare had been troubled with suppuratingcorns and quittor, that many unsuccessful attempts had been made at cure, but that, getting worse instead of better, these tumours had formed. 

'After casting and anæsthetizing, a strong rubber tourniquet was placedabove the knee and the operation commenced. With a surgeon's amputatingknife all the big fibrous mass which I could safely remove was cut andsliced off, and the coronet and pastern reduced as nearly as possible toits natural dimensions. The diseased cartilage, or side-bone, gave sometrouble, a considerable portion having to be cut and scraped, and the sinusin it gouged out; but its complete removal did not appear to be called for. 

'There was little if any hæmorrhage until release of the tourniquet, whenthe whole broad surface became deluged with blood, three or four smallarteries spurting and veins flowing in all directions, so much so that Iwas glad to reafix the clasp, and with the firing-iron seal up the vessels, searing gently all over the surface. 

[Illustration: FIG. 113. --CHRONIC CORONITIS FOLLOWING 'TREAD. ']

'A good dusting with antiseptic powder, a thick pad of carbolized wool, andtwo long calico bandages wound tightly round, completed the work. 

'The other, the near-leg, was then dealt with in the same way. 

'The mass removed weighed a little over 9-1/2 pounds--5 pounds from theoff-foot and 4-1/2 pounds from the near. Its structure was fibrous tissue, almost as firm and hard as cartilage, and with no appearance of malignancy. 

'The after-treatment consisted simply of fresh dry dressings--copper, sulphate, zinc sulphate, and calamine, equal parts--applied every thirdor fourth day, after first bathing the feet in a shallow tub of warmantiseptic water. 

'At the end of eight or ten weeks a fairly presentable appearance existed. The greater part of what had been raw surface was covered with healthyskin, and the remainder had become dry and horny. '[A]

[Footnote A: _Veterinary Record_, vol. Xiv. , p. 201 (C. Cunningham, M. R. C. V. S. ). ]

A further form of chronic coronitis is that shown in Fig. 113. 

This condition is commonly the result of a severe and jagged tread withthe calkin, and takes the form of an ulcerous and excessively granulatingwound. As time goes on the granulations become hard and horny-looking, andtheir fibrous tissue as hard and unyielding as tendon or cartilage. 

These if treated in the early stages with repeated dressings of caustic, or, if very exuberant, the use of the knife, usually yield to treatment. Ifneglected until the condition depicted in the figure is arrived at, thentreatment, as a rule, is of no avail. Neither is treatment of any use ifany great loss of the coronary cushion has occurred. 

D. FALSE QUARTER. 

_Definition_. --False quarter is the term applied to that condition of thehorn of the quarter in which, owing to disease or injury of the coronet, the wall is grown in a manner that is incomplete. 

_Symptoms_. --This condition of the foot appears as a gap or shallowindentation, narrow or wide, in the thickness of the wall, with its lengthin the direction of the horn fibres. By this we do not mean that thesensitive laminæ are bared and exposed. Horn of a sort there is, and withthis the sensitive structures are covered. Running down the centre of theincomplete horn is usually a narrow fissure marking the line of separationin the papillary layer of the coronary cushion, which, as we shall latersee, is responsible for the malformation. 

On either side of the indentation, as if wishing to aid further thanordinarily it should in bearing the body-weight, the horn takes on anincreased growth, and stands above the level of the horn surrounding it. Itmay, as perhaps it really is, be regarded as a form of hypertrophy, broughtabout by the increased work that the loss of substance in the region of thefalse quarter puts upon it. 

So long as the sensitive structures are protected the animal remains sound. Sometimes, however, from the effects of concussion or of the body-weight, afissure appears in the narrow veneer of horn that covers them. Into this, which, of course, is but a form of sand-crack, gravel and dirt penetrate, and so set up inflammatory changes in the keratogenous membrane. As aresult suppuration ensues, and the animal is lame. 

_Causes_. --False quarter may result from any disease of the foot thatinvolves destruction of a portion of the coronary cushion. As we may seefrom a reference to Chapter III. , it is from the papillæ of this body thatthe horn tubules of the wall are secreted. Destruction of any portion of itnecessarily results in a corresponding loss of horn in that position. Thedisease occasioning this more often than any other is perhaps quittor. Itmay also result from suppurating corn, from a severe tread or overreach, orfrom the effects of a slowly progressing suppurating coronitis. 

_Treatment_. --A radical treatment of false quarter is not to be found. Oncedestruction of the secreting layer of the coronary cushion has occurred, the appearance of the fissure in the wall will always have to be reckonedwith. A false quarter, therefore, not only renders the horse liable tooccasional lameness, but also renders weaker that side of the hoof in whichit occurs. 

The only method of treatment that can be practised, therefore, is that ofpalliation. Seeing that the trouble the veterinary attendant will have todeal with is loss of a portion of the weight-bearing surface, his attentionis immediately directed to the shoeing. As with sand-crack, so with falsequarter, the frog and the bars must be called upon to take more of thebody-weight than commonly they do with the ordinary shoe. The indication, then, is a bar shoe. At the same time, the bearing of the wall on the shoeon either side of the fissure should be eased by slightly paring it, andthe hypertrophied horn on the outer surface of the wall removed with therasp. 

In cases where penetration of the sensitive structures has occurred, complicated with the formation of pus, the same treatment as forcomplicated crack is to be followed. The foot should be poulticed forseveral days with hot antiseptic dressings, and thorough cleansing of theinfected parted brought about. Afterwards strong solutions of suitableantiseptics should be applied daily until such time as the horny coveringhas renewed itself. This done and the bar shoe applied, the fissure may beplugged with any effectual stopping. Either a mixture, such as Percival's, of pitch 2 parts, tar 1 part, and resin 1 part, melted and mixed together, or one of the artificial hoof-horns may either be used with advantage. 

E. ACCIDENTAL TEARING OFF OF THE ENTIRE HOOF. 

_Causes_. --Seeing that this accident to, and consequent severe wounding of, the keratogenous membrane nearly always occurs in but one way, it is worthyof special mention. So far as we are able to ascertain, it is an accidentpeculiar to horses continually engaged in shunting operations either inpits or station-yards. At the moment the animal is released from the waggonhe has been pulling, and should turn to the right or the left in orderto allow it to pass him, the shoe either becomes wedged in between twoconverging rails, or is trapped by the wheel of the waggon. Either theapproaching waggon with the added weight its impetus gives it then pushesthe animal suddenly away, leaving a part of his foot still fixed to therails, or the animal himself, feeling securely held, makes a sudden effortto release himself, and draws his foot cleanly out of the imprisoned hornybox. 

The author calls to mind a case in which entire removal of the horn ofthe foot of an ox occurred through the passing over it of the wheel ofa heavily-laden cart. It is therefore quite conceivable that the sameaccident might occur to the horse. As a matter of fact, we find one case onrecord where one-half of the horny box was thus removed. [A]

[Footnote A: _Veterinary Record_, vol. Xiii. , p. 129. ]

So far as we are able to gather, it is more a result of imprisonment of theshoe than of the foot. It appears, further, to be always a result of theanimal being newly shod, and the clinches firmly secured; so much so thatit would be probable, with imperfectly secured clinches, that the animalwould draw the hoof from the clinches and the shoe rather than the footfrom its horny covering. 

Therefore, as the author of one of the cases we shall afterwards relatesuggests, it should be proposed as a preventive that the shoe-nails ofanimals regularly engaged in work on the metals should not be clinched inthe regulation manner, but should have their points merely screwed off, andthe nails afterwards rasped level with the wall. 

These cases are particularly interesting as illustrating the rapid mannerin which a new hoof is afterwards formed, and the way in which the exposedsensitive laminæ take their share in adding to, though not forming the bulkof, the horn of the wall. 

From the cases we are able to record it will be seen that this accidentneed not be looked upon as fatal, nor the injury itself beyond hope ofrepair. Dependent largely upon the temperament of the animal, the amount ofpain that is caused, and the way in which the animal bears it, recovery maybe looked for. Even from the very commencement of the accident, however, the pain may be so acute and the animal so violent with it that slaughterbecomes necessary. 

_Treatment_. --This consists in applying an antiseptic and sedative dressingto the injured parts (for example, Carbolized Oil and Tincture of Opium, equal parts) and afterwards bandaging. 

From the only data we are able to work on, it appears that this dressingshould be repeated daily, the bandage being removed, each time, thefoot well bathed in warm water, and the dressing and bandage afterwardsreplaced. On first sight, it would appear that once cleansed and bandagedthe dressings might be left _in situ_ for several days. Seeing, however, that suppuration, if once set up, would add further to the intense pain theanimal is already suffering, and considering the always constant exposureof the foot to infection, it is perhaps wise to persist in daily changingof the dressings. 

At the same time, the general health of the animal should be attended to. Suitable febrifuges should be administered, either in the shape of adose of physic, or salines and liq. Ammonia. Acetatis; and the pain, ifappearing unbearable, allayed by doses of choral and hypodermic injectionsof morphia. 

_Recorded Cases_. --1. 'A short time ago I was called to see a horse whichhad had his hoof torn off in a railway "point. " When I arrived at thestable the injury had been done two hours, and the horse had been led fromthe railway to a loose-box nearly half-a-mile off. On going to this box Iwas surprised and horrified to find the poor animal mad with pain, rollingand dashing himself about. When on his back he would struggle and kick thewalls with the injured foot, as though unconscious of pain. Not one momentwas he still, and as I could see that the sensitive structures were muchdamaged by his violence, I obtained a gun and put him out of his pain. 

'The accident happened in this way. The horse was employed in shuntingcoal-waggons, and had just drawn four loaded trucks up to a point at whichthey diverged to the left, and the horse, being unhooked, ought to haveturned to the right. Here, unfortunately, the near fore-foot became wedgedin between two converging railway plates, one of which formed a part of thewaggon-way, on which the trucks were running. The horse was a big animal, and freshly shod with heavy shoes, on which a toe-piece and calkins wereused. The shoe was roughly but strongly nailed on with eight nails, theclinches of which were all firm. This shoe was fitted wide at the heels, and when the foot was fixed in the points (toe downwards) it protruded overthe face of the rail. When the trucks reached it they pressed it down, and, the horse leaning forward, the hoof was drawn off like a glove. The hoofwas almost as clean inside as if taken off by maceration--only towards thetoe was a small portion of the coffin-bone and some torn laminæ left insidethe hoof. 

'As soon as possible after the accident, so I was told, the foot was boundup with tow and a bandage; then a sack was cut up and placed over all, andthe horse slowly led to his loose-box. He "carried" the leg all the way, limping along on the three sound ones. Almost immediately after reachingthe box he lay down, but only for a short time. The standing position wasnot long maintained--profuse perspiration set in, and the alternations ofposition became more rapid and violent, till plunging and rolling wereadded to the other signs of excruciating pain. I was also told that thegroaning of the poor animal was almost constant, and at times so loud andprolonged as to amount to a shriek. 

'I have no experience of a similar case, and I should not have supposedthat this accident would have caused such acute suffering and violentsymptoms. I think I have heard of such cases making a complete recovery;but I feel sure that, in this case, I only anticipated death by, at most, afew hours. '[A]

[Footnote A: _Veterinary Record_, vol. Iv. , p. 127. ]

2. 'The case I am about to give you an account of, being one of rareoccurrence, I thought would not prove uninteresting to the members of theVeterinary Medical Association. It is an instance of complete removal ofthe hoof by mechanical force. 

'Our patient was a brown mare, five years old, the property of Messrs. Crawshaw and Co. , railway contractors on the Sheffield and Manchester line. 

'On June 20 the mare was, as usual, working on the line, drawing one of thewaggons for the removal of soil from one place to another, and, as was thecustom, the pace is generally increased at about the distance of from sixtyto eighty yards from where the unloading takes place, in order to add tothe velocity, so that the contents of the waggons might roll down so greata precipice. It was at this increased action, when the mare was beingremoved from the waggon, that she stepped between the ends of two ironrails, sufficiently apart to admit the foot only, when one end of the railinserted itself between the sole and toe of the shoe, the other at the topand in front of the crust. 

'The mare, finding herself fixed, endeavoured to disengage herself, and, indoing so, got in front of the waggon, which, coming at a great pace, forcedher down into the pit, leaving behind the off fore-hoof, which was onlyremoved from its situation between the two rails by a large hammer, itbeing so firmly wedged in. The shoe and hoof were bent in a very peculiarmanner, as the accompanying cuts will show, the inside heel beingcompletely raised from above the level of the frog, not one of the nailsbeing unclenched, or in the slightest degree having given way to so largean amount of force imposed upon them, although the toe of the shoe wasraised from the sole by the rail being immediately under it (see Fig. 114). The mare had been shod the day before, and, having a good sound foot, theshoe was firmly put on. 

'Being a mile from home, she was with some difficulty made to travel thatdistance. On her arrival, my preceptor, Mr. Taylor, was immediately sentfor, who found her, as I have before stated, with the off fore-foothoofless. 

'Proceeding to examine the foot, he ascertained that it had bledconsiderably, which, however, was stopped by bandages to the foot and aligature round the coronet. The laminæ on one side and a small portion ofthe sensitive sole, though not to any great extent, were lacerated. Thecoffin-bone was not at all injured. The bleeding having nearly ceased, she was put into slings, the foot carefully washed with warm water, andimmediately bound up with pledgets of tow saturated with the simpletincture of myrrh and tincture of opium, of each equal parts. 

[Illustration: FIG. 114. --HOOF TORN FROM THE FOOT BY ACCIDENT. ]

'The dressing was ordered to be allowed to remain on all night, and on thefollowing morning to be removed. The foot was then bathed, as before, in warm water, and the application of the tinctures repeated night andmorning. The medicine internally given was castor oil, with tinct. Opium, and this, in a diminished dose, was ordered the next morning. Blood wasalso abstracted from the jugular vein, to the amount of 6 quarts, so asto allay the inflammatory fever set up. The food consisted of bran andlinseed, with small portions of hay and water. The mare being in a highlyexcited state, and suffering such severe pain, the opinion Mr. Taylor gavewas that, should she get over the first four days (which appeared quiteuncertain), he had no doubt of her ultimately getting well, and also thatshe would have a perfect hoof formed. It was now left for the owners'consideration, whether they thought the mare worth her keep till such tookplace, the time mentioned by Mr. Taylor being four or five months. She wasseen again the fourth day after the accident, and was then found to beperfectly tranquil and feeding well; her pulse, which at the first visitcould not be counted, was now not more than 65 beats in the minute. Onremoving the dressings, the foot presented a very favourable appearance, the treatment therefore varied only in the application of a linseed-mealpoultice over the former dressings of tinctures of opium and myrrh, confining the whole in a soft leather boot. Diet as before, in addition towhich give a few oats. Should the bowels become constipated, repeat thecastor oil without the opium. 

'_June_ 28. --The animal was again seen, and appeared to be going on veryfavourably. The poultices were directed to be discontinued, and the partsdressed every other day with sol. Sulph. Cupri, as the granulations weregetting rather luxuriant. 

'_July_ 6. --To-day she was found to have gone on so well, having two daysbefore been removed from the slings, that it was thought justifiable toturn her out, protecting the foot with a boot, and ordering the dressingsto be repeated. 

'_July_ 23. --She was seen by me in the field, where I had the boot removed, and so much had she improved, that not less than 2 inches of crust, proceeding from the coronary ring, had been formed, and the foot lookedremarkably healthy. 

'It will be seen that the accident occurred on June 20, a fortnight afterwhich time I observed the horny crust to be forming from the coronet, and the insensitive laminæ at the same time, in which on every visit anincrease of growth was perceptible, and it soon attained a thicknessexceeding that of the other hoof, but which at the same time presented amore upright appearance. It was not until three weeks after our first visitthat any formation of new sole or frog was to be seen. Of the two the solewas the first, being secreted by the sensitive sole, the growth proceedingfrom the heels. In like manner the insensitive frog was being produced bythe sensitive. 

[Illustration: FIG. 115. --HOOF TORN FROM THE FOOT BY ACCIDENT. ]

'During the last week in October the mare, having her foot protected with abar shoe plated at the bottom, and so formed as to open without necessityof removing the shoe, in order to facilitate the applications of thetinctures, was put to light work, which has since been gradually increased, and she now performs her usual labour equal to any other horse. 

'The growth of the wall or crust and insensitive laminæ is not yet quitecomplete, nor is the sole, there being wanting about an inch of the hornysubstance of it, the entire completion of which I should rather doubt, as Imentioned in my former communication that the sensitive laminæ and a smallportion of the sole were lacerated, and it is in these parts that theimperfections exist. 

'The yet imperfectly-formed wall not admitting of the insertion of nailsall around it, the shoe is held on partly by nails and partly by a strapattached to it bound round the coronet. '[A]

[Footnote A: _Veterinary Record_, vol. Iv. , p. 182 (B. Cartledge). ]

3. 'This case is related by Mr. A. Rogerson, F. R. C. V. S. It occurred to ananimal regularly engaged in shunting, and happened through the corner ofthe shoe becoming "trapped" between a line of metal and the wheel ofa truck. It is particularly interesting on account of the photographaccompanying it, and which we here reproduce in Fig. 115. 

'The photograph shows plainly the manner in which the holding of the"clinches" on the left side of the hoof has resulted in drawing it offfrom the foot. Had these clinches, as Mr. Rogerson suggests, been leftunfastened, then the accident in all probability would not have occurred. The animal was destroyed. '[A]

[Footnote A: _Ibid_. , vol. Xiii. , p. 2. ]

CHAPTER IX

INFLAMMATORY AFFECTIONS OF THE KERATOGENOUS APPARATUS

A. ACUTE. 

ACUTE LAMINITIS. 

_Definition_. --The term 'laminitis' is used to indicate a spontaneous anddiffuse inflammation of the whole of the sensitive structures of the foot, more particularly the sensitive laminæ. Usually it occurs in the two frontfeet, often in all four, and occasionally in the hind alone. 

_Causes_. --In dealing with the causes of laminitis, we will first disposeof those coming under the heading of _traumatic_. Correctly speaking, however, lesions of the laminæ thus occurring do not present the samesymptoms, nor run an identical course with the disease we now purposedescribing, and for which we would prefer to entirely reserve the term'laminitis. ' The fact, however, that traumatic causes are detailed in otherworks on the same subject compels us to give them mention here. 

Strictly traumatic causes giving rise to a limited inflammation of thesensitive laminæ are violent blows upon the foot, either purely accidental, or self-inflicted by violent kicking. 

A similar limited laminitis is to be found in the conditions we havedescribed under 'Nail-bound and Punctured Foot. ' It is met with also inthe injuries resulting from tread and overreach, and in the tissue-changesaccompanying corn. 

The tenderness following upon excessive hammering in the forge, or of toolong an application of the shoe in hot-fitting has also been described aslaminitis. 

With either of the conditions we have mentioned, it goes without sayingthat there is either a simple congestion or an actual inflammation, localized or general, of the laminæ of the injured foot. In neither case, however, can the resulting mischief be closely compared with the lesionsattending an attack of laminitis proper, a disease which appears to have analmost specific cause, and to run a course peculiarly its own. 

The specific cause we have indicated as existing can, in the present stateof our knowledge, be only vaguely described as a poisoned state of theblood-stream. This, as clinical evidence teaches us, may result from avariety of causes. 

Among these, by far the most common is that state of the circulationinduced by excessive feeding with too stimulating or too irritating a diet. In any case, where the use of old oats as a staple diet is departed from, and where the quantity and manner of using the substitute is left to thediscretion of careless or unskilled attendants, trouble is likely to ensue. The food more prone, perhaps, than any other to bring about an attack iswheat improperly prepared--that is, uncooked or unground. So much so isthis the case that one full meal of this provender to an animal unused toit is sufficient to lead to a train of symptoms often ending fatally. 

Beans, peas, barley, rye, new maize, or even new oats, are all liable, ifcarelessly used, to have the same effect. 

It is the laminitis following feeding on new oats that has caused us toapply to the food the adjective 'irritating. ' Here, more often than not, the peristaltic action of the bowels is found to be abnormally in evidence, and the excessive use of the diet is always accompanied by a more or lessfluid discharge of the intestinal contents. 

In addition to the foods we have mentioned, many others might beenumerated, more especially the numerous 'made-up' feeding materials nowon the market. Many are composed of substances that may be regarded asabsolutely opposed to the correct feeding of a horse, and their use canonly be followed by this and other evil results. 

Another most fruitful cause of laminitis is a severe and continuedinflammatory condition of the system elsewhere. It is the laminitis knownto veterinary surgeons as 'metastatic, ' and perhaps the two most notableexamples of it are the laminitis following a prolonged attack of pneumonia, and the 'Parturient Laminitis' occurring as a concomitant of septicmetritis. 

Parturient laminitis it is that offers us the most striking illustration ofthe truth that a poisoned state of the blood-stream is a sure factor in thecausation of an attack. From the direct evidence of our senses (namely, manual exploration of the infected womb, and the stench of the exudingdischarge) we know that we have in the interior of the womb matter in astate of putrescence. From the experience of previous post-mortems weknow, further, that the putrescent matter thus originating often gains theblood-stream, and forms foci of septic lesions elsewhere--liver or lung. When, therefore, during an attack of septic metritis a condition oflaminitis supervenes, we are justified in attributing it to the escape ofseptic matter from the already infected uterus. 

In the same category of laminitis from metastasis may also be placed thelaminitis occurring as a result of an overdose of aloes. The enteritis thusset up is often followed by laminitis, and that of a serious type. 

Prolonged and excessive work upon a hard road is also apt to induce anattack. When this occurs it in many cases resolves itself into a case ofcruelty. (See reported case, No. 1, p. 279. )

Laminitis from this cause was frequent among coach and carriage horses inthe pre-railroad period, and resulted from attempting to obtain from theanimal a faster pace and a greater number of miles than he was physicallycapable of giving. 

In our day, however, it is more often a result of gross feeding, combinedwith only that amount of work which the horse, if ordinarily fed, wouldbe easily able to perform. An excellent example of this is the laminitisoccurring in the Shire stallion when commencing his rounds of service inthe spring and early summer. At this season these animals are constantlysupplied with a more than sufficient supply of a highly stimulating andnutritious diet. In this case the blood is already in that state in whichit is predisposed to the disease. Add to this the unwonted exercise--forduring all the winter the animals are idle--and congestion of the venousapparatus of the extremities is not to be wondered at. 

Passing from these, the more common, we may consider other and lessfrequent causes of the disease. Congestion of the laminal blood-vessels andconsequent laminitis occurs when animals are made to maintain a standingposition for prolonged periods, as, for instance, when making sea voyages. A long and painful disease of one foot, necessitating the whole of theweight being borne by the other, ends often in laminitis of the secondmember. It may thus occur as a sequel to quittor, complicated sand-crack, suppurating corn, and punctured wounds of the feet. 

Laminitis has also been known to occur as a result of septic infection ofthe blood-stream consequent on the operation of castration. (See recordedcase, No. 2, p. 281. )

A sudden lowering of the surface circulation at a time when the animal isexcessively perspiring is also said to favour an attack, as also is thegiving to drink of cold water to an animal just in from a long and tiringjourney. Also, according to Zundel, 'the influence of the season cannot bedenied, and it is during the summer months that laminitis is more frequent, while it is rare in winter, as well as in the spring and autumn. '

Further, laminitis has been described as occurring when the animal is atgrass, and when all causes--at any rate, active ones--have appeared to beabsent. (See reported case, No. 3, p. 282. )

Regarding heredity, we may safely say that, as a cause of laminitis, it maybe almost totally disregarded. That a bad form of foot, either a flat-footor a foot with heels contracted, and already thus affected with a mild typeof inflammation, did not offer a certain predisposition, we should not liketo assert. There must, however, be an exciting cause--namely, a poisonedcondition of the blood-stream. This latter cannot, of course, be in any wayregarded as hereditary. 

In short, the dietetic cause is by far the most common, and, in prosecutinginquiries as to the starting-point of an attack, the veterinarian'sattention should be directed in the main to that particular. 

_Symptoms_. --Laminitis is always ushered in by a set of symptoms indicativeof a high state of fever. The pulse is raised from the normal to as many as80 or 90 a minute, muscular tremors are in evidence, the respirations areshort and hurried, and the temperature rises to 105°, 106°, or 107° F. Thevisible mucous membranes are injected, that of the eye, in addition to thehyperæmia, often tinged a dirty yellow. The mouth is dry and hot, the urinescanty, and the bowels frequently torpid. As yet, however, the walk issound. 

Called in during this early stage, the veterinarian is often puzzled asto the exact significance of the symptoms. Enteritis, lymphangitis, orpneumonia he knows to be often heralded in the same manner. In thisconnection, Zundel says: 'Laminitis, in most instances, is preceded bycertain general symptoms, such as are premonitory of the invasions ofordinary inflammatory diseases, but of an uncertain significance. '

So far we agree with him, but to what we have already said we would addthat, even in this early stage, there is an additional symptom, unmentionedby Zundel, which often leads one to an exact diagnosis. The feet are inturn lifted a short distance from the ground, and almost immediatelyreplaced. This movement ('paddling, ' we may term it) is constant, theanimal appearing to obtain ease in no one position for more than a fewmoments at a time. 

Seen but a few hours later, when the swelling caused by the hyperæmiaand outpouring of the inflammatory exudate has led to compression of thesensitive structures within the horny box, the symptoms presented admit ofno misreading, save by the most casual and careless observer. The patientnow stands as though fixed to the ground. The pulse is hard and frequent, the respirations tremendously increased in number, the body wet with apatchy perspiration, and the countenance indicative of the most acutesuffering. Only with difficulty, and often only at the instigation of thewhip, can the animal be induced to move. This he does by throwing hisweight, so far as he is able, on to the heels of the feet affected, andputting the feet slowly forward in a shuffling and feeling manner. The feetthemselves give to the hand a sensation of abnormal heat, percussion uponthem with the hammer is followed by painful attempts at withdrawal, whileany effort we may make to remove one foot from the ground is useless, sogreat an aversion does the animal show to placing a greater weight upon theopposite foot. 

According as the front-feet alone, the hind-feet alone, or all four feetare affected, the symptoms will vary. 

With all four feet diseased, the animal stands with the two front-feetextended in front of him, while the hind-limbs are at the same time proppedas far beneath him as is possible. The horse is, in fact, standing upon theextreme hindermost portions of the feet. 

Why the animal should thus distribute his weight is easily explained. Standing in the normal position, the body-weight is borne by the sensitivelaminæ, the sole, of course, sharing in the burden, but the laminæ takingby far the greater part of the pressure thus exerted. With the vessels ofthe laminæ gorged with blood, and the laminal connective tissue infiltratedwith a profuse inflammatory exudate, the most excruciating pain is boundto result by reason of the compression of the diseased tissues within thenon-yielding structures. In some little measure the suffering animal mayafford himself relief by partly removing pressure from the fore-parts ofthe hoof. When placing the body-weight behind, the pressure, instead offalling upon the highly sensitive laminæ, is directed to the follicular andfatty tissues of the plantar cushion: from there, with only a small portionof the sensitive sole intervening, to the horny frog, and from thence tothe ground. 

The same distribution of weight also places the foot in a position ofgreatest expansion, thus, by giving greater room to the diseased parts, again affording relief of pressure on the inflamed lamina, while it at thesame time relieves of weight the foremost portions of the sensitive sole. 

With the fore-feet alone attacked, the animal affects exactly the sameposition of standing as that just described. The fore-feet are againextended, and the hind propped far beneath him. The fore extended, in orderto obtain the relief occasioned by standing on the heels; the hind in thiscase carried forward in order to take a greater share of the body-weight, and thus relieve the congested members in front. 

With the hind only attacked, then the fore and the hind feet are moreclosely approximated than in the normal position. The reason, of course, is that the hind-feet are carried forward in order to be placed upon theheels, while the fore are taken backwards to relieve the hind of thebody-weight. 

In like manner the movements of the animal will vary with the feetaffected. With only the front-feet diseased the animal is, comparativelyspeaking, comfortable. The hind-feet take the weight, and the animal standsfor long periods together, resting alternately first one fore-foot and thenthe other, moving often in a circle of which his body is the radius, andhis hind-limbs the centre. If urged to move forward, then immediately hiscountenance and movements manifest the pain to which he is put. Only withreluctance does he cause the fore-feet to take weight. They are shuffledforward quickly one after the other, so that weight may not be placedupon them for one instant longer than is necessary, and the hind-limbsimmediately brought again with two short, awkward movements beneath thebody. Progress thus takes place in a succession of movements 'half hobble, ''half jump. '

Painful though this may appear, progress is still more difficult when thehind-feet alone are diseased. Afraid that, in placing his fore-membersfreely forward, he will add to the pain in his hind, the walk takes placein a series of extremely short steps, with the feet more or less closelyapproximated. The gait is thus rendered extremely awkward, and Zundel, bysaying that 'the animal appears as if treading on sharp needles, ' mostfitly describes it. 

Movement with all four feet affected, though less awkward in appearance, is doubtless more painful than in either of the other conditions. Herethe animal can hardly be induced to shift his position at all. Only byflogging, and that severe, can he be made to go forward. When so induced tomove, the agonizing pain to which the patient is subjected may be gatheredby noting his countenance and manner of progression. 

With each movement forward, muscular tremors affect the limbs; each stepis short, jerky, and convulsive; the respirations and pulse are almostimmediately greatly quickened, and the lower lip is hung pendulous, andmoved almost unconsciously up and down with a flapping noise against theupper. A patchy perspiration breaks out about the body and quarters, andthe tail is outstretched and quivering. At the same time the lines of theface become drawn, the commissures of the lips pulled upwards, the eyesstaring and haggard, the eyelids puckered, the nostrils extended, andthe whole expression indicative of the intense and agonizing pain of thedisease. 

One can perhaps better give one's client some vague idea of the patient'ssuffering by likening the pain to the throbbing sensation of a festeredfinger-nail. Tell him that each hoof of the horse is similarly, or, ifanything, more delicately, constructed, that in each foot the same processof 'festering' is going on, and that upon them the animal has perforce tostand. 

As one might expect, the position of greatest ease is the decumbent. Strange to say, though, in many cases of laminitis the animal persists inmaintaining a standing posture. Once down, however, one has sometimes thegreatest difficulty in persuading him again to rise. The lying position isso long maintained that bedsores begin to make their appearance, and theanimal rapidly loses flesh, not only by reason of the fever and the pain, but by giving to rest the time he should normally give to feeding. 

Difficulty in rising is greatest when all four feet are affected; is_nearly_ as great when the hind-limbs only are in trouble, but is leastwhen the disease exists alone in the two fore-feet. 

THE COURSE OF THE DISEASE AND ITS PATHOLOGICAL ANATOMY. --As withmost inflammations of any severity, so with this we may consider thepathological changes taking place in the foot under three headings: (a)The period of Congestion; (b) the period of Exudation; (c) the period ofSuppuration. 

(a) _Congestion_. --In the early stages of laminitis there is a state ofengorgement of the vessels of the keratogenous apparatus generally, butmore particularly the laminal portion of it. With the hoof removed at thisstage the sensitive laminæ are found to be swollen, dark red in colour, andaffording a distinct feeling of increased thickness when pressed betweenthe fingers, Incised, there escapes from the cut surface a large flow ofdark venous-looking blood. At this stage hæmorrhages of the laminal vesselsoccur. The escaping blood infiltrates the surrounding connective tissue, and in many cases destroys the union between the horny and sensitivelaminæ. This change is most noticeable in the region of the toe and thecommencement of the quarters, the os pedis appearing as though pushedbackwards by the escaping fluid collected between the wall and the bone. Insevere cases, fortunately but rarely seen, the blood so escaping continuesto infiltrate, and separate the tissues until it is seen to be freelyoozing at the region of the coronet. (See reported case, No. 1, p. 279. )

(b) _Exudation_. --The period of exudation marks the outpouring of theinflammatory fluid. This, even more than the hæmorrhages attending thestage of congestion, tends to destroy the intimacy between the sensitiveand the horny laminæ, leading finally to their complete separation atthe region of the toe. Fig. 116 illustrates this state of affairs afterlaminitis has existed for a week. The sensitive and horny laminæ are hereshown to be distinctly separated from each other, a well-marked cavityexisting between them, which cavity is greatest in extent at the toe of theos pedis. With the sensitive structures thus detached from the wall, it isevident that very much that formerly held the os pedis in normal positionhas been destroyed. What then happens is that the whole of the body-weightis placed upon the sole. Never intended to bear the strain thus imposed, it naturally sinks. With the sinking is a corresponding 'dropping' of thepedal bone--in fact, of the whole of the bony column. Seeing that thestructures _above_ the hoof are still normally adherent to the bones, itfollows that they must, as the os pedis sinks, be carried with it. As aconsequence we get a marked depression at the coronet (see Fig. 117, _a_), which depression may be often noticed after the second or third week of asevere attack of the disease. 

[Illustration: FIG. 116. --LONGITUDINAL SECTION OF A FOOT WITH LAMINITIS OFEIGHT DAYS' STANDING. The separation between the sensitive structures andthe hoof is indicated by a dark line. The cavity is filled with exudate. Itwill be noted that as yet there is little change in the position of the ospedis. ]

Here, again, though to a greater extent than that caused by the hæmorrhagealone, the os pedis appears to be pushed backwards, the space at the toebetween the bone and the horny box being closely filled with the yellow, slightly blood-stained exudate. This condition is well depicted in Fig. 117. 

[Illustration: FIG. 117. --LONGITUDINAL SECTION OF A FOOT WITH LAMINITIS OFFOURTEEN DAYS' STANDING. _a_, The depression at the coronet caused by thedropping of the bony column within the horny-box: _b_, a portion of thesensitive sole pushed downwards and forwards by the descending os pedis. ]

With the descent of the os pedis we get in many cases a penetration of thehorny sole (see Fig. 117), leading always to serious displacement of thesensitive sole (see Fig. 117, _b_), and often to caries of the exposedbone. 

The backward displacement of the os pedis may be accounted for in two ways. Firstly, the greater vascularity of the membrane covering its front leadsto a greater outpouring of inflammatory fluid in that particular position. Here, therefore, loss of adhesion with the wall is greatest, while into thecavity so formed is poured a large quantity of a fluid that is practicallyincompressible. The os pedis _must_ be pushed backwards. Secondly, themanner in which the animal distributes his weight--namely, upon theheels--is calculated to aid in the bone's backward movement, for with hisfeet in this position tension upon the extensor pedis is relaxed, whilethat upon the flexor perforans is greatly increased. 

(c) _Suppuration_. --Should the animal survive the pain and exhausting callsmade upon his system by the accompanying fever of the foregoing conditions, the case ends either in resolution or suppuration. When suppuration occursit is found, as a rule, at the sole, leading to almost entire separation ofthe sensitive and horny structures. The pain, if possible, is even worsethan in either of the foregoing stages, and relief for the sufferingpatient is only obtainable by the natural exit of the pus at the coronet, or by giving it escape with the knife at the sole. As a rule, suppurationin laminitis is rare, and then only occurs when the disease has been ofsome several days' duration. It has been the author's experience, however, to meet with it in a case but three days' old. This particular animal hadlaminitis restricted to the hind-feet. The condition was diagnosed and pusliberated at the sole of one foot during the third day of the lameness. Theanimal was cast on the fourth day, and pus obtained from the sole of theopposite foot. 

_Complications_. --In a moderate case, carefully treated, laminitisterminates at the end of three or four days in resolution. The generalsymptoms of fever gradually subside, the appetite returns, and the walkbecomes easier. Cases thus terminating fortunately leave behind them nochange of serious importance, either in the sensitive tissues or in thehorny envelope. Should resolution, however, be longer delayed, then thecase, although eventually terminating successfully so far as soundness ingait is concerned, leaves more or less evidence behind in the shape ofrings about the wall and alterations in the build of the sole. 

When the happy ending of rapid resolution is denied us, then, in additionto the condition we have described as suppuration, we may meet with one orother of the following complications:

_(a) Metastatic Pneumonia_. --This complication is not uncommon, and, when occurring, more often than not ends fatally. It may be accounted forindirectly by the greater work the lungs are called upon to perform incarrying out the increased number of respirations occasioned by the generalfever and pain, and directly by the poisonous materials circulating in theblood-stream. 

_(b) Metastatic Colic_. --This may be either a subacute obstruction of thebowel or an enteritis accompanied by an offensive purge. 

A striking case of the former is related in the _Veterinary Journal_ (vol. Xvi. , p. 180) by H. Thompson, of Aspatria. Here no evacuation of the bowelsoccurred for three days, and the pains of laminitis were added to by theusual pains of intestinal obstruction. 

The colic of enteritis is in some cases caused by the nature of the food, giving rise to laminitis. In our opinion, however, it is more oftenoccasioned by the drastic action of the aloes nearly always resorted to inthe treatment of the disorder. As does the pneumonia, the enteritis thusbrought about nearly always has a fatal termination. 

_(c) Gangrene of the Structures within the Hoof_. --This complication isthe one most to be dreaded. It occurs as a result of the great pressureexerted by an excessive exudation, and doubtless affects first the laminæand softer structures. Once commenced, however, it rapidly extends to deathof the other structures (ligament, tendon, and even bone), and gives afatal ending to the case. 

That gangrene of the tissues ("mortification" as our older writers calledit) has occurred is soon made evident to the veterinarian by the symptomsshown by the patient. The agonizingly acute pains suddenly subside, thefeet are placed firmly and squarely to the ground, and the animal walkswith ease. Perhaps but the night before the patient is seen racked withexcruciating pain; the morning sees the astounding change of apparentabsolute recovery. Too well, however, the eye of the experienced veterinarysurgeon sees that such is not the case. Even before proceeding to take arecord of the other symptoms, he knows that it is but the commencement ofthe end. Methodically, however, he notes the other conditions. The pulsehe finds small and imperceptible, save at the radial. The thermometerregisters a subnormal temperature, the extremities are cold, and coldsweats bedew the body. To the same experienced eye the countenance of theanimal is almost suggestive of what has occurred. The drawn and haggardexpression, to which we have previously referred, becomes more marked, andthe angles of the lips are drawn back in what has been described by somewriters as a 'sardonic' grin. 

We can best express what the whole look of the animal's countenanceindicates to us by saying that it gives us the impression that the animalhimself knows that some serious change, and a change fatally inimical tohis chances of life, has taken place in his feet. 

It may be that in some odd cases, although it has not yet been our lot tomeet with them, gangrene may terminate in the casting off of one or morehoofs. Needless to say, there can still be but one termination to the case. 

_(d) Periostitis and Ostitis_. --This complication is referred to by otherwriters under the term of 'Peditis. ' It signifies, of course, that theperiosteum and the bone have become invaded by the inflammatory process. It is our opinion that these two conditions, even including an actualarthritis, always exist, even in an attack of laminitis that endsfavourably. We do not claim, however, to be able to relate any means, savethat of post-mortem examination, by which it may be singled out from theother changes occurring in the foot. The high fever and pain occasioned bythe inroads of the inflammation into the other sensitive structures servesto effectually mask whatever evidence of it we might otherwise obtain. It may be sometimes only small in degree, but we feel confident thatinflammation, at any rate of the _outer_ layer of the periosteum, is inlaminitis constant even, we repeat, in a mild case. 

[Illustration: FIG. 118. --SHOWING CHANGES IN THE OS PEDIS WITH LAMINITIS OFLONG STANDING, (_a_, Viewed from the front; _b_, viewed from the side. )The porous condition of the bone, which is here shown, is a result of ararefying or rarefactive ostitis. This specimen also illustrated (what thephotograph cannot show) an accompanying condition of condensation of bone, or osteoplastic ostitis. (For a fuller description of the changes occurringin these forms of ostitis, see Chapter XI. )]

When the case is a serious one we have ample evidence to show that ostitisexists, and exists in a severe form. The bones become vastly altered inshape, a process of absorption leads to the formation of large, irregularcavities within their substance, and what of the bone is left is renderedhard and ivory-like (condensed) near what was the original centre, whilethe edges and other portions show often a tendency to become brittle andporous. 

Fig. 118 illustrates the effects of a severe ostitis in pedal bones removedfrom hoofs with laminitis of several weeks' standing. 

_(e) Chronic Laminitis_. --The most common complication--or, perhaps, rather we should term it 'sequel'--to acute laminitis is the chronic formof the disease. For this condition we have reserved a separate section ofour work. It will be found described in Section B 1 of this chapter. 

_Diagnosis and Prognosis_. --One is almost tempted to state that thediagnosis of laminitis offers no difficulty. In the very early stages, however, it may, as we have already indicated, be mistaken for the oncomingof Enteritis, Lymphangitis, or even Pneumonia. The paddling of the feetmay help us. If this is absent, however, nothing but a most carefulexamination, or, if necessary, the withholding of our opinion until thefollowing visit will prevent a blunder being made. 

Even when well established, laminitis has been mistaken for paralysis, for tetanus, for rheumatic affections of the loins, or even for someundiscovered affection of the muscles of the arms and chest. This latter isno doubt suggested to the uninitiated by the reluctance the animal shows tomove the muscles _apparently_ of that region, and led the older writers togive to the disease its name of 'Chest-founder. ' It is only fair to add, however, that these blunders in diagnosis are nearly always committed bypersons without a veterinary training. 

Thus warned, the veterinary surgeon of average ability should have nodifficulty in establishing a distinction between the diseases we haveenumerated as likely to be confounded with it, and the one this chapter isdescribing. 

The prognosis in laminitis should, in our opinion, always be guarded. Noadvice given in a work of this description can be of any real use, forevery case must be judged entirely on its merits. The severity ofthe symptoms, the cause of the attack, the complications, and theidiosyncrasies of the patient, have all to be taken into account. These theveterinarian must be left to judge for himself. 

_Treatment_. --The treatment of acute laminitis in its early stage must bebased upon the fact that we have to deal with a congested state of thecirculatory apparatus of the whole of the keratogenous membrane. This factwas well enough known to the older veterinarians. It is not surprising, therefore, to learn that jugular phlebotomy was at once resorted to as thereadiest means of relieving the overcharged vessels of their blood. As amatter of fact, bleeding from the jugular is still advocated by modernauthorities. We cannot say, however, that we unhesitatingly recommend it. Mechanically, of course, the removal of a large quantity of blood isbound to result in a lowering of the pressure in the vessels. The effect, however, is but transient. Blood removed in this way is again quicklyreturned to the vessels so far as its fluid matter is concerned, and thepressure, removed for a time, is again as great as before. With theother and more vital constituents of the blood-stream--namely, thecorpuscles--restoration is not so rapid. We have, in fact, a weakened stateof the system, in which it is probable it will not so successfully combatthe adverse conditions the disease may induce. 

With these prefatory remarks, we may advise bleeding under certainconditions. The quantity removed must be moderate (7 to 8 pints), and thepulse and other conditions must show no signs of weakness or collapse. 

Local bleeding, either from the toe or the coronet, is also advised. Inthe former situation the sole is thinned down until a sufficient flowis obtained, while at the coronet scarification is the method adopted. Bleeding locally, however, is far less effectual than the jugularoperation. Neither must it be forgotten that wounds in these situations, more particularly at the toe, are extremely liable, especially withthe existing poisoned state of the blood-current, to take on a septiccharacter. What might possibly have remained a comparatively simpleinflammation is induced by the operation itself to terminate in the morecomplicated and serious condition of suppuration. 

Other means of combating the congested state of the membrane areprincipally those of local applications. With many veterinary surgeons warmpoulticing is still largely advocated and practised. We do not believe init. Warmth, as a means of removing local congestion, can only be successfulwhen applied _widely_ round the congested area, and so dilating surroundingbloodvessels and lymphatics. Applied to the congested area itself, and tothat alone, it is almost worse than useless. 

With the foot, both around and below it, a surrounding area is denied us. The only vessels we are able to dilate with the warmth, and so enable themto carry off the fluid from the congested foot, are those in thelimb above. That poulticing cannot be successfully there applied isself-evident. Apart from that, it is an open question whether poultices maynot do actual harm in inducing suppuration in cases where, probably, itwould not otherwise occur. 

For these reasons we hold to the opinion that when a local application isdetermined on it should be a cold one. Various methods of applying cold arein vogue. Cold swabs are perhaps most in favour. They must, however, be_kept_ cold. When a suitable water-course, pond, or other expanse ofshallow water is at hand, then the animal may be kept standing therein, orpreferably walked about in it. When suitable apparatus is obtainable, aconstant stream over each foot from a rubber hosepipe is most beneficial. 

Astringent baths, containing solutions of alum, of copper sulphate, of ironsulphate, or of common salt, or composed of a mixture of two or more of thesalts mentioned, may also be used with advantage. In addition to the factthat such solutions are for a time below the temperature of simple water, we have the advantage that they have also a more or less antisepticproperty. 

While on the subject of the relief of the congestion, we must not forgetto mention a treatment which we ourselves have practised with considerablesuccess--namely, that of forced exercise. It appears to have been firstbrought into prominence by Mr. Broad, of Bath, and the two terms 'ForcedExercise and Rocker Shoes' and 'Broad's Treatment' have come to besynonymous. 

The Broad shoe is a shoe with a web of quite twice the thickness of theanimal's ordinary shoe, and has this web gradually thinned from the toebackwards until at the heels the shoe is at its thinnest (see Fig. 119). 

The excessive thickness of the shoe serves two purposes. It allows of therequisite amount of slope being given to the web, and so enables the animalreadily to throw himself back on to his heels, a position in which, as wehave already indicated, he obtains the greatest ease. It also minimizes tosome extent the effects of concussion. 

[Illustration: FIG. 119. --SEATED ROCKER BAR SHOE (BROAD'S) FOR TREATMENT OFLAMINITIS. ]

With forced exercise, as practised by Mr. Broad, this shoe is firstapplied, and the animal afterwards made to walk upon soft ground, or evenupon the roadway, for a half an hour to an hour and a half three times aday. 

For our own part, we consider the shoe to be almost if not quitesuperfluous, so far as its influence upon the progress of the disease isconcerned. We therefore dispense with it, and have the animal exercised inhis ordinary shoes. To do this, the patient has sometimes to be severelyflogged into taking the first few steps. After that progress graduallybecomes easier. 

It has been said to be cruel. In so far as we knowingly, and of setpurpose, occasion the animal pain, cruel it undoubtedly is; but it iscruelty with an aim that is truly benevolent, and the object of ourbenevolence is the animal upon whom the cruelty is practised. 

One word of advice is needed. The forced exercise must be commenced early. In the later stages, when the stage of congestion has passed from thatto the acuter stages of the inflammation and the outpouring of theinflammatory exudate, then forced exercise cannot be safely commenced. Theloss of adhesion between the pedal bone and the horny box, which we know tobe then existent, negatives its advisability. 

By many it is advised to always remove the shoes. From what we have alreadysaid, it will be seen that this is not our practice. But one argumentin favour of so doing appears to us to carry weight, and that is that'dropping' of the sole is probably prevented from becoming so marked. Thatcondition, however, is entirely dependent upon the changes occurring withinthe horny box. It is bound to occur with the animal shod or unshod, andto reach a stage when only contact with the ground prevents its furtherdescent. The complication then sometimes following--namely, penetration ofthe sole by the bone, is not prevented by having the shoes removed. It may, in fact, be thus rendered more likely. 

Internal treatment consists in the exhibition of suitable febrifuges andthe administration of a dose of aloes. 

With regard to the wisdom of the latter proceeding, opinion seems to bedivided. Personally, we hold an open mind concerning it. This much iscertain: in many cases of laminitis--those cases which have their originin overfeeding with an irritating food--there is already a strongpredisposition to enteritis. The administration of aloes in this caseis extremely apt to induce a fatal super-purgation. Aloes is, again, contra-indicated when the laminitis is a result of excessively longjourneys, and the patient is already greatly exhausted. Neither can it beadvocated in the laminitis occurring as a sequel to septic metritis or topneumonia. 

On the other hand, when the disease has occurred as a result of longstanding in the stable and an overloaded condition of the bowels, or whereone full meal of some constipating food, such as whole wheat, pea or beanmeal, wheat or barley meal, has occasioned the attack, then a dose of aloesat the commencement of the treatment is productive of good. 

Suitable febrifuges are found in potassium nitrate, potassium chlorate, sodium sulphate, or magnesium sulphate, either of which or a mixture of twoor more of them, the animal will readily take in his drinking-water. 

The administration of sedatives is also indicated. In this connectionaconite will be found most useful. More especially in the early stages ofthe disease, when pain is excessive and the temperature high, will itsgood effects be noticed. This also the animal will often take in hisdrinking-water. We have been in the habit of so prescribing the B. P. Tincture in 1/2-dram doses three times daily. By its use the temperature israpidly lowered, the pulse reduced in number and in fulness, and the painin some instances perceptibly diminished. With others hypodermic injectionsof morphia and atropine have given equally satisfactory results. 

Needless to say, good nursing is a _sine quâ non_. During the firststages of the fever a light and easily digested diet should beallowed--bran-mashes, roots and grass when obtainable, and a carefullyregulated supply of water. The animal should be warmly clothed and the boxwell ventilated, even to the opening of the doors and windows. Only in thisway is pneumonia as a sequel sometimes prevented. The patient's comfortshould be attended to in providing him with a suitable bed. Anything inthe shape of long litter should be avoided. When nothing else is at hand, litter that has already been broken and shortened by previous use is best. With this the box floor should be thickly covered, and matting of thematerial prevented by constant turning. A good bed for the horse withlaminitis is peat-moss mixed with short straw. This, without beingdragged into irregular heaps, remains springy and elastic with but littleattention. Better than all, however, especially with good weather, is anopen crewyard. Here the animal has an abundance of fresh air, has a bedthat is always soft, and has plenty of room in which to get up and downwith some degree of ease. 

Leaving the dietetic and medicinal, we may consider other treatments oflaminitis that come more particularly under the heading of operative. 

The first matter that here demands our attention is that of allowing theexudate to escape at the sole. If after the expiration of three or fourdays pain and other symptoms of distress continue, then it may be judgedthat the inflammatory exudate has made its appearance. Operative measuresallowing of its escape, though not giving absolute ease, do undoubtedlyrelieve the more marked expressions of suffering, and should be at oncedetermined on. To do this completely it is necessary to cast the animal. The sole is then thinned at the toe with the drawing-knife until thesensitive structures are reached. A flow of yellow and sometimesblood-stained discharge is immediately obtained, and the sole itself foundto be underrun to a considerable extent. An opening sufficiently large toadmit of free drainage (about the size of a half a crown-piece) is made, the wounds antiseptically dressed, and the hobbles removed. 

If showing an inclination to do so, the animal should then be allowedto remain and rest. In one instance in which we so operated (a case oflaminitis in the hind-feet alone), the relief given was at once manifested. For three days previously the animal had remained standing in agonizingpain. On the fourth he was cast, and the discharge--partly inflammatoryexudate, and partly a sanious foetid pus--liberated. The hobbles wereremoved, and the animal allowed to remain down while our attention wasdrawn to another case. This attended to, we walked back to the fieldwhere, our first patient was lying. His breathing, but a short time beforedistressedly short and catching, was now so slow and deeply regular thatfor one brief moment the thought flashed across our mind that he was dead. He was in a _profound_ sleep. 

Other operators sometimes give the exudate escape while making the groovesin what is now known as 'Smith's Operation. '

In this operation the hoof is so grooved as to allow of its expansion, sorelieving the pressure on the sensitive structures within it. Incidentally, the inflammatory exudate is given exit. 

[Illustration: FIG. 120. --DIAGRAM OF HOOF SHOWING THE POSITION OF THE THREEGROOVES MADE IN THE TREATMENT OF LAMINITIS. ]

The animal is cast, the shoes removed, and three vertical grooves madein the wall. The first is cut down the centre of toe, extending from thecoronet to the ground surface. The second is made to the right of this, andthe third to the left, each following the direction of the horn fibres, andeach distant about 2 inches from the first (see 1, 2, and 3, Fig. 120). 

Each of the grooves must run completely from the coronary margin to theground surface, and each should be carried through the substance of thehorn until the horny laminæ are reached. This done, the underneath surfaceof the foot is grooved at the white line (see curved groove 4, Fig. 121)in such a manner as to entirely isolate the two pieces of horn _a_ and _b_from the remainder of the hoof. 

Expansion of the horny box is thus brought about, while at the same timethe semicircular groove at the toe is made deep enough to allow of theescape of the exudate. 

If thought wise by the operator, the two pieces of horn _a_ and _b_ may beisolated, and the exudate given exit by making the fourth groove in theposition of the dotted lines in Fig. 120--that is to say, at the lowermostportion of the sensitive structures. By this means the sole will be leftintact. 

[Illustration: FIG. 121. --LOWER SURFACE OF FOOT SHOWING POSITION OF THEGROOVES MADE IN THE TREATMENT OF LAMINITIS. ]

Fuller instruction for making the grooves and the instruments required willbe found described in Section C of Chapter X. 

The animal should be afterwards shod, and the bearing on the portions_a_ and _b_ of the wall removed. Almost immediate relief is afforded thepatient. 

_Recorded Cases_. --1. 'On the evening of September 28 last, I was calledrather hurriedly to attend a posting-horse which had just arrived from atwenty-one miles' journey, and was said to be "very ill. " I lost no time inproceeding to the spot, and found my patient "very ill" indeed. No need forlong consideration as to diagnosis; the symptoms showed at once that I hadan uncommonly severe case of acute founder before me. On examination Ifound the pulse was 120, the respirations 100, and the thermometer 106° F. The poor brute could not move, the fore-legs were well out before, and thehind-legs thrown back behind; in fact, he was, as one might say, proppinghimself up with his four legs!

'On examining his feet, I discovered what I had never either seen or heardof before--namely, _blood freely oozing out_ at the coronet of all fourfeet; if anything, the hind-feet were the worst, and, showing that thisbloody discharge at coronets had commenced during progression and beforehe was stabled, the inside of the thighs were all shotted over with blood, which had been thrown up by his feet while he was trotting or walking. Hewas completely soaked all over with perspiration. 

'My prognosis could not well be otherwise than unsatisfactory. I resolved, however, to do all I could to relieve the poor suffering brute. As a matterof course, jugular phlebotomy was utterly impracticable; so, to relieve thepressure in the feet, I had him (after, with extreme difficulty, removingthe shoes) bled, or rather opened, at all four toes, and hot poulticesapplied. On opening the off-side toe, in both hind and fore feet, I foundan escape of very dark-coloured blood, with a great many bubbles of gas, thus showing that the destructive process was fairly established in thetwo bony extremities mentioned. The near fore and near hind feet showed nosigns of gas-bubbles on being opened at the toe. 

'I gave a laxative in combination with a diffusible stimulant, and ordereddoses of aconite and potassium iodide; I also applied strong sinapisms toeach side, immediately behind the shoulders. After three hours I found mypatient rather easier; respiration about 90, and temperature 104°; willingto take a little water, and even attempted to take some hay. Orderedcontinued applications of hot water to the poultices at feet, andclothed him up for the night. Next morning there was little improvement;respirations over 80, and temperature 103. 5°. Continue same treatment. Second morning, horse apparently easier; temperature 102. 5°, but verydifficult respiration; laxative had operated during the night; ordereddiffusible stimulants. About two hours and a half after my last visit, thehorse turned round in his stall and dropped down dead!

'_History of the Horse_. --He belonged to an extensive horse-hiringestablishment; was purchased a short time before for £60--a long price fora post-horse--had recently suffered and been off work from some "severecold"; was taken out, and did forty-seven miles of a journey the day_before_ I saw him; on forenoon of the day on which he was attacked he didtwo or three short turns, and then twenty-one miles of a journey in theafternoon, during which he became so ill as scarcely to be able to concludethe twenty-one miles; this was the last turn he was to do. He was a grandstepper, and no doubt was pushed a little during this final journey, asthe driver intended, after a short rest, to finish off with the twenty-sixmiles between this and home. With the short turns on the second forenoon, this would have been over 100 miles in less than two days, with a horsejust out of a _severe cold_. '[A]

[Footnote A: _Veterinary Journal_, vol. Xvii. , p. 314 (A. E. Macgillivray). ]

2. 'Whilst attending a patient on a farm on September 5 last my attentionwas called to a cart-horse, five years of age, that had been castrated inthe standing position by a travelling castrator about ten days previously. 

'I found the animal presenting the following symptoms: Head down, blowinghard, very dull, and disinclined to move, temperature 105° F. , hard, rapid, slightly irregular pulse, membranes injected, appetite lost; scrotum, sheath, and penis tremendously swollen, castration wounds unhealthy, andexuding a thin, reddish-brown discharge of a most foetid odour. 

'The next day well-marked symptoms of laminitis were present. I finallyceased attending him about the middle of October, and at the end of thatmonth he was turned out for the winter. '[A]

[Footnote A: _Veterinary Record_, vol. Xiv. , p. 649 (Charles A. Powell). ]

3. 'On July 8 an interesting case of laminitis came under my notice. Thesubject was a mare, eight years old, which had been running on the commonhere for some months, and was taken up on the night of July 2 by a boy, who did not observe anything amiss with her. The following morning, on theowner going to the stable, he found the animal in great pain, and at oncesent for me. I discovered her to be suffering from laminitis, and saw heragain in the evening, when she was much worse. The attack proved to be amost severe one. 

'The owner informed me that she had not been allowed any corn for twomonths, and that she had no distance to travel on the road from the common. 

'Though on such a poor pasture, the mare was very fat; she had never beenunwell before this attack. 

'This is the first case I have seen of laminitis occurring when the animalwas on grass. '[A]

[Footnote A: _Veterinary Journal_, vol. Ix. , p. 176 (W. Stanley Carless). ]

B. CHRONIC. 

1. CHRONIC LAMINITIS. 

_Definition_. --A low and persisting type of inflammation of the sensitivestructures of the foot, characterized by changes in the form of the hoof, and incurable pathological alterations within it. 

_Causes_. --Chronic laminitis more often than not is a sequel to the acuteform we have just described. With an attack of acute laminitis that defiestreatment, and does not end in resolution in from ten days to a fortnight, then the chronic form may be expected. 

The brittle horn, convex sole, and other changes we have described underPumiced Foot may, however, be regarded as a chronic laminitis, and thiscondition, as we have already indicated in Chapter VI. , may run a courseslow and insidious from the onset. 

_Symptoms_. --When the disease arises without previous acute symptoms, thefirst thing noticeable is an alteration in the gait. The animal begins togo feelingly, especially when first moved out from the stable. Our opinionis asked as to the cause of the lameness, and an inspection is made. Withthe changes in the form of the hoof as yet wanting, we have nothing toguide us, and other causes for the lameness suggest themselves, probablycorns. Evidence of these is not forthcoming, and we in all probabilitywithhold our opinion until a later visit. On the second or a subsequentcall we are perhaps lucky enough to find our patient down. Diagnosis isthen rendered easier. Made to rise, the animal stands in the attitude wehave described as indicative of laminitis. We have him walked and trottedout. The symptoms of tenderness disappear, and the animal soon goes fairlysound. He is, in fact, workable--that is, by anyone who is careless as tothe comfort of his beast. 

When following an acute attack, we have the most marked symptoms of painand distress, somewhat abating after the second or third week. The walk, however, is still painful, and, for a short time after rising from theground, even difficult. 

In short, in both cases we have the horse going on his heels, with a walkthat is painful, and with symptoms of pain that are most apparent whenmoved on after a rest. 

Later, the changes in the form of the hoof begin to appear. It seems tohave lost its elasticity, and is seen to be dry and chippy, and to havebecome denuded of its varnish-like outer covering. 

In addition, it is of largely altered shape. The toe, by reason of theanimal walking on his heels, and by reason of an increased growth of horn, becomes elevated, so that the front of the wall, instead of forming anobtuse angle with the ground, comes to run very nearly horizontal withit. The horn of the heels, as compared with that of the toe, takes on anincreased growth. The same thing we have already indicated as happening atthe toe, though in lesser degree. Taken together, this increased growth ofhorn at the toe and at the heels has the result of lengthening the diameterof the foot from before backwards, the transverse diameter remaining moreor less normal. The hoof thus loses its circular build, and comes toapproach nearer an elongated oval. 

[FIG. 122. --FOOT BADLY DEFORMED AS A RESULT OF CHRONIC LAMINITIS. ]

At this stage, too, the pathological 'ribbing' of the hoof is observable. The outer surface of the wall becomes marked with a series of ridgesencircling the hoof from heel to heel (see Fig. 81, which illustrates amoderate deformity of the hoof occurring after laminitis). In the badlylaminitic hoof, however, this deformity is largely increased, until in somecases the shapeless mass can hardly be likened to a foot at all (see Fig. 122). 

The inferior or solar surface of the foot also offers certain changes forour consideration. The first thing that strikes one is the convexity of thesole. This, as we have already pointed out, is due to descent of the ospedis, and the highest point of the convex portion is that immediately infront of the apex of the frog. Here the horn is sometimes found to be quiteyielding to the finger, is excessively thin, and is more or less granularand inclined to break up under manipulation. As a consequence, any roughuse of the drawing-knife, or an accidental wounding with sharp flints orstones, leads to exposure of the sensitive structures and local gangrene. 

With the horn of the sole thus deteriorated by reason of excessive andcontinued pressure upon the parts secreting it, it is not surprising tofind that, in many cases, actual penetration of it with the os pedisoccurs. It is the anterior portion of the inferior margin of the bone thatmakes its appearance, and shows itself as a small semicircular white ordark gray line on the sole. 

[Illustration: FIG. 123. --SOLAR ASPECT OF FOOT WITH CHRONIC LAMINITIS, SHOWING ITS ABNORMAL OVAL SHAPE FROM BEFORE BACKWARDS, AND THE EXCESS OFHORN GROWING FROM THE WHITE LINE IN THE REGION OF THE TOE. ]

Exposure of the bone is soon followed by its necrosis, in which case thewound takes on an ulcerating character. From it there is a discharge ofpus, black in colour and offensive in smell, and, protruding from theopening, are excessive granulations of the remains of the sensitive sole. 

The 'white line, ' so apparent when a normal foot is cleaned with the knife, can no longer be sharply distinguished from the surrounding horn, while insome cases the horn composing it takes on an abnormal growth at the toe(see Fig. 123). This adds still further to the abnormal lengthening of theantero-posterior diameter of the foot already mentioned. 

In other cases horn in this position is altogether wanting, and in itsplace is a well-defined cavity, into which the blade of a knife can bereadily passed. This cavity is bounded in front by the original wall of thehoof, and is here lined by a degenerated and hypertrophied growth of thehorny laminæ. Posteriorly the cavity is bounded by the front of the ospedis, and is lined by a thin growth of horn secreted by the keratogenousmembrane covering the bone. Superiorly the cavity is quite narrow, and extends to near the lower surface of the coronary cushion, whileinferiorly, at its open portion, it is often 1/2 inch to 1 inch wide. Laterally it extends on each side of the toe to the commencement of thequarters. 

[Illustration: FIG. 124. --LONGITUDINAL SECTION OF A FOOT WITH LAMINITIS OFTHREE WEEKS' STANDING. On the anterior face of the cavity, in front ofthe os pedis, are thickened horny laminæ. Due to the sinking of the bonycolumn, the os pedis has perforated the horny sole. ]

Exploration with a director, or with the blade of a scalpel, removes fromthe opening a dry detritus. This is composed of the solid constituentsof the escaped blood, the dried remains of the inflammatory exudate, andbroken-down fragments of cheesy-looking horn. The size to which the cavitymay sometimes extend is illustrated in Fig. 124. The thickened horny laminæforming the anterior boundary of the cavity are here depicted, togetherwith commencing perforation of the horny sole by the os pedis. It is thiscavity which, when opened at the bottom and discharging its mealy-lookingcontents, is known as seedy-toe, for a further description of which see p. 293. 

The lameness occurring with chronic laminitis does not always persist. Astime goes on the sensitive structures accommodate themselves to the alteredform and conditions of the horny box. In certain situations--namely, wherepressure is greatest--the softer structures become atrophied, and sometimeseven wholly destroyed; while in other positions the changes in form of thehoof tend to increase in size of its interior, with a consequent diminutionof pressure upon, and increased growth of the structures within it. 

_Pathological Anatomy_. --In detailing the changes to be observed in chroniclaminitis, we take up the description where we left it when dealing withthe pathological anatomy of the acute form. The alterations to be metwith are best observed by taking a foot so diseased and making of it twosections--one longitudinal, from before backwards; the other horizontal, and in such a position as to cut the os pedis through at its centre. 

These sections will expose to view the cavity formed by the pouring out ofthe exudate, and its full extent may be noticed by examining the sectionsalternately. Taking the horizontal section first, it will be seen thatthe hollow space extends wholly round the toe, and as far back as thecommencement of the quarters. In the latter position one is able to observelaminæ still in their normal positions and condition. At the toe, however, the horny and secretive laminæ are widely separated, and the space betweenthem filled with a yellow, semi-solid material, the remains of theinflammatory exudate and new horn secreted by the keratogenous membrane. The laminæ, both horny and sensitive, are greatly enlarged. This is ahypertrophy, resulting from the continued effects of the inflammation, andleads in time to the formation of laminæ quite three or four times theirnormal size. It is this hypertrophy of the laminæ and the pressure of theexudate that causes the bulging and increased growth of the horn at the toe(see Fig. 125), and contributes towards the oval formation of the foot wehave mentioned before. 

[Illustration: FIG. 125. --LONGITUDINAL SECTION OF A FOOT WITH LAMINITIS OFSEVERAL YEARS' DURATION. ]

In the longitudinal section the first thing noticeable is the changein position of the bones, more especially in that of the os pedis. Thecircumstances we have mentioned before--pressure of the exudate upon it infront and tension of the perforans on it behind--have caused it to assumea more upright position than is normal, so much so that in a bad case thefront of the bone becomes quite vertical. This vicious direction the otherbones of the digit follow (see Fig. 125). 

Consequent upon the displacement of the bone, the plantar cushion, byreason of the continued pressure thus put upon it, becomes atrophied, whileits hinder half is, as it were, squeezed into taking up a positionmore posterior and higher in the digit than normally it should. Thehorn-secreting papillæ covering its inferior face thus become directedbackwards sooner than downwards, in which way we account in some measurefor the noticeable increase of horn at the heels. 

_Treatment_. --Chronic laminitis is incurable. Treatment must therefore bedirected towards the palliation of such conditions as are present, withthe object of rendering the the animal better able to perform work. Whenperforation of the sole has occurred, with the attendant formation of pusand necrosis of the os pedis, it is doubtful whether treatment of any kindis advisable. There are on record cases of this description, where carefulcuretting of the exposed and necrotic portions and the after application ofantiseptic dressings, held in position by a plate shoe or a leather sole, has been followed by good results, and the animal restored for a time tolabour. In our opinion, however, early slaughter is the most economicalcourse to adopt, and certainly the wisest advice to give to the ordinaryclient. 

When perforation of the sole is absent, and when serious alteration in theshape of the horny box has not occurred, then the most simple treatment isto put the animal straight away to slow work, with the feet protected bysuitable shoes. 

Here, again, the most useful shoe is the Rocker Bar (Fig. 119). The broadweb and deep seating gives ample protection to the convex sole, and withthe ease in distributing his weight that this shoe affords the animal isable to perform slow work on soft lands with some degree of comfort. 

Should the growth of the horn at the toe and at the heels be undulyexcessive, then our attention may be directed towards reducing it to someapproach to the normal. This is accomplished by removing with the rasp andthe knife those portions indicated by the dotted lines in Fig. 127. Here itwill be seen that the bulk of the horn removed is that protruding atthe toe. After this the animal should again be suitably shod. In thisconnection it should be noted that the fact of the animal walking largelyon the heels tends to a forward displacement of the shoe. This must beprevented by providing each heel of the shoe with a clip, after the mannershown in Fig. 128; or, in the case of a bar shoe, supplying it with a clipat the centre of the bar. 

[Illustration: FIG. 126. --DIAGRAM ILLUSTRATING THE ABNORMAL GROWTH OF HORNAT THE TOE AND HEELS OF THE FOOT WITH CHRONIC LAMINITIS. ]

[Illustration: FIG. 127. --THE SAME FOOT AS IN FIG. 126. The dotted linesshow the excess of horn removed preparatory to shoeing. ]

Among other treatments to be noted we may mention one or two to be foundchiefly in Continental works on this subject. 

The method of Gross consists in thinning down with a rasp about 1-1/2inches of the horn of the wall immediately below the coronet, the thinnedportion extending from heel to heel. The groove made is filled withbasilicon ointment, [A] and the coronet stimulated with a cantharidesointment, In this way there is induced to grow from the coronet a new wallof nearly normal dimensions. 

[Footnote A: Basilicon ointment is made by heating together resin 8 parts, beeswax 8 parts, olive oil 8 parts, and lard 6 parts. Allow to cool withoutstirring. ]

By other operators (Bayer, Imminger, Meyer, and Gunther) this treatmenthas been modified by enlarging upon it and removing the whole of theadventitious horn. 

[Illustration: FIG. 128. --THE SHOE WITH HEEL-CLIP. ]

This is done by means of the drawing-knife and the rasp, the ugly-lookingpumiced foot being carefully cut and trimmed until, so far as outwardappearances are concerned, it is perfectly normal. This done, the wholefoot is treated with a suitable hoof ointment, and a shoe applied thataffords protection to the sole without imposing pressure upon it. Theshoe indicated is either an ordinary shoe with an unusually broad andwell-seated web, or the seated Rocker Bar of Broad. With either it is wellto additionally protect the sole by means of a leather or rubber pad andtar stopping, or by using the Huflederkitt described on p. 148. In everycase the nails must be kept well back in order to avoid the weakened anddegenerated horn at the toe, and to take advantage of the greater growth ofhorn at the heels. 

The wisdom of thus removing the whole of the adventitious horn may bequestioned. Although a foot of a nearly normal shape is obtained, it mustbe remembered that the grave alterations within it are unchanged, andthat in certain positions the operation must have carried us nearer thesensitive structures than is advisable. 

All other treatments failing, the operation of neurectomy has been advised. This we do not think wise. One would imagine that, with degenerativeprocesses already going on in the foot, the tendency to gelatinousdegeneration, always to be looked for in neurectomy, would be increased. This, as a matter of fact, is the case, and is borne out by the statementsof those who have tried this method of treatment. In many cases thelameness even is not got rid of. Even where it is, the operation isafterwards followed by a great tendency to stumble, by sloughing of thehoof, or by a marked increase in the adventitious horn, and a consequentgreater deformity of the foot. 

Sooner than risk neurectomy, it seems to us wiser to give a trial to theoperation advocated by M. G. Joly, namely, that of ligaturing one of thedigital arteries on each affected foot. This operation is performed in thesame position as is the higher operation of plantar neurectomy, and may beeither internal or external. The vessel is exposed, and a double ligature, preferably of silk, placed on it. The artery is then divided betweenthe two ligatures. The immediate effect of the operation is to causea considerable diminution in the arterial pressure, and so lessen theintensity of the ostitis in the os pedis. Its consequences are not soserious as those of neurectomy, and it decongests tissues which neurectomycongests. 

In cases related by M. Joly this operation, practised both in conjunctionwith removal of the excess of horn and without it, has resulted in a markedimprovement in the gait, the animal going to work one month after thetreatment, and remaining sound for some time afterwards. 

2. SEEDY-TOE. 

_Definition_. --A defect in the horn of the wall, usually at the toe, butoccurring elsewhere, resulting in loss of its substance in either itsinternal or external layers (see Figs. 129, 130, and 131). 

_Causes_. --The most common factor in the causation of this defect isundoubtedly disease of the sensitive laminæ. We have, in fact, just givenan excellent example of the formation of a seedy-toe in the sections ofthis chapter devoted to laminitis (see pp. 265 and 286). The cavity hereformed by the outpouring of the inflammatory exudate and the separation ofthe sensitive and horny laminæ persists. It becomes filled with thedried remains of the exudate and perverted secretions from the horny andsensitive laminæ (see p. 287). As yet, however, the cavity is closed below, and its existence only surmised. Later, with successive visits to theforge, the layer of solar horn forming its floor is cut away, and thecavity exposed to view. Its mealy-looking contents are removed, and thecase reported by the smith. 

Although occurring in this way with an acute attack of laminitis, it mustbe remembered that seedy-toe may arise without previous noticeable cause. The first intimation the owner has is a report from the forge thatseedy-toe is in existence. To refer to cases so arising a probable cause isfar from easy. At one time it was believed to be due to parasitic infectionof the horn. Others have blamed the pressure of the toe-clip, excessivehammering of the wall, or pressure from nails too large or driven tooclose. Others, again, say that seedy-toe may result from a prick in theforge, from hot-fitting of the shoe, from standing on a dry and sandy soil, or from the use of high calkins on the front shoes. In these cases--caseswith an insidious onset--we are inclined to the opinion that the diseaseof the horn commences from below, and that the sensitive laminæ becomeimplicated later. Holding this view, one must account for the commencingdisease of the horn by giving, as causes, firstly, those factors (as, for instance, alternate excessive dampness and dryness) leading todisintegration of the horn tubules; secondly, the penetrating into andbetween the degenerated tubules of parasitic matter from the ground; and, thirdly, the final breaking up of the horn, and spread of the lesion underthe invasion thus started. 

[Illustration: FIG. 129. --DIAGRAM ILLUSTRATING POSITION OF SEEDY-TOE(INTERNAL). 1, The horn of the wall; 2, the horn of the sole; 3, the cavityof the seedy-toe; 4, the os pedis; 5, the keratogenous membrane. ]

_Symptoms_. --Lameness sometimes attends seedy-toe, and sometimes does not. This is an important point to be carried in mind by the veterinary surgeonwho is accustomed in his practice to have many animals pass through hishands for examination as to soundness. An animal with advanced seedy-toe--acondition constituting serious unsoundness--may walk and trot absolutelysound, and may give no indication, either in the shape of the wall or thecondition of the sole, that anything abnormal is in existence. Later, however, after the veterinary surgeon has passed him, the purchaser lodgesthe complaint that the horse has a bad seedy-toe, which, so he is told, must have been there for some time. In this case, culpable though he mayappear, there is every excuse for the veterinary surgeon. 

Once the cavity is opened at the toe in the neighbourhood of the whiteline, then diagnosis is easy. A blunt piece of wood, the farrier's knife, or a director may be easily passed into it, sometimes as far up asthe coronary cushion (see Fig. 129). Issuing from the opening is seenoccasionally a little inspissated pus; more often, however, the dry, mealy-looking detritus to which we have before referred. This form of thedisease we may term 'Internal Seedy-Toe. ' for, plainly enough, it has hadits origin in chronic inflammatory changes in the keratogenous membrane. 

[Illustration: FIG. 130. --EXTERNAL SEEDY-TOE COMMENCING AT THE PLANTARBORDER OF THE WALL. ]

[Illustration: FIG. 131. --EXTERNAL SEEDY-TOE COMMENCING ON THE ANTERIORFACE OF THE WALL. ]

Disease of the horn and loss of its substance may, however, also commencefrom without. A report on this condition, under the title of 'ExternalSeedy-Toe, ' is to be found in vol. Xxix. Of the _Veterinary Journal_, fromwhich we borrow Figs. 130 and 131. 

In Fig. 130 it will be seen that the disease commences at the plantarsurface of the toe, and extends upwards and inwards. The same conditionmay also appear anywhere between the coronet and the ground, graduallyextending into the substance of the wall, as shown in Fig. 131. Accordingto the writer, Colonel Nunn, the progress of the disease in this lattercase appears to be faster in a downward than in an upward direction. This, however, is more apparent than real, as the rate of growth of the horndownwards detracts from the progress of the disease upwards, although itspreads over the horn at the same rate. 

Before concluding the symptoms, we may again allude to the fact that, although usually occurring at the toe, the same condition may be met within other positions--namely, at either of the quarters. In appearance and inother respects it is identical with that occurring at the toe. 

When the animal is lame and the existence of seedy-toe is surmised, or whenthe cause of the lameness is altogether obscure, a little information mayperhaps be gathered from noting the wear of the shoe. If the animal hasbeen going lame for any length of time as a result of disease in thesensitive laminæ, then the shoe will be greatly thinned at the heels, andthe toe but little worn. 

_Treatment_. --As with diseased structures elsewhere, the most rationaltreatment, when possible, is that of excision. The entire portion of thewall forming the anterior boundary of the cavity is thinned down withthe rasp and afterwards removed with the knife, wholly exposing thehypertrophied, but usually soft layer of horn covering the sensitivestructures. These hypertrophied portions are also removed, and everyparticle of the dust-like detritus cleaned away. After-treatment consistsin dressing the parts with a good hoof ointment, protecting them, ifnecessary, with a pad of tow and a stout bandage. It may be that theremoval of a large portion of the wall may for some time throw the animalout of work. Acting on Colonel Fred Smith's suggestion, this may be avoidedby having made a thin plate of sheet-iron, slightly larger in circumferencethan the portion of horn removed, and shaped to follow the contour of thefoot. This made, it is sunk flush with the wall by hot-fitting it, and keptin position by several small steel screws fixed into the sound horn, justas in the treatment for sand-crack (see p. 174). This will serve theuseful purpose of maintaining in position any dressing that may be thoughtnecessary, of acting as a support to the horn left on each side of theportion removed, and of keeping the exposed structures free from dirt andgrit. 

Practical points to be remembered in fitting plates of this descriptionto the feet are: The plate must never quite reach the shoe, or it willparticipate in the concussion of progression, and so loosen the screws thathold it in place. For the same reason, that portion of the sole adjoiningthe piece of horn removed must have its bearing on the shoe relieved. Thescrews holding the plate should be oiled to prevent rusting, and shouldtake an oblique direction in order to obtain as great a hold as possible onthe wall. 

When excision is deemed unwise or unnecessary, treatment should be directedtowards maintaining the cavity in a state of asepsis. To this end itshould be thoroughly cleaned of its contents, and afterwards dressed withmedicated tow. The ordinary tar and grease stopping is as suitable as any. This, together with the tow, is tightly plugged into the opening and keptin position by a wide-webbed shoe. Instead of the tar stopping and the tow, there may be used with advantage the artificial hoof-horn of Defay (see p. 152). Before using this the cavity should again be thoroughly cleaned out, and should in addition be mopped out with ether. The latter injunction isimportant, as unless the grease is thus first removed, the composition willfail to adhere to the horn. With the cavity thus cleaned and prepared, theartificial horn, melted ready to hand, is poured into it and allowed toset. 

In every case, no matter what else the treatment, the bearing of the hornadjacent to the lesion should be removed from the shoe. 

Whether practising the method of plugging the cavity or that of excision ofthe wall external to it, attempts to quickly obtain a new growth of hornfrom the coronet should be made. To further that, frequent stimulantapplications should be used. Ointment of Biniodide of Mercury 1 in 8, ofCantharides 1 in 8, or the ordinary Oil of Cantharides, either will serve. 

3. KERAPHYLLOCELE. 

_Definition_. --By this term is indicated an enlargement forming on theinner surface of the wall. In shape and extent these enlargements vary. Usually they are rounded and extend from the coronary cushion to the sole, sometimes only as thick as an ordinary goose-quill, at other times reachingthe size of one's finger. Often they are irregular in formation andflattened from side to side. 

[Illustration: FIG. 132. --A PORTION OF THE HORN OF THE WALL AT THE TOEREMOVED IN ORDER TO SHOW A KERAPHYLLOCELE ON ITS INNER SURFACE. ]

_Causes_. --Keraphyllocele is very often a sequel to the changes occurringat the toe in laminitis. Probably, however, the most common cause is aninjury upon, or a crack through, the wall. It may thus occur from excessivehammering of the foot, from violent kicking against a wall or the stablefittings, and from the injury to the coronet known as 'tread. ' It may alsooccur as a sequel to complicated sand-crack, and to chronic corn. 

That fissures in the wall are undoubtedly a cause has been placed on recordby the late Professor Walley, who noticed the appearance of these hornygrowths following upon the operation of grooving the wall. [A]

[Footnote A: _Journal of Comparative Pathology and Therapeutics_, vol. Iii, p. 170. ]

This gentleman had a large Clydesdale horse under his care for a badsand-crack in front of the near hind-foot, and, as the lamenesswas extreme, he adopted his usual method of treatment--viz. , rest, fomentations, poulticing, and the making of the V-shaped section throughthe wall, and subsequently the application of an appropriate bar shoeto the foot, and repeated blisters to the coronet. In a short time thelameness passed off, and the horse was put to work. A few days later theanimal met with an accident, and was killed. 

On examining a section of the hoof it was found that a vertical horny ridgecorresponding to the external fissure had been formed on the internalsurface of the wall, and that a well-marked cicatrix extended upwardsthrough the structure of the hoof at the part forming the cutigeral groove;furthermore, _a similar ingrowth had been taking place in the line of theoblique incisions made for the relief of the sand-crack_. 

This case has an important bearing on the operation of grooving the wall, which operation we have several times in this work advocated for the reliefof other diseases. It teaches us that the incisions should not be carriedso completely through the horn as to interfere with and irritate thesensitive laminæ, and so set up the chronic inflammatory condition leadingto hypertrophy of the horn. 

From the position on the os pedis of the indentation made in it by thekeraphyllocele (see Fig. 133) it has been argued that pressure of thetoe-clip is a cause of the new growth. This, we should say, cannot be avery strong factor in the causation, for, while we admit that the continualpressure of the clip, and the heavy hammering that sometimes fits it intoposition, is likely to set up a chronic inflammatory condition of thesensitive laminæ in that region, we must still point out that the rarityof keraphyllocele, as compared with the fact that clips are on every shoe, does not allow of the argument carrying any great weight. 

_Symptoms_. --Except under certain conditions this defect is difficultof detection. As a rule, lameness is not produced by it. In making thatstatement we are led largely by the conclusion arrived at by ProfessorWalley. This observer noted the fact that ingrowths of horn such as we aredescribing nearly always take place in false quarter, or after a sand-crackhas been repaired, and that they commonly occur after the operation ofgrooving the wall in the manner we have just shown. 

Now, we know that quite often under these circumstances the horse goesperfectly sound. Thus, while we know that in all probability keraphylloceleis in existence, we have ocular demonstration that the animal is quiteunaffected by it. 

In some cases, however, lameness is present. During the early stages ofthe growth's formation it is but slight, increasing as the keraphylloceleenlarges. Should this be the case, other symptoms present themselves. The coronet is hot, and tender to the touch, sometimes even perceptiblyswollen, and percussion over the wail is met with flinching on the partof the animal. In other cases one is led to suspect the condition bythe prominence of the horn of the wall of the toe. This is distinctlyridge-like from the coronet to the ground, while on either side of it thequarters appear to have sunk to less than their normal dimensions. Webelieve this to be an illusion, as a ridge of any size at the toe readilygives one the impression of atrophy behind it, without this lattercondition being actually present. 

Should this ridge-like formation and the accompanying symptoms of pain andlameness occur after repair of a sand-crack, then keraphyllocele may, withtolerable certainty, be diagnosed. When these outward signs are wanting, however, and the true nature of our case is a matter of mere conjecture, apositive diagnosis may still be made at a later stage--that is, when theabnormal growth of horn reaches the sole. In this case either there ismet with when paring the sole a small portion of horn, circular in form, distinctly harder than normal, and indenting in a semicircular fashion thefront of the white line at the toe, or solution of continuity between thetumour and the edge of the sole and the os pedis takes place, and thelameness resulting from the ingress of dirt and grit thus allowed drawsattention to the case. 

_Pathological Anatomy_. --With the sensitive structures removed from thehoof by maceration or other means, these growths are at once apparent. Theymay occur in any position, but are usually seen at the toe, and they mayextend from the coronary cushion to the sole, or they may occupy onlythe lower or the upper half of the wall. In places the tumour (or 'hornypillar' as the Germans term it) is roughened by offshoots from it, and doesnot always exhibit the smooth surface depicted in Fig. 132. Commonly, thehorn composing the new growth is hard and dense. Sometimes, however, it issoft to the knife, and is then found to be itself fistulous in character, a distinct cavity running up its centre, from which issues a black andoffensive pus. 

In a few cases the sensitive laminæ in the immediate neighbourhood arefound to be enlarged, but in the majority of cases atrophy is the conditionto be observed. Not only are the sensitive structures found to be shrunkenand absorbed, but the atrophy and absorption extends even to the boneitself (see Fig. 133). This latter is a result of the continued pressure ofthe horny growth, in a well-marked case ending in a sharply-defined groovein the os pedis in which the keraphyllocele rests. The fact that the softerstructures, and even the bone, thus accommodate themselves to the alteredconditions is, no doubt, the reason that lameness in many of these cases isabsent. 

_Treatment_. --It is doubtful whether anything satisfactory can berecommended. When we have suspected this condition ourselves, it has beenour practice to groove the hoof on either side of the toe, after the mannerillustrated in Fig. 120, and, at the same time, point-firing the coronetand applying a smart cantharides blister. Certainly, after this operation, lameness has often disappeared--whether, however, as a result of thetreatment adopted or by reason of the structures within accommodatingthemselves to the condition, we would not care to say. 

[Illustration: FIG. 133. --OS PEDIS SHOWING THE GROOVE IN IT CAUSED BYATROPHY AND ABSORPTION INDUCED BY PRESSURE OF A KERAPHYLLOCELE. ]

Other writers advocate the removal of that portion of the wall to which thetumour is attached, after the manner described on p. 182, and illustratedin Fig. 98. This, however, should be a last resource, and should be adoptedonly when weighty reasons, such as excessive and otherwise incurablelameness, appear to demand it. 

4. KERATOMA. 

In our nomenclature the terms 'Keratoma' and 'Keraphyllocele' are both usedto indicate the condition we have just described. There are some, however, who reserve the term 'Keratoma' for horny tumours occurring only on thesole, and for that reason we draw special attention to the word here. Keratoma may thus be used to describe what we have called keraphylloceledirectly that growth makes its appearance at the sole, and is there ableto be cut with the knife. Similar hard and condensed growths may, however, make their appearance on the sole in other positions quite removed from thewhite line, plainly being secreted by the villous tissue of the sensitivesole, and having no connection whatever with the sensitive laminæ. They appear as circular patches, varying in size from a shilling to atwo-shilling piece. Compared with the surrounding horn, they stand outwhite and glistening, while in structure they are dense and hard, andoffer a certain amount of resistance to the knife. They are of quite minorimportance, and, beyond keeping them well pared down, need no attention. Keratoma probably offers us the best analogy we have to corn of the humansubject. 

5. THRUSH. 

_Definition_. --A disease of the frog characterized by a discharge from itof a black and offensive pus, and accompanied by more or less wasting ofthe organ. 

_Causes_. --The primary cause of this affection is doubtless the infectionof the horn, and later the sensitive structures, with matter from theground. Those factors, therefore, leading to deterioration of the horn, andso exposing it to infection, may be considered here. Such will be changesfrom excessive dampness to dryness, or _vice versâ_; work upon hard andstony roads; prolonged standing in the accumulated wet and filth ofinsanitary stables, or long standing upon a bedding which, although dry, isof unsuitable material. 

In this latter connection may be mentioned the harm resulting from the useof certain varieties of moss litter. This we find pointed out by J. RoalfeCox, F. R. C. V. S. [A] Tenderness in the foot was first noticed, and, onexamination, the horn of the sole and of the frog was found to bepeculiarly softened. It afforded a yielding sensation to the finger, notunlike that which is imparted by indiarubber, and on cutting the alteredhorn it was almost as easily sliced as cheese-rind. The outer surfacebeing in this way slightly pared off, the deeper substance of the horn wasdiscoloured by a pinkish stain. The horn of the frog was in many instancesfound detaching from the vascular surface, which was very disposed to takeon a diseased action, somewhat allied to canker, and became extremelydifficult to treat. 

[Footnote A: _Veterinary Journal_, vol. Xvi. , p. 243. ]

Conditions such as these, although not constituting the disease itself, certainly lay the frog open to infection, especially if afterwards theanimal is called upon to work in the mud of the streets of a large town, orto stand in a badly drained and damp stable. 

A further cause of thrush is to be found in the condition of the frog, brought about by contraction of the heels (see p. 118). We have alreadyseen that one of the most prominent factors in the causation of contractionis the removal of the frog from the ground by shoeing, with its consequentdiminution in size and deterioration in quality of horn. This leads tofissures in the horny covering, and favours infection of the sensitivestructures beneath. Thrush is, in fact, nearly always present in the laterstages of contracted foot. 

By some thrush is believed to be but the commencement of canker. With this, however, we do not hold. We believe both to be due to specific causes asyet undiscovered, but that the cause of thrush is not the one operating incanker. In arriving at this conclusion we are guided by clinical evidence. The two conditions are quite dissimilar, even in appearance, and, whileone is readily amenable to treatment, the other is just as obstinatelyresistant. 

_Symptoms_. --The symptoms of thrush are always very evident. Probably thefirst thing that draws one's attention to it is the stench of the puriformdischarge. The foot is then picked up and the characteristic putrescentmatter found to be accumulated in the median, and often in the lateral, lacunæ. The organ is wasted and fissured, the horn in the depths of thelacunæ softened and easily detachable, and portions of the sensitive frogoften laid bare. 

With a bad thrush lameness is present, the frog itself is tender topressure, and often there is considerable heat and tenderness of the heelsand the coronet immediately above. More especially is this noticeable aftera journey. 

It is, perhaps, more common in the hind-feet than in the fore, and moreoften met with in heavy draught animals than in nags. The hind-feet are, ofcourse, more open to infection by reason of their being constantly calledupon to stand in the animal discharges in the rear of stable standings, while it is a well-known fact that heavy animals have their stables keptfar less clean, and their feet less assiduously cared for, than do animalsof a lighter type. 

In a nag-horse with thrush of both fore-feet lameness becomes sometimesvery great. The gait when first moved out from the stable is feelingand suggestive of corns, while progress on a road with loose stones issometimes positively dangerous to the driver. 

_Treatment_. --When this condition has arisen, as it often does, from wantof counter-pressure of the frog with the ground, this pressure must berestored after the manner described when dealing with the treatment ofcontracted foot (see p. 125) either by the use of tip or bar shoes, or bysuitable pads and stopping. 

So far as direct treatment of the lesion itself is concerned, the firststep is to carefully trim away all diseased horn and freely open up thelacunæ in which the discharge has accumulated. Good results are then oftenarrived at by poulticing, afterwards followed up by suitable antisepticdressings. With us a favourite one is the Sol. Hydrarg. Perchlor. Of Tuson, used without dilution. Others use a dry dressing, and dust with Calomel, with a mixture of Sulphate of Copper, Sulphate of Zinc and Alum, or withSubacetate of Copper and Tannin. 

With restoration, so far as is possible, of the frog functions, and withcareful dressing, a cure is nearly always obtained. 

6. CANKER. 

_Definition_. --Under this unscientific, yet expressive term, is indicated achronic diseased condition of the keratogenous membrane, commencing alwaysat the frog, and slowly extending to the sole and wall, characterized by aloss of normal function of the horn secreting cells, and the discharge of aserous exudate in the place of normal horn. 

_Causes_. --The exact cause of canker has still to be discovered. Therefore, before expressing an opinion as to what the _probable_ cause may be, we maystate here that such opinion can only be based upon clinical observation. Such being the case, we are almost duty bound to give the views of olderauthors before those of more modern writers. 

From the mass of material ready to hand we may select the following asserving our purpose. 

The earliest opinion appears to have been that canker, as the nameindicates, was of a cancerous or cancroid nature. This was also believed byHurtrel D'Arboval, who looked upon canker as carcinoma of the recticularstructure of the foot. The same theory we find enunciated in the_Veterinary Journal_ so late as 1890. Although the word 'cancer' or'carcinoma' is not there used, the author employs the terms 'Papilloma' and'Epithelioma' with the evident intention of expressing his belief in themalignant nature of the disease. 

Another early opinion was that the disease was a _spreading ulcer_, gradually extending and changing the tissues which it invaded. 

A further early theory, and one which if not still believed in, has died ahard death, is the constitutional theory. This was believed in by nearlyall the older writers, and is mentioned so late as 1872 by the lateProfessor Williams. In his 'Principles and Practice of Veterinary Surgery, 'he says: 'Canker is a constitutional disease due to a cachexia or habitof body, grossness of constitution, and lymphatic temperament. ' This, webelieve, is credited to-day by some, and yet, quite 100 years before thedate of the 1872 edition of Williams's work--in 1756, to be exact--we finda veterinary writer when talking of grease (a disease, by-the-by, veryclosely allied to canker) exclaiming against this habit of referringeverything which we do not rightly understand to some ill-humour of thebody. The wisdom his words contain justifies us in giving them mentionhere. 'It is a very foolish and absurd Notion, ' he says, 'to imagine aHorse full of Humours when he happens to be troubled with the Grease. Butsuch Shallow Reasoning will always abound while Peoples' Judgments arealways superficial. Therefore, to convince such unthinking Folks, let themtake a thick Stick and beat a Horse soundly upon his Legs so that theybruise them in several Places, after which they will swell, I dare say, and yet be in no danger of Greasing. Now, pray, what were these offendingHumours doing before the Bruises given by the Stick?'

At the present day it is safe to assert that neither the ulcerative, thecancerous, nor the constitutional theory is believed in widely, and, amongthe mass of contrary opinions as to the cause of this disease, we may findthat even quite early many of the older writers had discarded them. 

Quoting from Zundel, we may say that Dupuy in 1827 considered canker asa hypertrophy of the fibres of the hoof, admitting at the same time thatthese fibres were softened by an altered secretion; while Mercier in 1841stated that canker was nothing more than a chronic inflammation of thereticular tissue of the foot, characterized by diseased secretions of thisapparatus. 

Saving that they make no mention of a likely specific cause, these last twostatements express all that we believe to-day. As early as 1851, however, the existence of a specific cause was hinted at by Blaine in his'Veterinary Art. ' We find him here describing canker as a _fungoid_excrescence, exuding a thin and offensive discharge, which _inoculates_ thesoft parts within its reach, particularly the sensitive frog and sole, anddestroys their connections with the horny covering. 

The use of the word 'fungoid, ' and particularly that of 'inoculate, ' issuggestive enough, and is evidence sufficient that either Blaine or hiseditor recognised, simply through clinical observation, the working of aspecial cause. 

Four years later, Bouley is found holding the opinion that canker wasclosely allied to tetter, thus recognising for it a local specific cause. The same observer also pointed out that the secretion of the keratogenousmembrane instead of being suspended was greatly increased, taking care toexplain, as did Dupuy, that the products of the secretion were pervertedand had lost their normal ability to become transformed into compact horn. 

In 1864 this slowly growing recognition of a specific cause receivedfurther impetus from the statements of Megnier. This observer claimed tohave discovered in the cankerous secretions the existence of a vegetableparasite (namely, a cryptogam, as in favus), which he termed thekeraphyton, or parasitic plant of the horn. 

Modern research, though failing to substitute anything more definite, hasnot confirmed this. The exact and exciting cause of canker is thereforestill an open question, and a matter for research. We may, however, sum thematter up by briefly discussing the causes, so far as clinical observationteaches us. This we shall do under two headings--namely, _Predisposing_ and_Exciting_. 

_Predisposing Causes_. --Starting with the assumption that the disease isdue to local infection, we may relate as predisposing causes anythinghaving a prejudicial effect upon the horn, disintegrating it, and so layingthe tissues beneath open to attack. The most prominent in this connectionis certainly a continued dampness of the material on which the animalhas to stand. Particularly is this the case when the material is alsoexcessively foul and dirty, contaminated with the animal discharges, andpresumably swarming with the lower forms of animal and plant life. Weshall therefore find bad cases of canker in stables where the "sets" areirregular, or where no paving at all is attempted, where the drainageis defective, and where darkness and want of proper ventilation favoursorganismal growth. The fact that with modern drainage and a generalhygienic improvement in stabling, canker has to a large extent died out, supports this contention. 

Again, as with thrush, anything removing the counter-pressure of the frogwith the ground and throwing that organ out of play, may be looked uponas a predisposing cause. The atrophy of the frog thus occurring, thedeterioration in the quality of its horn and the fissures in its surfacelay it specially open to infection. That one of the principal factors inthe treatment of canker is a restoration of ground-pressure to the frog andthe sole is sufficient proof of this. 

Further, it is well to note that, although playing no part in the actualcausation, certain constitutional conditions may in some measure predisposethe foot to attack. Clinical observation teaches us that animals of alymphatic nature, with thick skins and an abundance of hair, with flat feetand thick, fleshy frogs, are far more liable to attack than are animalswith reverse points. 

_Exciting Causes_. Those who give this subject careful consideration cannotfail to arrive at the conclusion that canker is most certainly due to localinfection with a specific poison, and that poison a germicidal one from theground. The symptoms arising may be due to the action of a single germ, orto two or more germs acting in conjunction. As to whether the parasiticinvasion is single or multiple we cannot feel certain, but that it _is_parasitic we feel absolutely assured. 

It is simply the light that bacteriological advance has made during thelast two decades that enables us to make the statement with such feelingsof assurance. We arrive at our conclusions by reasoning from analogy. Here we have a disease always exhibiting the same symptoms, more or lesspeculiar to one class of animal, always with a similar characteristicappearance and smell, always obstinately refractory to treatment, showingalways a tendency to spread to the other feet of the same animal, and oftento the feet of other animals _near enough to become_ infected, and alwayscured--when cured it is--by a treatment which may be summed up in two wordsas 'rigid antisepsis. ' Other diseases, with points in common with this, have been directly proved to be due to a specific cause. Common regard forlogic compels us to admit the same for canker. 

[Illustration: FIG. 134. --A FOOT, THE SUBJECT OF CANKER, SHOWINGDESTRUCTION OF THE HORNY FROG, AND A FUNGOID-LOOKING HYPERTROPHY OF THETISSUES BENEATH. ]

_Symptoms and Pathological Anatomy_. --The symptoms of canker are seldomnoticeable at the commencement of an attack. The disease is slow in itsprogress; for some time confines its ravages to the sub-horny tissuesunseen, and is quite unattended with pain. It is not observed, therefore, until considerable damage has been done, and the disease is far advanced. What is usually first seen is a peculiar softening and raising of the hornof the frog. The infective material has set up a chronic inflammation ofthe keratogenous membrane, leading to abnormal secretion, and, in place ofthe horny cells it should normally secrete, is thrown out an abundance of aserous fluid. 

This upraised and softened horn once thrown off is not again renewed, andthe whole of the sensitive frog and perhaps a portion of the sensitive soleis left uncovered. In place of the normal horn, however, is often found ahypertrophy of the elements of the keratogenous membrane leading to hugefungoid-looking growths with a papillomatous aspect, damp in appearance andoffensive in smell, and readily bleeding when injured (see Fig. 131). 

The horn immediately surrounding the lesion is loose and non-adherent tothe sensitive structures. This indicates, of course, that the disease hasspread further beneath the horny covering than is at first sight apparent. Portions of this loose horn removed reveal beneath it a caseous foetidmatter, easily removed by scraping (the perverted secretion of thekeratogenous membrane). When this is carefully scraped away, the sensitivestructures appear to be covered with a thin, smooth membrane, gray incolour and almost transparent, while beneath it may be seen the redappearance of normal sensitive structures. 

If the horn surrounding the lesion is not touched with the knife, butlittle is seen of the extent of the disease, for that removed by naturalmeans is often very small in quantity. To all intents and purposes thedisease appears to be confined to the frog. This appearance is misleading, especially if the disease has been in existence for some time, for itmay have easily spread to the whole of the sole, and even to the greaterportions of the laminæ secreting the wall. 

It is, in fact, not until the pressure exerted by the normal hornis removed by its breaking away that the vascular structures of thekeratogenous membrane begin to swell, and the perverted secretions toenlarge in size. Once the pressure is removed, however, this quicklycomes about, and the characteristic fungoid growths rapidly make theirappearance. 

This tendency to spread is highly indicative of canker. The serous matterexuding from the diseased keratogenous membrane appears, in fact, to behighly infective. Once its flow is commenced, it slowly, but surely, invades the sensitive structures near it, appearing, as Elaine has put it, to 'inoculate' them. What is really the case, of course, is not that thedischarge itself is infective, but that it is contaminated with infectivematerial. 

The fungoid-looking growths to which we have before referred are, inreality, nothing more than the villi of the sensitive frog and sole greatlyhypertrophied and irregular in shape. At times the hypertrophy is as a hugeand compact enlargement occupying the position of the frog. Sometimes, however, it occurs as numerous elongated and twisted fibrous bundles, separated from each other by deep clefts, and the clefts filled with theoffensive cankerous discharge (see Fig. 134). 

[Illustration: FIG. 135. --LOWER ASPECT OF CANKERED FOOT, SHOWINGDESTRUCTION OF WALL. ]

At a very advanced stage canker leads to destruction of much of the hornysole and frog; or even parts of the wall may become separated from thetissues beneath, and break away from the foot (see Fig. 135). At othertimes the disease brings about a deformity of the whole of the foot. Itslongitudinal and transverse diameters become enormously increased, and thewhole foot apparently flattened from above to below (see Fig. 136). Thisindicates that not only has the horny sole been entirely destroyed, butthat the destructive process has also extended to the greater part of thelower half of the wall, with a consequent hypertrophy of exposed softstructures, and a sinking of the bony column, similar to that which occursin laminitis, but not so pronounced. 

[Illustration: FIG. 136. --FOOT WITH ADVANCED CANKER. ]

A further aspect of the badly-cankered foot is to be found in an apparentlyenormous increase in the length of the wall. This we have seen protrudingfor quite 5 inches beyond the plane of the sole. It simply indicates that, in order to keep the animal at work, the smith has at every shoeing sparedthe wall, so that the diseased structures might be kept from contact withthe ground. 

As we have said before, pain and other symptoms of distress are quiteabsent. Animals affected with canker for a long time maintain theircondition, feed well, and are quite capable of performing work underordinary conditions. 

_Differential Diagnosis and Prognosis_. --Perhaps the only disease withwhich canker may be confounded is thrush. They should, however, be easilydistinguishable. The discharge from thrush is not so profuse, and isthicker and darker in colour, while the loosening of the horn is almostentirely absent. Furthermore, thrush shows no tendency to spread, and, evenwhen left untreated, may remain confined to the frog for months, and evenyears. Canker, on the other hand, is slowly progressive, and soon shows thecharacteristic fungoid excresences, which growths are in thrush never seen. A further point of difference is discovered when treatment is commenced. Canker is found to be refractory to a point that is absolutelydisheartening, while thrush, with careful attention, is soon got underhand, and a permanent cure effected. 

The prognosis must be guarded. By many canker has been said to beincurable. This, however, has been clearly shown to be wrong. When theanimal is young, and treatment may reasonably be judged to be economical, then a favourable prognosis may be indulged in, provided the veterinarysurgeon intends to put into that treatment a more than ordinary amount ofindividual care and attendance. Even then, however, he will have to be verylargely guided by the condition of his case. He should see that it isnot too far advanced, and that a great deformity of the hoof, or actualexploration, does not indicate disease of the greater part of the wall. 

_Treatment_. --From what has gone before, it will be seen that theeradication of canker is no easy task, that it is, in fact, a mostdifficult matter, and one not to be lightly undertaken. At the risk ofrecapitulating what we have said before, we may mention here the two pointswhich the veterinarian must bear in mind. (1) That there is no actualdisease or alteration in structure of the deep layers of the keratogenousapparatus. It is only the superficial, or horn-secreting, layer thatconcerns us. (2) That the disease of this superficial layer is infectionwith a material that may reasonably be presumed to be infective. 

Put thus, treatment of canker would at first sight appear to be easy. Onewould imagine that a simple and long-continued soaking of the entire footin a strong enough antiseptic would be all that was needed. Clinicalobservation, however, shows that this is not so, and for this there must bereasons. 

The reasons are these: (1) Between us and the diseased layer upon which ourattention must be directed is often a layer of normal horn, effectuallyprotecting the tissues beneath from any dressing which we might considerbeneficial. (2) Anything applied with the object of destroying septicmaterial, but strong enough, or caustic enough, to injure the membrane uponwhich we are working, only makes the case worse. The superficial layer ofthe keratogenous membrane in which we have judged the disease to exist is, after all, but a delicate structure. When attacked by the application oftoo potent a drug its horn-secreting layer is easily destroyed, and thus, although we may succeed in establishing asepsis, we cannot expect at thepoint of injury a growth of horn. In its place we are confronted with largeoutgrowths of inflammatory fibrous tissue. (3) Shedding of the diseasedhorn and removal of the pressure exerted by the hoof faces us withhypertrophy of the exposed villi. The difficulty of meeting this with anadequate and evenly-distributed pressure is well enough known, and we findin that a further reason that the treatment of canker is superlativelydifficult. (4) The material on which the animal has to stand is a distinctbar to the maintaining of a strict asepsis. 

When we have said this, it is easy to understand that canker is not to besuccessfully met with any so-called specific--that it makes but littledifference what the application may be so long as it is antiseptic, and isused by a man thoroughly conversant with the difficulties he has to contendwith, and with his mind firmly set upon surmounting them. 

With this point established, we will not devote more of our space to aconsideration of the various dressings that have at different times beenhighly advocated in the treatment of the disease. It is interesting, however, to note that intensely irritating and caustic applications havebeen greatly in favour. Nitric acid, sulphuric acid (either alone or itsaction reduced by the addition of alcohol, oil, or turpentine), arsenic, butter of antimony, creasote, chromic acid, carbolic acid, arsenite ofsoda, and the actual cautery, have all been used. 

Without dwelling further on that, we may say at once that a correcttreatment consists in (1) the removal of all horn overlying infectedportions of the keratogenous membrane, (2) the application of an antisepticnot too powerfully caustic in its action, (3) frequent changes of thedressings in order to insure a maintenance of antisepsis, and (4) theapplication of an adequate pressure to the exposed soft structures. Thuscombated, canker is curable. 

The man who, at the expense of much time and trouble, has demonstrated thetruth of these axioms is Mr. Malcolm, of Birmingham. The determination withwhich he clung to his point that canker was, with correct treatment, inevery case curable, was some years ago provocative of much discussion inveterinary circles. That he was successful in proving his contention ismore to our point here. It is his method of treatment, therefore, that weshall give, and this we shall do by liberal extracts from Mr. Malcolm's ownwritings. 

'On the first occasion of operating upon and dressing the cankered foot, it is usually necessary to cast the horse, and this may have to be doneat intervals for a second or even third time; but in most cases once issufficient, subsequent dressing being usually accomplished without muchdifficulty, frequently even without the aid of a twitch. After the horsehas been secured, the drawing-knife is first employed; and if the frogalone is affected, it is unnecessary even to pare the sole, the removal ofall frog horn not intimately adherent to its secreting surface being allthat is required. But if both sole and frog be involved, the whole of thesound horn should be first thinned until it springs under the thumb, and then, using a sharp knife, every particle of diseased horn must becarefully removed from both sole and frog, a process much more easily, andwith far greater certainty, secured by the previous thinning of the horn. 

'The removal of diseased horn should always commence at the most dependentpart of the foot, so that any hæmorrhage produced may be below the partsstill to be operated on, a matter of considerable moment for effectivetreatment. But with due care there will be little hæmorrhage, as, except inthe initial stage, there is no real union between the diseased horn and thediseased vascular secreting surface. 

'After all apparently diseased horn has been removed by the knife, anystill remaining should be at once destroyed by the actual cautery, bywhich it can be identified. All the diseased secreting surface should be_carefully scraped with a thin hot iron_, [A] fungoid growths excised andcauterized, and, indeed, every particle of cankered tissue should, ifpossible, be eradicated. In securing this more reliance can be placed onthe actual cautery than on any other, whether liquid or solid: it is moreunder control in application, more decisive in effect, and its results canbe anticipated with a far greater certainty. Moreover, its aid in diagnosisis of immense value; applied to the thinned horn or secreting surface itunmistakably demonstrates the presence or absence of canker. Healthy tissuechars black; cankered tissue, on the contrary, bubbles up white under thehot iron, and presents an appearance not unlike roasted cheese. 

'Although this test is certain for horn thinned to the quick, it is not tobe relied upon with thick horn, the outside of which may be practicallyhealthy and char black, while its underlying surface may be cankered. Withthis exception the test is an infallible one, as by it the demarcationbetween cankered and healthy tissue can be clearly traced, and as a resultwe can with equal confidence radically _remove_[A] all cankered tissue, andconserve all healthy. As the object of that abominably cruel and barbarousoperation of stripping the sole is the exposure of all canker, and as thiscan be done with equal certainty with the aid of the hot iron, there can beno necessity for performing it. The pain of cauterizing cankered tissue, which is a necessary operation, is infinitesimal (canker largely destroyingsensation), compared with the pain produced in the totally unnecessaryprocess of tearing healthy horn from a highly sensitive tissue. 

[Footnote A: The words in italics are alterations in the original articlemade by Mr. Malcolm in a private letter to the author (H. C. K. ). ]

'Having by means of the knife and cautery removed every known particle ofdisease, the next procedure is to pack the surface of the sole and frogthus exposed with a _mild dressing, such as vaseline; but if the cankeredsurface has not been efficiently, scraped, than there is required a more_[A] powerful astringent or caustic dressing, which may vary considerablyaccording to the individual fancy. A great favourite of mine consists ofequal parts of sulphates of copper, iron, and zinc, mixed with strongcarbolic acid, a very little vaseline being added to give the masscohesion. The dressing, covered by a pledget of tow, is held in positionby a shoe with an iron or leather sole, and the dressing and tow togethershould be of sufficient bulk to produce slight pressure on the sole whenthe nails of the shoe are drawn up. This insures contact between thedressing and the exposed surface, as well as any benefit derivable frompressure. 

[Footnote A: The words in italics are alterations in the original articlemade by Mr. Malcolm in a private letter to the author (H. C. E. ). ]

'The dressing of the foot and nailing of the shoe can usually be moreexpeditiously performed when the horse is on his feet than when prone. Ifonly the frog, or the frog and a small part of the sole, be involved, thehorse should be kept at work, but if a large part or the whole of the solea few days' rest may be necessary; but as soon as the condition of the footwill allow, work should be resumed, and it is simply marvellous how sound ahorse will walk while minus the greater part of his sole from canker. 

'On the second day following the shoe should be removed, and the footredressed. To effect this it is necessary to recast the horse. Commencingat the edge of the sound horn, at the most dependent part of the foot, all new horn, no matter what its condition, must be pared to the quick, especial care being taken to effectually remove any lingering disease. Wantof success is frequently attributable to neglect of this precaution. A small particle of canker remains undetected, forms a new centre ofinfection, and just when success is anticipated, much to your chagrin youhave to deal with a fresh outbreak of canker, instead of a rapidly-healingfoot. Parenthetically, I may here remark that the amount of more or lessimperfect new horn produced by a cankered surface after an effective butnot too destructive cauterization is almost incredible, and one cannot failto be struck with the very active proliferation here compared with themeagre production of new horn by the healthy surface. 

'After all disease has been excised, carefully clean the foot with waste, thoroughly protect any raw surface resulting from overcauterization by somemild agent, such as a saturated calomel ointment, reapply an astringentdressing over the whole affected surface, and nail on the shoe. This methodof procedure should now be thoroughly carried out daily for a time, andas it is proceeded with a successful issue soon becomes assured in nearlyevery case. Where, in spite of these efforts, the disease still persists, depend upon it the fault is with the operator, who has failed to eradicatesome centre of infection. Under these circumstances it may be necessaryto recast the patient, repare the foot, and by the aid of eye, knife, and cautery, endeavour to find the cause, and having found it, which caninvariably be done, remove it. The usual treatment will then speedilybecome successful. As the case proceeds dressing every other day willsoon be sufficient, then twice a week, and finally, once a week untilsufficiently cured. 

'During this healing process, and after the complete eradication of cankerit may be again repeated, no agent seems to have a more beneficial effectthan calomel, and for this purpose it is best used as a dry powder. Underthis dressing any remaining spot of canker is readily detected by the wetcondition of the calomel when the shoe is removed the next day. In dealingwith such a spot, a very good plan, after all apparently diseased tissuehas been excised, is to touch the cankered part with solid nitrate ofsilver, or a feather dipped in one of the strong mineral acids, andthen reapply calomel over the surface. The result of this treatment isfrequently very gratifying. 

'In successful treatment the shoe must be removed each time--an adjustableplate will not do, as no man can thoroughly pare and examine a foot withthe shoe on, and imperfect dressings are worse than useless. Indeed, it isbetter not to pare or thin the horn at all, than to imperfectly pare, sincecanker, if undestroyed, develops far more rapidly under thin horn thanunder thick. 

'In conclusion, I would again urge the necessity, at the very firstoperation, when the horse is down, of removing _every single particle_ ofthe diseased tissue, either by excision or effectual cauterization, but atthe same time taking very great care to guard against the latter beingtoo destructive. The cautery should be laid aside as soon as the tissuecauterized ceases to _burn white_. The moment at which the canker hasthus been eradicated without destroying sound tissue is indicated bythe appearance of healthy horn, by the intimate union of that with thesecreting surface, and by the healthy aspect of the exuded blood whenparing has been carried to the quick. 

'Should subjacent healthy structures be destroyed during the process, that is shown by the production of a raw sore, or of a sore to which a"sit-fast, " coextensive to the injury, is firmly attached. This seriouslyretards recovery. The secreting surface having been destroyed, no new horncan be produced directly from the part, and a new secreting surface and newhorn have now to grow inwards from the surrounding undestroyed tissue, andthat is a slow process. At the same time, on the principle of choosingthe least of two evils, practical experience teaches that it is better toproduce a small sore or a "sit-fast" than to leave a part of the cankerundetected; but, on the other hand, it is better to leave a small partof canker undetected, which can be recognised and removed at the nextexamination, than to cause a large slough. The object of the skilfulsurgeon is, naturally, to avoid both extremes; and if trouble be taken tocarry out the procedure described, there need be no fear of the result. '[A]

[Footnote A: _Journal of Comparative Pathology and Therapeutics_, vol. Iv. , p. 24. ]

Treated in this way, the horse with cankered feet may be usually kept atwork during the whole time that treatment is carried out, and a cure isobtainable in periods varying from six weeks to six or even twelve months. 

The same essentials in treatment--namely, removal of diseased horn, antiseptic dressings, and pressure--are insisted on by other writers. Bermbach, [A] in 1888, treats canker as follows: The horse having been cast, the undermined hoof-horn is removed with the knife, and the hypertrophiedsensitive structures, if necessary, reduced in the same manner. The chiefdifficulty in removing the latter is experienced in the lateral lacunæ ofthe frog, where it is most conveniently scraped away with a spoon or sharpcurette. Professors Hoffmann and Imminger also operate in the same way, applying an Esmarch's hæmostatic bandage, and using the knife and curettefreely. [B]

[Footnote A: _Ibid_. , vol. Ii. , p. 68. ]

[Footnote B: _Veterinary Journal_, vol. Xxxv. , p. 433. ]

Hæmorrhage is afterwards arrested, and a dressing of perchloride of mercury(a solution, 1/2 per cent. , in equal parts of alcohol and water) applied. The after-dressings succeeding best are those of _slightly_ caustic andastringent agents, preferably in the form of a powder, and held in positionby carbol-jute pads and linen bandages applied with a certain amount ofpressure. 

The same author draws attention to the fact that caustic agents such asnitrate of lead, chloride of zinc, etc. , act too powerfully if the bleedinghas been arrested and the wound disinfected. They then form a thick crust, under which profuse suppuration takes place. The same agents are likewisecontra-indicated when hæmorrhage is still present. In this latter casethey combine with the blood to form metallic albuminates, which lie as animpenetrable layer on the surface of the wound, and so hinder the action ofdrugs on the tissue below. 

During his after-treatment, Bermbach advocates removal of the dressingsevery second day, all cheesy material to be scraped away with the knife, and the sublimate lotion to be used again. He also insists on the animalbeing kept standing in a _dry stable_, --nothing but a stone pavement keptclean--and put to regular work in a plate shoe after the first or secondweek. Cure of advanced cases is said to be obtainable in from four to sixweeks. 

As illustrative of the value of pressure in the treatment of canker, we mayalso draw attention to a treatment advocated by Lieutenant Rose. [A] Thisobserver holds that adequate pressure is unobtainable by packing the foot, and, to obtain it, removes the wall from heel to heel, much after themanner of preparing the foot for the Charlier shoe, so that the _whole_ ofthe weight is taken by the sole and the frog. Tar and tow is then lightlyapplied, the foot placed in a boot, and the patient turned into aloose-box. The dressing is repeated at intervals of four or five days untilthe animal is cured. 

[Footnote A: _Veterinary Record_, vol. Xi. , p. 435. ]

Those who have followed this method of treatment have modified it byactually shoeing the animal Charlier fashion, and keeping him at work, attention, of course, being at the same time given to a proper antisepticdressing. 

_Reported Cases_. --1. (Malcolm's Treatment[A]). The subject was a five-yearold horse belonging to a client of Mr. Giver's, of Tamworth. The case wasan exceptionally bad one, for not only was the whole of the frog and soleof the near hind-foot cankered, but the disease on the outside quarterextended to within 1/2 inch of the coronet, and on the inside quarter towithin 2 inches of it. As the owner, a farmer, had not proper conveniencefor Mr. Olver to treat the case, the latter asked me, while visiting him, if I would care to undertake the treatment, saying at the time it wouldbe a very good test-case, as the disease was so far advanced. I readilyagreed, and, after the necessary arrangements, had the horse removed toBirmingham on July 2. In this case it was found necessary to cast theanimal and cauterize the foot a second time before a healthy granulatingsurface was secured; but after this the progress towards recovery wasuninterrupted, although necessarily slow, on account of the large amount ofnew secreting surface which had to be formed. 

[Footnote A: _Journal of Comparative Pathology and Therapeutics_, vol. V. , p. 48. ]

The horse was finally discharged, after inspection by Mr. Olver, absolutelycured and free from canker, on January 7. 

The illustration (Fig. 135, p. 312) is from a photograph, and it gives asomewhat imperfect representation of the state of the foot two months afterit came under my care. 

2. (Rose's Treatment. [A]) This was a bad case of canker, which had been fortwo or three months treated in the ordinary manner, with but little signof ultimate success. Commenced in June and carried on until the end ofSeptember, the ordinary treatment consisted in burning down the fungusgrowth with the hot iron, and dressing with copper sulphate, zinc sulphate, and boracic acid. The cauterization was repeated every five days. 

[Footnote A: _Veterinary Record_, vol. Xi. , p. 435. ]

The treatment of Lieutenant Rose was commenced at about the end ofSeptember, at which date the disease extended from the toe on one side ofthe foot right back to the heel, involving the sole, half of the frog, andthe bulb of the heel. One week after treatment the diseased surface wasdrier, and granulations were more healthy. At the expiration of a fortnightthe new horn had commenced to grow from the wall, and also from the frog, right round the diseased surface, the diseased part of the bulb of the heelbeing divided from the sole by new horn. 

Three to four weeks later the diseased surface was gradually gettingsmaller, while in about six weeks it was quite healed up, the last place toheal being a strip outside the bar, between it and the wall, and a smallerspot on the bulb of the heel. These healed up simultaneously, and left theanimal sound. 

3. (Treatment by Pressure, H. Leeney [A]). I was consulted in the earlypart of last summer, before the dry weather had begun, as to a farm-horsewith canker in three feet. Her shoes were in the 'disgruntle' condition weso often find on farms, that, to give her a level bearing until I shouldcall another day with a farrier to help me to pack the foot up in theold-fashioned way, I had the remaining shoes pulled off. The case somehowdropped out of my list, and I neglected to call, until asked one day to seesomething else. 

[Footnote A: _Veterinary Records_, vol. Xi. , p. 447]

I then found that, under a pressure of work, the animal had been used inthe shafts of a farm-cart on tolerably level ground, and when the dryweather had already set in. There was a distinct improvement in all thediseased feet, and as she was badly wanted I contented myself with raspingoff some broken crust, and supplied some caustic dressing for use at night. Without shoes she worked continuously on the dry and hard meadow-land forseveral weeks, and was practically cured in something less than threemonths. My astringent or caustic lotion may have had something to do withthe cure of the deep-seated parts, but the bare recital of the case shouldbe sufficient to show that it is all a question of bearing, or nearly so. 

7. SPECIFIC CORONITIS. 

_Definition_. --In describing this condition under the above heading, weare following the lead of Mr. Malcolm. We may define it as a chronicinflammatory condition of the keratogenous membrane, usually confined tothat of the coronary cushion, the ergots and the chestnuts, but sometimesextending to that of the frog and the sole, characterized by a malsecretionof the affected membrane similar to that observed in canker. 

_Causes_. --The cause which we have indicated for canker--namely, a localspecific one, is in all probability the one operating here. Apparentlythere is a variance of opinion as to whether the condition is actuallycanker or not. We think, however, that the character of the secretion ofthe affected membranes, the appearance of the growths, the manner in whichthey react to the hot iron, the comparative absence of pain, and otherpoints of similarity, point to the fact that the two conditions areactually identical. In other words, the cause is precisely the same, andthe only point of difference is the alteration in the point of attack. 

_Symptoms_. --Like canker, the disease is insidious in onset. In preciselysimilar manner the horn, and in this case the skin of the coronet, isunderrun. Later there is the partial shedding and fissuring of theundermined horn and the exuding of the characteristic discharge--in thiscase not so watery as that of canker. The caseous material of canker isalso present, as is a disposition to hypertrophy of the exposed sensitivestructures. What horn is left becomes rough and irregularly fissured, andhas been likened by some observers to deeply-wrinkled bark of an old tree. A peculiar characteristic of this condition is the state of the ergots andchestnuts. Here the keratogenous membrane participates in the diseasedprocess, and their horn becomes dry and brittle, and readily splits intosmall fibrous bundles very similar to the fibroid growth described incanker. These excrescences are easily separated from the sensitivestructures beneath, and the exposed surface is seen to be more or lessmoist, or even exhibiting a slight oozing of blood. 

Again, as in canker, the deeper layers of the sensitive structures appearto be normal, the horn-secreting layers being the only ones affected. According to Malcolm, the disease is in its nature equally as inveterate ascanker, but it is easier to treat, on account of its more exposed position. 

_Treatment_. --This is exactly that as described for canker. 

[Illustration: FIG. 137. --SPECIFIC CORONITIS OF ALL FOUR FEET. ]

[Illustration: FIG. 138. --OFF FORE-FOOT AFFECTED WITH SPECIFIC CORONITIS. ]

_Recorded Case_. --The subject of this case was a young black cart gelding. The disease is reported as having begun as thrush, and then extended to thecoronet. When I saw him he had been in a similar condition to that depictedin Fig. 137 for, it was said, two or three months, the driver of the horsemeanwhile endeavouring to effect a cure by some potent drug of his own. Theanimal was in good condition, but walked with difficulty owing to the pain. The coronary bands were swollen to two or three times their natural size, and this caused the hair immediately above to curl upwards. Just below thecoronary bands there was a line of separation between them and the wall. They themselves were covered with the cheesy substance typical of canker, and they bled on friction. Down the wall of the off fore-foot some bloodhad trickled, which may be seen in Fig. 138. The frogs of all four feetbulged backwards, and were badly affected. The soles were covered withnormal horn, but I did not resort to paring to see if they were affected. One very curious feature about the case was the fact that all thecallosities (ergots and chestnuts) seemed to participate in the morbidprocess, and they, too, were covered with a thin layer of soft cheesy horn. The animal used to bite at his coronets and also the callosities above theknees and hocks until they bled, which they did quite easily. The ownerwould not go to the expense of having him treated, so he was destroyed. [A]

[Footnote A: Henry Taylor, _Veterinary Record_, vol. Xvii. , p. 311. ]

CHAPTER X

DISEASES OF THE LATERAL CARTILAGES

A. WOUNDS OF THE CARTILAGES. 

To a consideration of this we shall devote but little space. It issufficient to say that any wound in the region of the coronet should alwaysbe given the most careful attention. More particularly should this be sowhen it is ascertained that the wound has involved one of the lateralcartilages. Wounds of non-vascular bodies such as these are always slow toheal, and, by reason of their slowness, invite septic infection. In manycases, in fact, it happens that they do not heal at all. Instead, theinjured part becomes necrotic, is unable to cast itself off, and remains asa centre of infection in the depths of the wound, thus constituting what isknown as a quittor. 

Apart from this, it will be remembered that the internal face of thecartilage is in intimate contact with the pedal articulation, especiallyanteriorly. Wounds in this situation are, therefore, likely to penetratethe joint, giving us as a complication of the injury the conditions ofsynovitis and arthritis. 

Immediately a wound is inflicted in this position, attempts should be madeto insure thorough asepsis of the part. When possible, by far the betterway of accomplishing this will be to wholly immerse the foot in a tub ofcold antiseptic solution, and keep it there for an hour three times daily. During the time the foot is out of the solution the wound should beprotected with a pad of carbolized tow or other suitable dressing, andwrapped in a linen bandage or clean bag. If unable to use the bath, thenantiseptic solutions of more than moderate strength should be freelyapplied to the wound and the adjacent parts, a carbolized or otherantiseptic pad placed over it, and the bandage adjusted as before. Repeatedinjuries to the cartilages, even if not attended with an actual wound, are apt to bring about their ossification and end in the formation ofside-bones. 

B. QUITTOR. 

_Definition_. --A fistulous wound of the foot, usually opening at thecoronet, and variously complicated according to the structures invaded byits contained pus. For the reason that quittor is in every-day veterinarynomenclature _usually_ associated with necrosis or other abnormal conditionof the lateral cartilage, we include its description in this chapter. 

_Classification_. --It has been customary with Continental authors toclassify quittor according to the extent and position of the diseasedprocess. There were thus distinguished:

_(a)_ The _Simple_ or _Cutaneous Quittor_, in which had occurred nothingmore than necrosis of a portion of the coronary skin and the structuresimmediately underlying it--that is, the superficial portion of the coronarycushion. 

_(b)_ The _Tendinous Quittor_, in which not only the immediatelysubcutaneous tissues were attacked, but also portions of tendon and ofligament. 

_(c)_ The _Sub-horny Quittor_, in which the diseased process had invadedthe deeper portions of the coronary cushion, and continued a downwardcourse until the laminal tissue below the upper margin of the wall wasinvolved, or any other case, no matter what the starting-point, in whichpus existed within the horny box and was discharging itself by a fistulousopening. 

_(d)_ The _Cartilaginous Quittor_, in which a portion of the lateralcartilage had become attacked and rendered necrotic. 

We believe that--in this country, at any rate--the word 'quittor' isusually held to indicate one or other of the two latter conditions, andprobably the last of these; and that the two first are held of smallaccount, or hardly of sufficient gravity to allow of the word 'quittor'being applied to them. In fact, by defining quittor as a 'fistula, ' orlittle pipe, we have ourselves already indirectly restricted the use of theword to the two latter conditions, for in those varieties known as Simpleor Cutaneous and Tendinous, the wound is generally broad and open, or, at any rate, superficial, and can scarcely be strictly described as'fistulous. ' In the two latter, however, a true fistula exists. These, however, have only one essential difference, and that consists simply inthe position of the lesion and the structures it has attacked. In the mainthe symptoms will be the same, the disease in each case about equallyserious, and in each the same essentials of treatment will have to beregarded. 

In our opinion, therefore, a lengthy classification serves no useful end, and we think matters will be simplified by considering quittor undertwo headings only--namely, 'Simple or Cutaneous' and 'Sub-horny, ' anddiscussing the other varieties as simply complications of either of thesetwo. 

1. SIMPLE OR CUTANEOUS QUITTOR. 

_Definition_. --This condition is simply a sloughing of a portion of theskin of the coronet, together with a portion of the immediately underlyingsoft structures. 

_Causes_. --This form of quittor has its origin more often than not incontusions, punctures, or wounds of the region severe enough to cause deathof a small portion of the tissues. In this case the low vitality of theparts does not allow of the dead portion being removed piecemeal by aprocess of phagacytosis, as is usually the case with similar injurieselsewhere. Instead, the tissues around, aided by a process of suppuration, cast the offending portion off as a slough. It is the wound remaining afterthe slough which we may really regard as a quittor. In this connection maybe considered as causes blows from falling shafts, self-inflicted treads, or treads from other horses, overreach, etc. On the other hand, simple orcutaneous quittor may occur without ascertainable cause. In this case wecan only explain its appearance, as we did that of simple coronitis (see p. 231), by attributing it to septic infection through a wound or a blow thatis able to inoculate the skin, yet which is insufficient to cause pain, orin any other way attract the attendant's notice. Meanwhile, the spot ofinfection thus started spreads, and the end result is an abscess in thecoronary region, again accompanied with necrosis and sloughing of more orless skin and other tissue, which terminates by discharging its contentsand leaving behind a wound which again constitutes a cutaneous quittor. Thus, as with simple coronitis, anything lowering the vitality of theparts, and so favouring infection of the skin, may bring about a quittor. Walking through much water in the winter months, through the dirt and mudof our streets, through melting ice and snow, or through anything in thenature of a chemical irritant, may be looked upon as a cause. 

_Symptoms_. --Whether commencing from an ascertainable injury, or beginningat first unnoticed, cutaneous quittor is characterized sooner or later bythe appearance of an inflammatory swelling, usually confined to the seat ofinjury. Heat and tenderness are present, and the animal is lame. 

Later the inflammatory swelling becomes more profuse, the animal isfevered, and the symptoms of lameness increased. Poulticing is at thisstage perhaps resorted to. By its means the process of suppuration isaided, and the swelling (at first tense and hard) either becomes graduallysoftened, its contents discharged, and a simple abscess cavity left behind, or the suppuration runs immediately round the necrosed structures, andcasts them off bodily as a slough. This latter condition is alwaysmanifested, where the hair does not hide it, by the colour of the skin. Atfirst this is only red in colour--the angry red of an inflamed spot. As itsintention to slough away becomes evident, the red gradually gives way to agray, or even blue-black appearance, while from around it oozes a slightdischarge of pus, yellow in colour and non-offensive, or blood-stained anddark in appearance, and foetid to the smell. 

Almost invariably these symptoms are added to by a more or less diffuse andoedematous swelling of the lower portion of the limb, extending in somecases to as high as the fetlock or the upper third of the cannon. 

With the casting off of the slough the phenomena of inflammation to a greatextent subside, the pain ceases, and the case under ordinary conditionscommences to mend. 

_Pathological Anatomy_. --In its early stages the condition of simple orcutaneous quittor is really a condition of acute coronitis (see p. 229), and consists in an inflammation of the subcutaneous tissue, and the moresuperficial portions of the coronary cushion. The tissues implicated aredestroyed outright, become infiltrated with the inflammatory exudate andescaped blood, and act as a source of irritation to the still livingtissues around. Under the irritation the latter, as we have said before, cast the necrosed portion away by a process of sloughing. 

Always, however, it is found that the portion to be sloughed off, whileeasily separated from the tissues adjacent to its sides, is closelyconnected on its lowermost or deeper face with the structures below, andcannot be torn away without hæmorrhage and the causing of acute pain. 

_Prognosis_. --With wounds about the feet our forecast should always beguarded. Even with this, the most simple form of quittor, no decidedopinion should be given until the progress of the case warrants one inreasonably assuming that complications are absent. Once this point isdecided, a favourable prognosis may be given. 

_Complications_. --With cutaneous quittor various complications may arise, according to the extent of the invasion of the septic matter. Necrosis oftendon, of ligament, or of cartilage, caries of the bone, or a condition ofsynovitis and arthritis may be met with. As these complications are equallycommon to sub-horny quittor, we shall reserve their description untildealing with that condition. _Treatment (Preventive)_. --Immediately afterthe infliction of an injury in this position, more especially if it is suchas to lead one to judge that necrosis will follow to any large extent, thepatient should be rested. Ill effects may then be probably warded off byhaving the foot immersed in a cold antiseptic solution, and afterwardsbound with an antiseptic pad and bandage. 

_Curative_. --When the condition has gone undiscovered until commencingnecrosis and suppuration are plainly discernible, then the wisest course wecan follow is to do all we can to hasten removal of the necrosed portion. 

This is best done by promoting the suppurative process by means of warmthor stimulant applications. 

To this end hot poultices, or, better still, hot baths, should be resortedto. Under their influence a greater supply of blood is directed to thestill healthy tissues enabling them to actively continue the inflammatoryprocesses necessary to the detaching of the portion necrosed, while, atthe same time, the pus organisms, stimulated by the heat, are stirred intogreater activity, and the readier accomplish their purpose of destroyingthe adhesion still existing between the necrotic portion and thesurrounding living tissues. 

When prolonged poulticing or bathing cannot be practised, then the swellingshould be stimulated with a sharp cantharides blister, repeated, if thecase demands it, at intervals of a few days. 

Should the swelling show distinct signs of pointing, and an abscess isplainly the condition to be dealt with, its contents should be liberated bya free use of the knife. In this connection it is important to insist onthe fact that the opening should be made large enough. One bold incisionfrom the uppermost limit of the swelling down to the coronary margin of thewall is usually sufficient. 

Even when pointing is not very evident, and suppuration is plainly more orless diffuse, benefit may still be derived from the use of the knife. Inthis case a deep scarification of the part is indicated. Three, four, ormore vertical incisions are made in the swelling, and from them obtained aflow of blood mingled with a small quantity of pus from several differentcentres. By this means sloughing of the diseased portion is quicklyobtained, and nothing but an ordinary open wound left for treatment. Itshould be mentioned, however, that when sloughing can be in any way inducedto take place naturally it is better to allow this to take place. Even whenthe necrosed portion is freely movable, and only adherent by its base, itshould not be forcibly removed, but left to the slower but more effectualaction of the tissue reactions. If torn forcibly away, we in allprobability leave in the bottom of the wound remnants of the dead tissue, which, being small and consequently less productive of inflammatoryphenomena, are not so readily sloughed as the larger portion. These remainas centres of infection, and prolong the case. 

Once a suitable slough has occurred, the after-treatment is simple. Itconsists in dressing the wound with reliable antiseptics, and maintainingthe parts in a healthy condition until Nature completes the cure byrepairing the breach. Solutions of carbolic acid, of perchloride ofmercury, of zinc chloride, or of moderately strong solutions of coppersulphate, are all of them useful (see also treatment of coronitis on p. 236). 

It is sometimes found that even with careful attention the wound leftby the removal of the slough shows a marked disinclination to heal. Thegreater portion of the cavity becomes filled with granulation tissue, andthe epidermis gradually closes round until all is covered except a spot ofperhaps the size of half a crown or a crown piece. Here the regenerativeprocess stops, and the wound obstinately refuses to effectually close. 

In such cases we have derived excellent results with the actual cautery. The animal is cast, the foot firmly secured by fastening it upon the cannonof another limb, and the animal chloroformed. A practical point to beremembered in this connection is that all necessary fixing of the limb iseasier performed if the chloroform is administered first. With the patientthus secured we first of all ascertain by means of the probe whether or nothe non-healing of the wound is due to the presence of a fistula. Decidedin the negative, we take an ordinary flat firing-iron, and with it cut awaya portion of the skin immediately around the still open wound, carryingour incisions deep enough to 'scoop' out a large portion of the newinflammatory tissue beneath. With the loss of pressure from beneath, occasioned by the removal of so much of the cicatricial tissue, theepidermis the more readily closes over the wound. To a large extent alsothis new growth of epidermis is helped by the renewal of the inflammatoryphenomena brought into being with the cauterization. 

2. SUB-HORNY QUITTOR. 

_Definition_. --A fistulous wound of the foot in which the lower and blindend of the fistula is situated below the level of the coronary margin ofthe wall. 

_Causes_. --These, again, will be practically the same as those mentionedin the cause of cutaneous quittor--namely, bruises, punctures, wounds--infact, any injury upon the coronet severe enough to cause death of tissueand a suppurating wound. We may thus expect sub-horny quittor to followupon treads, overreach, accidental injuries with the stable-fork, and kicksfrom other animals. 

Sub-horny quittor may also arise without original injury at all to thecoronet. Either from a violent blow upon the hoof, or from the animalhimself kicking violently against a wall, death of a portion of thesensitive structures takes place within the hoof, suppuration ensues, andthe formation of quittor commences. With the escape of the pus at thecoronet the quittor is fully formed. 

Any other diseased condition of the foot in which suppuration is presentmay in like manner terminate in quittor. In complicated sand-crack, suppurating corn, or in ordinary pricked foot quittor may be a sequel. Inthese conditions the pus formation either goes unnoticed or is neglected, and after seriously invading the sensitive structures within the hoof, breaks out at the coronet. Again, too, as with the simpler form of quittor, and as with coronitis, we may always regard as a predisposing cause theaction of excessive cold in promoting septic infection of the wound whenoccurring at the coronet. 

_Symptoms and Diagnosis_. --Where the fistulous wound has had itsstarting-point in an injury to the coronet diagnosis is, of course, easy. The history of the case explains it. Nothing in this instance remains butto probe the opening, and ascertain its direction, depth, and extent. 

An animal with the wound thus open at the coronet, and freely dischargingits contents, may, if no serious complications exist, walk tolerably sound. It is only when put to the trot that symptoms of lameness are apparent. 

It may so happen, however, that we first see the case when the symptoms arewholly those arising from a painful suppuration within the horny box. This occurs when the original injury has taken place at a more dependentposition than the coronet. Either from violent blows upon the hoof, puncture from below, from corn or from sand-crack, or any other causes wehave enumerated, suppuration is occurring deeply within the hoof, with asyet no opening upon the coronet. 

Even when an opening has already occurred on the coronet, the samecondition of sub-horny suppuration may be met with in cases when theopening of the fistula has by some means or other become occluded. Granulation tissue, for instance, may have temporarily closed the mouth ofthe fistula. The pus, instead of continuing its discharge thereat, is madeto burrow in other directions. 

In either of these cases pain is excessive, the animal walks on three legs, the foot is painful to percussion, and grave constitutional disturbanceis noticeable. The presence of pus is immediately suspected, and, in theabsence of any indication of an opening having existed at the coronet, searched for at the sole. It may or may not be found. If found it is givenexit, and the case ends as one of ordinary pricked foot, of suppuratingcorn, or some other condition equally simple when compared with quittor. In those cases where the pus is not discovered at the sole, one adopts theexpectant treatment of poulticing. This, if pus is present, is followedby a painful swelling of the coronet. At one point there forms a hot andtender enlargement, with the hairs on it standing straight up from theskin, which latter is seen below red and inflamed in appearance. 

Later, the abscess--for abscess it is--discharges its contents, the openingis explored, and we find that in extent it is not confined to the coronaryregion, but that it is deep enough to constitute a true sub-horny quittor. 

This discharge of the abscess contents may take place at a well-definedspot on the coronet, or it may ooze out at the junction of the wallwith the skin. In appearance the discharged pus varies. When the softerstructures only are attacked it is thick, and yellow or white in colour;when bone is involved it is ichorous; and when attacking the horn itselfblack or gray. It may or may not be extremely foetid, and often it ismingled with blood. 

When evidence of a previous opening upon the coronet is plain, then it isnot considered wise to attempt a paring of the sole. Instead, poulticingis at once resorted to, to induce the discharge of the pus through itsoriginal channel. Once this has occurred a fistulous wound remains, whichis open for treatment upon one or other of the lines we shall afterwardsindicate. 

COMPLICATIONS--_(a) Necrosis of the Lateral Cartilage_. --This is theso-called 'cartilaginous quittor' of other writers. In all probability itis the condition generally understood when the word 'quittor' is used byone practitioner to the other. Its tendency to keep the disease existing ina chronic form renders it of grave importance, and for that reason we giveit first mention among the complications. 

It may occur as a sequel either of cutaneous or of sub-horny quittor, andmay result either from actual wounding and infection of the cartilage, orfrom an attack on it of septic matter originating elsewhere. 

Unless there has been discovered a fistula, which on probing is seen tolead direct to the position in which we know the cartilage to be, weknow of no precise means by which the existence of this condition may bediagnosed. When free from other complications, the horse with his foot inthis state may travel fairly sound. This is so when the necrosis is situatein the posterior half of the cartilage, in which case the irritation set upby the disease is confined to the comparatively non-sensitive tissues ofthe cartilage itself and the fibrous mass of the plantar cushion. Whenattacking the anterior half of the cartilage, the close contiguity of thejoint renders the disease of a more serious nature. It is then that we haveacute pain, and with it extreme lameness, for in this position it is morethan likely that we have involved either the synovial membrane of thearticulation or the tops of the sensitive laminæ. It will be rememberedthat here the synovial membrane protrudes as a small sac between theantero- and postero-lateral ligaments of the joint. More or less easilythen it is bound to come into intimate contact with the septic matterattending the necrosis of the cartilage, and so share in the inflammatoryprocesses, afterwards communicating them to the interior of thearticulation. 

With necrosis of the lateral cartilage is always swelling and thickening ofthe skin and subcutaneous structures of the coronet. This is the greaterthe longer the disease has been in existence. Upon the swelling is seen themouth of the fistula, or it may be the mouths of several, and from them alla discharge of pus. 

The mouth of each fistula is generally filled with a mulberry-likegranulation tissue, standing above the level of the skin, and bleedingeasily if touched. The exuding pus is thin and pale gray in appearance, gritty to the touch, and generally free from pronounced smell. At othertimes its colour is reddened with contained blood, and floating in it aretiny particles of a pale-green substance, which when picked up and rubbedbetween the fingers are seen to be small fragments of the diseasedcartilage. 

Should the mouth of a fistula become occluded with the granulations fillingit, and the discharge prevented from escaping, it soon happens that we haveclose to the fistula that has closed a tender fluctuating swelling. Thispoints and breaks, and pus is again discharged from another opening. Inthis manner is accounted for the multiplicity of scars and fistulas seen onthe swelling of an old-standing quittor. 

The continued, inflammation thus kept in existence has the effect ofrendering the skin and subcutaneous tissues in the neighbourhood greatlythickened and indurated. This in time leads to a tumour-like enlargement, and causes the structures of the coronet to greatly overhang the hoof. Atthe same time the constant inflammation has made its stimulant effectsnoted in a great increase in the growth of the horn of the wall. 

Although more abundant, however, the quality of the horn is deteriorated. The perioplic ring has become obliterated, and the varnish-like appearanceof the healthy wall destroyed. Cracks and fissures in its surface arenumerous, and sometimes deep enough to lead to exposure of the sensitivestructures beneath, complicating the quittor with a sand-crack of apeculiarly objectionable type. 

_Pathological Anatomy of the Diseased Cartilage_. --The bulk of observersappear to agree in the statement that in quittor the necrotic cartilage ispea-green in colour, and recognise it by that characteristic. In size thenecrotic portion thus recognisable varies from the tiniest speck to aportion the size of a horse-bean. Commonly, however, it is about as largeonly as a pea. It is seen to be more or less detached from the rest ofthe cartilage, to which it is adherent by one of its extremities only. Ingeneral appearance we can best liken it to the split half of a green pea, whilst others have compared it with the green sprouting of a seed. Theportions of cartilage nearest the necrotic piece are also slightly green incolour, thus indicating that here also the diseased process has commenced. This peculiar change of colour in the affected cartilage is of greatimportance to the surgeon. It enables him when operating to distinguishwith some degree of certainty those portions of the cartilage which arehealthy and those which are not. 

_(b) Necrosis of Tendon and of Ligament_. --This complication of quittoris, as we have said before, treated by other writers as a distinct form ofthe disease, and described by them under the heading of Tendinous Quittor. 

This simply means, of course, that the diseased process has extended toeither of the flexor tendons, to the tendon of the extensor pedis, or, perhaps, to the ligaments of the pedal articulation. 

Of the flexor tendons, the perforans is the one commonly attacked, byreason, of course, of its more superficial position. At times, however, especially when its aponeurotic expansion is diseased, the necrosis of theperforans spreads until the aponeurosis is eaten through and the phalangealsheath penetrated. Septic materials gain entrance thereto, and commence tomultiply. In this way the flexor perforatus is invaded, and comes to sharein the diseased process. 

The extensor pedis is usually attacked by extension of the disease from anecrotic cartilage, or results from the infliction of a severe tread in ahind-foot. In this case the diseased structure has nothing between it andthe articulation, the synovial membrane in one position actually lining itsinner face. The result is that a condition of synovitis is easily set up, and the case aggravated by that and by arthritis. 

With the flexor tendons attacked pain is always very great, and lameness isexcessive. This, however, is not sufficiently characteristic to enable usto determine the precise seat of the necrotic changes. Later, however, atender but hard enlargement made its appearance in the hollow of the heel, which enlargement, later still, became soft and fluctuating. At this stagethere is also considerable swelling along the whole course of the tendons, as high up as the knee or the hock. The foot is carried forward with allthe phalangeal articulations flexed, and in many cases the limb is unableto take weight at all. Manipulated after the manner of examining thetendons for sprain, this swelling is found to be extremely painful. Theanimal flinches from the hand, and shows every sign of acute suffering. This condition may, in fact, be mistaken for sprain, and is only to bedistinguished from it by carefully noting the history of the case--first, the appearance of the swelling in the hollow of the heel, and, secondly, the _after_-swelling of the upper portions of the tendons. 

The formation of the abscess, the after-discharge of its contents, and thefinal establishing of a fistula, are processes greatly prolonged in thisform of quittor. It will readily be understood why this should be so whenone remembers the depth at which the suppurative process is going on, thethickness of the metacarpo-phalangeal sheath, and the resistant nature ofthe material of which this latter is made, and which must be penetratedbefore the condition becomes observable. 

After the opening of the abscess, which usually takes place in the hollowof the heel, there is left the fistulous wound which obstinately refuses toheal. Or it may be, again, that there are several of these fistulas, eachopening in the heel, and the mouth of each marked by a small, ulcer-likeprojection. The discharge continually oozing from these keeps the heelconstantly wet with a thick purulent discharge, which is nearly alwaysblood-stained, and very often foetid. 

This constitutes what is known as tendinous quittor in its worst form, for more often than not there is associated with it inflammation ofthe navicular bursa, caries of the bones, or arthritis of the pedalarticulation. 

With the extensor pedis attacked matters are not quite so grave, in spiteof the fact that the articulation is closely situated thereto, for in thiscase the more superficial position of the diseased structure allows bothof readier exit of the discharges and of easier removal of the necrosedportion and after-treatment of the wound. 

_(c) Caries of the Bones_. --Portions of the os pedis, more especially ofits wings, and therefore usually occurring in conjunction with necrosedcartilage, become carious in quittor. In many cases it is impossible to saywith certainty when this has occurred. In a few instances, however, theexuding discharge gives evidence of what has happened. It is thin, butextremely offensive, with the characteristic odour of decayed bone ortooth, and with a feel that is gritty with contained particles of broken-upbone. If, with a discharge of this nature present, the probe also conveysto the fingers the sensation that bone is reached, then diagnosis may besure. 

_(d) Ossification of the Cartilage_. --This may take place in part or inwhole. It, of course, constitutes Side-bone, a fuller description of whichwill be found in a later portion of this chapter. 

_(e) Penetration of the Articulation_. --This may occur either as a resultof the suppurative changes or as an accident in excision of the diseasedcartilage. Unless it is followed by a severe purulent arthritis, it is notso grave a complication as at first sight it would appear. 

_(f) Synovitis and Arthritis (Purulent)_. --Should this complication arise, the case is a most serious one. Beyond here mentioning the fact that it mayoccur, we shall not dwell on it. Fuller consideration is given to it inChapter XII. 

_Treatment_. --The various treatments adopted for the cure of sub-hornyquittor offer the veterinary surgeon a large number to select from. Wewill describe them in the order in which they are, perhaps, most commonlypractised. 

_Poultices and Hot Baths_. --As in cutaneous quittor, and as in coronitis, when the pus formation is only suspected, and has not yet broken out at thecoronet or elsewhere, then the first indication in treatment is the useof warm poultices or of hot baths. Their application is in most casesproductive of pointing at the coronet. 

Directly this appears it is a wise plan to thin the wall down with the raspimmediately below the swelling. To some extent it relieves the pressure ofthe inflammatory products within, and at the same time paves the way foroperative measures which may be necessary later on. 

With the breaking of the abscess and the discharging of its contents, wemay in some measure ascertain the condition we have to deal with. The probeis used, and the abscess cavity explored. The size of the wound, its depthbelow the upper margin of the wall, the structures involved, and otherinformation, may be thus obtained. 

At first, however, the nature of the wound, and the character of thedischarges, must largely guide us as to the treatment we adopt. In manycases, even where the abscess cavity is far below the upper margin of thewall, and is presumably in an unfit position to drain and heal, a a regularapplication of an astringent and antiseptic dressing is sufficient to bringabout resolution. If, however, the discharge from the wound continues to beliquid, and the wound itself at one spot refuses to heal, it may be judgedthat a portion of necrotic tissue is situated under the wall, and affectingthe laminæ, the cartilage, or ligament, as the case may be. If this is so, then operative measures must be determined on (see Removal of the Wall, p. 349). 

_Blisters_. --Instead of the poultice and hot baths, the pointing of theabscess and the casting off of the slough may be brought about by theapplication of a sharp cantharides blister. We have, in fact, seen manycases where this treatment was adopted prior to the formation of a fistula, and also in cases where one or more fistulous openings already existed, where repeated blisters to the coronet have alone been sufficient to effecta cure. 

We are bound to admit, however, that the treatments of poulticing andblistering are only expectant--we might almost say empirical. At any rate, we admit to ourselves that what we have advised and carried out is not initself curative, but only a means of assisting Nature to satisfactorilywork her own ends. Empirical or not, however, we believe that in everycase of quittor it is wise in practice to at first adopt some such simplemeasure, for in nearly every instance where operative measures arepractised, the patient must be laid aside for at least several weeks, whereas in this way he may be kept at work and a cure effected at the sametime. 

_The Actual Cautery_. --Largely of the same empirical nature, yet doingsomething a little more calculated to destroy necrotic tissue and bringabout its sloughing is the use of the cautery, both actual and potential. 

The actual cautery may be beneficially employed for the relief of sub-hornyquittor in at least two ways. 

In the first place, it is often used--a blunt 'point-firing' iron being theinstrument--instead of the knife as a means of evacuating the contents ofthe coronary abscess. Those who use it for this purpose are able to saythis in its favour: it brings about the opening of the abscess without theunsightly hæmorrhage attending the use of the knife, and at the same timejust as effectually empties it. The opening made is not nearly so likelyto close prematurely--that is, before a proper course of treatment of thewound has been carried out--and so leave necrotic tissue at its bottom. Theintense tissue reaction it sets up is productive of a large slough, castoff by highly active inflammatory phenomena, which means that the remainingwound is one in which no dead tissue is left, and which is more amenable totreatment. 

We have also seen the actual cautery used in sub-horny quittor, where thatdisease has reached a chronic fistulous stage, as a means of cauterizingthe whole length of the lining of each fistulous passage. 

At the present day this method is regarded as barbarous, and savouringtoo largely of the methods and practice of the old empirics. There is nodenying the fact, however, that it is at times followed by a speedy andcomplete cure of what has for months been an intractable and apparentlyincurable quittor; and, honestly speaking, we ourselves can see nothingvery greatly against the operation in certain cases save its appearance. Inthat it is certainly rough, and is not calculated to favourably impress themore critical of our clientele. With the animal chloroformed, however, muchof what can really be urged against it disappears, and on farms and otherplaces where a skilled and competent dressing of an operation wound cannotbe looked for, it is sometimes wise to advise this method of treatment inpreference to more advanced methods of operating. So far as we can judge, the after-effects are very little worse than those following otheroperative measures, more especially when a suitable case has been chosen. 

This method of treatment is particularly applicable to cases of chronicsub-horny quittor in the more posterior parts of the foot. Here, if one ormore fistulas exist, their openings are probed and the direction of thesinuses determined. In all probability they are burrowing down along-sidethe wall to the sole, where, for want of outlet, they are invading thesubstance of the plantar cushion or the plantar aponeurosis. 

Should this preliminary probing demonstrate that neither of the fistulasrun dangerously near the joint, then the operation may be decided on. 

The animal is cast and chloroformed, the foot firmly fixed, and the horn ofthe quarter rasped away quite thin. The sole of the same side is also paredwith the knife until the horn of both the quarter and the sole yieldseasily to pressure of the thumb. All that is then needed is three or fourlong, round, and pointed irons (about 1/4 to 3/8 inch in diameter) heatedto redness. These are inserted into the fistulas, and the false mucous coatof these passages thus destroyed. When the iron, on being directed into thefistulous opening at the coronet, is found to travel alongside the wall, and to easily reach the sole, it should be made to go further still. Thesole is penetrated, and a dependent opening thus made for the escape of thedischarge that afterwards accumulates. 

What happens now, of course, is that an intense and acute inflammationis set up along the whole track of the fistula, in which position theinflammatory changes were heretofore chronic. The whole lining of thefistula, and with it, we hope, all necrotic tissue, is cast as a slough, leaving nothing but healthy tissue behind. This, with a suitable dressing, heals and gives no further trouble. 

The after-treatment consists in the application of hot poultices. Thesetend to greatly ease the pain, and at the same time to facilitate theremoval of the slough. The poulticing should be continued, therefore, untilthe sloughing comes about, which happens, as a rule, at about the fifth orseventh day. 

Immediately the slough is cast off, the poultices may be discontinued anddressing of the wound carried out. This consists of injections of solutionsof zinc chloride 1 in 200, perchloride of mercury 1 in 1, 000, carbolic acid1 in 20, of Villate's solution, or of such other antiseptic as the surgeonmay think fit. The dependent orifice at the sole should be kept open for aslong as possible, being occasionally trimmed round with the drawing-knife, and scooped out with a sharp-edged director. 

Directly a healthy and pink-looking granulation is observed along thetrack of the iron, and the discharge therefrom takes on a thick and yellowappearance, the strength of the antiseptic solutions should be graduallydiminished. This point, in fact, is of great importance in treating allwounds of the foot. There is a great temptation, on account of the knownexcessive liability of the parts to septic infection, to use an antisepticsolution unduly strong. What must be remembered is that used _too_ strongthey themselves give rise to dead tissue, or to impermeable layersconsisting of compounds of the discharges with themselves, and so createsubstances that prove a source of irritation and subsequent trouble. 

_The Potential Cautery_. --This is employed in the treatment of sub-hornyquittor, either in the solid form (in sticks, in lumps, or in the powder), or in the liquid form, when it is injected with a quittor syringe. 

In the former method such drugs as perchloride of mercury in the lump, ornitrate of silver, chloride of zinc, and caustic potash or soda in thestick, are introduced into each of the sinuses present. This is done bymeans of a director or a probe. 

A better method, however, when the dressing lends itself to the purpose, isto use it in the form of a powder, wrapped in the form of small cubesin extremely thin paper, such, for instance, as is used for rollingcigarettes. It is then conveniently inserted into each fistula. Introducedin this more finely divided form the drug is, perhaps, a little more activein bringing about the desired result. 

This method of 'plugging, ' although practised by many, we cannot recommendin preference to the use of the hot iron or of liquid injections. Ourreasons are these: the action of the drug is a protracted one. Almostimmediately after its introduction into the fistula there is formed aboutit an almost impermeable layer of a metallic albuminate, which effectivelyprevents further rapid action of the caustic. In addition to thuspreventing further action of the dressing, this combination of the tissuealbumin with the metal of the salt, together with much necrotic tissue thatit has caused, is extremely hard to remove from the healthy tissues. Thiswe explain by pointing out that the action of the caustic, prolonged asit is, sets up a tissue reaction which partakes largely of the type of achronic rather than an acute inflammation. With a chronic inflammationthere is sooner a tendency to the production of fibrous tissue (and thusthe firmer attachment of the necrosed portions) rather than an activephagocytosis and the casting-off of a slough. Again, careful though we maybe with the probe, it is extremely difficult to be certain that we havediscovered the whole extent of any fistula. An equal difficulty, therefore, exists in being certain that we have placed the caustic in the positionin which it is most wanted--namely, at the furthermost end of the fistulawhere the necrotic tissue is to be found. 

When a caustic is used at all, it is far better to employ it in the liquidform, when either of the drugs we have just mentioned may again be used. Inthe first place, the liquid is far more likely to be brought into contactwith the diseased structures than is the solid salt. Also, its action maybe regulated by altering the strength of the solution, and the liability toform impermeable albuminates thus diminished. 

Probably the best solution for use in this way is the old-fashionedVillate's solution (see p. 199). 

This liquid should be injected at least every day, and, in a bad case, even two or three times daily. Practical hints to be borne in mind whenattempting to cure quittor by means of injections are these:

If the fistulas are numerous, the fluid should be injected into theirvarious orifices. 

In order to force the fluid to the bottom of each diseased track, it isnecessary, when injecting one opening, to firmly close all others. 

Several injections should be made at each time of injection. In otherwords, we must not be content with just forcing fluid in. It must be forcedin, and again forced out by a further syringeful. The fistulous tracksmust, in fact, be washed in the liquid. 

The effect of the injection during the first eight or ten days is to rendersuppuration more abundant and whiter. After two weeks of the treatmentsloughing of the inside of the sinuses occurs, and healing of the woundcommences. Signs that this is occurring are--slight hæmorrhage at the endof each injection, and a gradually increasing difficulty in forcing in thefluid. 

_The Making of Counter-openings to the Fistulas_. --Although Villate'ssolution or any other caustic used in the manner we have describedoften effects a cure, many practitioners insist on the fact that acounter-opening to the fistula must also be made. 

The probe is used and the direction and depth of the fistula ascertained. Through the wall is then made an opening at exactly opposite the lowestpoint found by the probe, or through the sole if the probe should therelead us. This opening is best made with a sharp-pointed iron, and mayafterwards be kept large enough by an occasional trimming with the knife. Many of the older authors, and with them writers of the present day, declare that unless this is done the ordinary injection is likely to failin a great many instances where it would otherwise have been successful. 

Where a counter-opening is thus made it is found that it very readilycloses with granulation tissue, and the purpose for which it was madedefeated. This may be avoided by the use of a seton. In preference to theseton, however, we ourselves would advise that the opening be kept free bythe occasional use of a sharp-edged director or a fine scalpel. 

An interesting modification of the practice of making a counter-opening isthat related by Veterinary-Captain S. M. Smith. [A] In point of severity itruns a middle course between the making of a simple counter-opening andthe removal of a wedge-shaped portion of the coronary band and the wall, amethod which we shall later describe. 

[Footnote A: _Veterinary Record_, vol ii. , p. 157. ]

To perform this operation, the animal is cast and chloroformed. The foot isfixed and the parts thoroughly cleansed. The horn of the wall is then sawedthrough in a direct line from the coronary margin to the solar edge, thesaw-line running exactly over the seat of the sinus. 

A strong scalpel is now introduced at the coronary opening, with itscutting-edge outwards, and is gradually passed down the opening made by thesaw. In this way the sinus is completely destroyed, and from end to endconverted into an open wound. The parts are then washed in a perchloride ofmercury solution, covered with a mixture of powdered iodoform and boracicacid, over which a pledget of carbolized tow is placed, and then a bandageover the whole. This dressing should be left on three or four days, afterwhich the injury should be treated as an ordinary wound. In conclusion, the author says: 'I can safely recommend this line of treatment to anypractitioner having an obstinate case under treatment. '

_Removal of the Wall and Excision of the Necrotic Tissue_. --This wemay term the radical operation for sub-horny quittor, for it is oftenproductive of a successful issue when all other means have failed. Nomatter in what position the sinus is, whether at the extreme anteriorportion of the coronet, or whether in the region of the heels, it is to bethoroughly opened up. To do this, the fistula is carefully explored withthe probe and a knowledge of its exact dimensions arrived at. This iscarefully noted, and the horn of the wall for some little distance aroundit then rasped down quite thin. Immediately over the sinus, and for a shortdistance on either side of it, the horn is stripped away to the sensitivestructures. The cavity of the fistula is then opened up with a scalpel, andevery particle of diseased tissue removed with this instrument and a pairof forceps. After-dressing consists simply in the application of suitableantiseptics. 

_When the Complication of Necrosed Tendon or Ligament exists_. --We may takeit as an axiom that wherever this exists, whether it is in the extensorpedis, in the lateral ligaments of the joint, or in portions of theflexors, all diseased structures should, where possible, be removed. Thisis done either with a scalpel or with a curette. 

When septic matter has gained the sheath of the perforans, and theformation of pus therein is indicated by inflammatory swellings in thehollow of the heel, it is sometimes advisable to lay the sheath open for 1to 2 inches along the course of the tendons. This, if a fistula is present, may be best done with a blunt-pointed bistoury, or with a cannulateddirector and a scalpel. With the pus thus given exit, and an antisepticdressing regularly applied, the case sometimes ends in rapid resolution. More often than not, however, it is found that the pus has been liberatedtoo late, and that it has gravitated in the sheath to the extent ofaffecting the plantar aponeurosis. Or it may be, of course, that it was inthe plantar aponeurosis the disease commenced. Whichever may have been thecase, we have in the hollow of the heel one or more fistulous openings, oran opening we have made ourselves, leading down to a necrosed portion ofthe terminal expansion of the perforans. 

In such cases we ourselves have derived benefit from a regular flushingof the sinuses with a 1 in 2, 000 solution of perchloride of mercury, introduced by means of a glass syringe, followed later by flushing in thesame manner with a 1 in 40 solution of carbolic acid, the hollow of theheel meanwhile being kept clean with an antiseptic pad and bandage, or byliberal applications of an antiseptic powder. 

The septic materials are in this way destroyed, and the wound heals withoutfurther complication. We must admit, however, that the cure of the lesionis generally at the expense of slight lameness, due, in all probability, to inflammatory tissue adhesions between the flexor perforans and theperforatus, and to a partial destruction of the synovial membrane of thesheath. 

If, in spite of the antiseptic irrigations, the fistula persists, thennothing remains but to resort to excision of the aponeurosis, as describedon p. 222. 

_When Necrosis of the Lateral Cartilage is present_. --In this case we mayat first try the ordinary treatments of poulticing; and blistering, ofantiseptic caustic injections, and of plugging. In some cases a cure iseffected. Should these fail, however, and we intend to see the finish ofour case, then operative measures must be determined on. This means cuttingdown upon the diseased cartilage, and either removing the necrosed portion, or excising the cartilage in its entirety. 

The latter method is seldom practised in this country. As it is the mostradical of the two, however, we shall describe it here first. 

_Extirpation of the Lateral Cartilage_. --The operation of extirpating thelateral cartilage is by no means a new one, being introduced, according toZundel, by the senior Lafosse in 1754. It consisted in removing a portionof the wall by grooving and stripping it, and of excising the exposedcartilage by means of a sage-knife. 

As to what portion of, and how much of the horn of, the quarter shouldfirst be removed, and as to what particular direction each groove shouldtake, opinion among the older writers varied considerably. This we knownow is not an important matter, and it is sufficient to say that the firstpreliminary is a thinning down of the horn of the quarter with the raspover the position occupied by the cartilage. At the present time there aretwo or three modifications of the operation as originally introduced. In all, however, the preliminary steps are the same. We shall thereforedescribe them collectively, as applying correctly to either of the threemethods of operating we are about to show. 

_Preparation of the Subject and Preliminary Steps in the Operation_. --Onthe day previous to the operation the horn of the wall immediately over thecartilage must be so thinned with a rasp as to yield readily to pressureof the thumb in any position. It should be so thin as to only just avoidwounding the sensitive structures below. 

The whole of the foot must then be thoroughly cleansed, and rendered asnearly aseptic as possible. The use of warm water, soap, and a stiff brushis the readiest means of removing the surface dirt. Afterwards the footshould be soaked for some time in a reliable antiseptic solution, a 1 in1, 000 solution of perchloride of mercury being the most suitable. Whenremoved from the solution the foot must be packed round with wool ortow impregnated with corrosive sublimate, and then bandaged, the wholeafterwards wrapped in a thick cloth, or protected with a boot. 

On the following day the animal is brought out and cast, and the footdesired to be operated on firmly secured, after the manner described on p. 81. The bandages and sublimate pads are then removed, and the skin ofthe coronet over the seat of operation shaved of hair. An Esmarch rubberbandage is next run up the limb, and the tourniquet applied, thus renderingthe operation a nearly bloodless one. 

This done, the animal is chloroformed, and an antiseptic douche played overthe foot. 

So far, the steps in the operation are common to all methods. There arenow, however, three slightly differing modes of extirpating the cartilage, which modes vary simply according to the structures severed by the knife. 

_First Method_. --This is the oldest method of the three, and consists inmaking (1) a horizontal incision through the sensitive laminæ along thelower border of the cartilage, and (2) a vertical incision through the skinof the coronet, the coronary cushion, and a portion of the sensitive laminæ(see Fig. 139). 

The flaps (Fig. 139, _a, a_) are now held back by tenaculæ, and the wholeof the cartilage, or only the necrosed portion, carefully excised by meansof right- and left-handed sage-knives. Fistulous openings in either of theflaps _a, a_ must now be carefully curetted and dressed, and the flapsallowed to fall into position. They are then sutured with carbolized gut, and the wound finally dressed as to be described later (p. 357). 

[Illustration: FIG. 139. --EXCISION OF THE LATERAL CARTILAGE (OLD METHOD). The wall covering the lateral cartilage first thinned and stripped off; thetwo flaps (_a, a_) of skin and the coronary cushion made by the verticalincision turned back. _a_, The operation flaps; _b_, the exposed cartilage;_c_, the sensitive laminæ; _d_, the coronary cushion. ]

_Second Method (after Holler and Frick_[A]). --These operators deem it wiseto leave untouched the skin of the coronet and the coronary cushion. Theytherefore make their first incision along the lower border of the coronarycushion (see Fig. 140), afterwards exposing the lower half of the cartilageby removing a half-moon-shaped portion of the thinned horn and underlyingsensitive laminæ (see Fig. 140, _b_). 

[Footnote A: Two cases of quittor successfully treated by this method arereported by R. Paine, M. R. C. V. S. , in the _Journal of Comparative Pathologyand Therapeutics_, vol. Xv. , p. 81. ]

[Illustration: FIG. 140. --EXCISION OF THE LATERAL CARTILAGE. (AFTER MOLLERAND FRICK. ) _a_, The thinned horny wall covering the coronary cushion; _b_, the lateral cartilage exposed by stripping off the thinned wall; _c_, thesensitive laminæ. ]

This done, the external face of the cartilage is separated from the skinof the coronet. To do this a double sage-knife is run flatwise between thecoronary cushion and the cartilage, with the convex surface of the bladetowards the skin. The knife is then passed backwards and forwards until thenecessary separation is accomplished. During these movements of the knifea finger of the unoccupied hand should follow the knife, and guard thecoronary cushion against injury. 

Following this, the inner surface of the cartilage must be also separatedfrom the structures lying beneath it. To this end a sage-knife (right- orleft-handed, according as to whether the anterior or posterior portion ofthe cartilage is to be first removed) is again passed into the incision. With the cutting-edge of the knife forward, it is gradually reached roundand under the hindermost end of the cartilage, and theposterior half ofthe cartilage separated from underlying structures, and at the same timeexcised by one clean cut forwards. Using the second sage-knife in a similarmanner, the cutting-edge this time backwards, it is reached in front of thecartilage, whose anterior half is then excised by a careful cut backwards. Any small portions of cartilage remaining after this are sought for withthe finger, and carefully removed by means of a scalpel and a tenaculum. 

The fistulous opening or openings in the skin of the coronet should now bethoroughly curetted, and the whole of the wound dressed as to be describedlater. 

In removing the anterior half of the cartilage it is highly important toremember the close contiguity to it of the synovial membrane of thepedal articulation. This projects as a small sac between the antero- andpostero-lateral ligaments of the joint. Risks of injury to it may bediminished by having the foot secured with a line, and pulled forward by anassistant while the cut is being made. 

_Third Method (after Bayer)_. --This operator recommends that, afterstripping a half-moon-shaped piece of horn from the seat of operation, instead of raising the skin of the coronet and the attached coronarycushion in two flaps (as Fig. 139, a, a), that the cartilage be exposedby raising up one flap only (Fig. 141, a), consisting of a portion ofthe sensitive laminæ, the coronary cushion, and the skin and underlyingstructures of the coronet. 

With the horse cast and the preliminary steps over, the thinned horn ofthe quarter is incised in a semicircular fashion, and the half-moon-shapedpiece thus separated from its surroundings stripped off. At about 1/4 inchfrom the incision in the horn, a second incision of similar shape is madethrough the sensitive structures, which incision is also carried up intothe skin and structures of the coronet. This incision severs, from bottomto the top, (1) the sensitive laminæ covering a portion of the pedal boneand a portion of the lateral cartilage, (2) the coronary cushion, and (3)the skin of the coronet and such structures as lie between it and thecartilage. 

[Illustration: FIG. 141. --EXCISION OF THE LATERAL CARTILAGE. (AFTERBAYER. ) The horny wall is stripped off over the seat of operation. _a_, Semicircular flap of sensitive laminæ, coronary cushion, and skin; _b_, thelateral cartilage; _c_, the sensitive laminæ; _d_, the coronary cushion. ]

That this incision of the sensitive structures should be kept at 1/4 inchfrom the one in the horn has a reason. It is that when this flap is againplaced into position (as later it will have to be) we have round itscircumference a rim of soft structures into which to place the sutures. Andin this connection it is well to advise the operator that the thinness ofthe keratogenous membrane (the laminal portion of it) should warn him thatthe portion of it to be turned up--namely, that forming the tip of theflap--should be _scraped_ away quite close to the os pedis. Unless this isdone, there will not be a sufficient thickness left to afterwards bringinto position and suture. 

The half-moon-shaped piece of tissue incised is now carefully dissectedaway from the external face of the cartilage, until it may be turned up asa flap (see Fig. 141, _a_), and held from off the cartilage by a tenaculum. 

The exposed cartilage is now carefully removed by the aid of a sage-knifeand a stout pair of forceps, the same precaution of holding the foot wellforward being again taken in order to avoid wounding of the articularcapsule. 

At this stage in the operation considerable care is required. The operatormust remember that close beneath him, and more particularly in front, isthe pedal articulation. It is better, therefore, to excise the cartilagepiecemeal, and to do it carefully, than to attempt, at the risk of injuryto the joint, to make the operation 'showy. '

During removal of the cartilage, the terminal branches of the digitalarteries are wounded, as also are the veins of the coronary plexus. Shouldeither of these stand out with extra prominence from the others, it shouldbe picked up with a pair of forceps, and ligatured with either carbolizedgut or silk. 

Attention should then be given to the flap of skin and coronary cushion. Wherever a sinus has existed in it, it is to be carefully scraped, and alldead portions of tissue removed. This done, the flap is allowed to fallinto position, and is there carefully sutured, not only at the skin of thecoronet, but along the whole circumference of the incision. 

_Dressing of the Wound and After-Treatment_. --The whole secret of thesuccess of this operation is in afterwards maintaining a strict asepsisof the wound. Unless there is reasonable room for belief that this may bedone, the operation had far better not be advised, for if the wound isafterwards suffered to get into a suppurating and dirty condition, the laststage of the case may be worse than the first Synovitis and arthritis, withcertain anchylosis of the joint, and a probable loss of our patient, isalmost bound to follow. 

We cannot, therefore, too strongly insist upon the advice that the whole ofthe preliminary antisepticising of the foot that we have described, and theafter maintaining of asepsis that we are now about to relate, _must_ bemethodically and thoroughly carried out. It is of even _more_ importancethan little details in the operation itself. 

In the first and second methods of operating, directly the actual operationis over, the surface of the wound and both surfaces of the skin-flapsshould first be thoroughly douched with a 1 in 1, 000 solution ofperchloride of mercury. Bayer prefers a 1 in 5 solution of iodoform inether. 

Next, either iodoform or chinosol in the powder should be dusted over thewhole surface, including again both inner and outer faces of the revertedskin-flaps. This done the flaps are allowed to fall into position andsutured there with carbolized silk or gut. 

Another liberal application of an antiseptic dressing follows this. Iodoform, iodoform and boracic acid, or chinosol, is freely dusted overthe wound and for some distance around it. Bayer, however, again prefers adressing of the wound, and especially the moistening of the line of sutureswith the 1 in 5 solution of iodoform in ether. 

Over the wound is then placed a protective layer of gauze, impregnatedeither with boric acid, with a mercuric salt, or with iodoform. 

Finally, numerous small and lightly-rolled balls of dry carbolized toware packed regularly over the whole of the operation wound, and the footbandaged. 

Practical points to be remembered in this after-dressing are: (1) Theballs[A] of tow should be numerous enough to exercise pressure upon thesutured flap when the foot is finally bandaged. (2) The bandage shouldbe run on from the coronet downwards, in order to insure pressure beingexerted in the exact position over the sutured flap. (3) Bandages shouldbe used in abundance, commencing always from the coronet, and carefullyapplied so as to exert an even and uniform pressure. (4) The bandagesshould be of clean, unused linen. 

[Footnote A: Bayer recommends that the tow be rolled into cylindricaltampons, each long enough to cross the wound. These are placed on the woundin alternate horizontal and vertical layers, so that when rolled round by abandage they are pressed into an even and compact pad. ]

Once the bandages are adjusted, the hobbles may be removed, and thetourniquet loosened. Directly the tourniquet is removed there is a steadyoozing of blood through the bandages, no matter how many we have put on. This should occasion no alarm, as experience has taught that the carefulattention to antiseptic measures observed throughout the operation has theeffect of maintaining the lowermost dressings, those next to the wound, ina state of asepsis. The bandaged foot should now be wrapped in a piece ofthick clean cloth or placed in a boot. 

If our antiseptic precautions have been thorough, the dressings andbandages so adjusted may be allowed to remain without disturbance for fromeight to fourteen days. In this, however, the veterinary surgeon must belargely guided by the symptoms of his patient. If, at the end of thefirst three or four days, the animal maintains a vigorous appetite, if hecommences to place a little weight on the foot, and if the thermometergives no indication of a rise beyond the one or two degrees of ordinarysurgical fever, then the surgeon may know that things are proceedingsatisfactorily. Pawing movements with the foot, inability to place weightupon it, loss of appetite, an increase in the number of respirations, anda serious rise of temperature, denote the opposite state of affairs. Thewound is in all probability suppurating. The bandages and dressings shouldtherefore be removed, and the wound either redressed and bandaged, ortreated as an ordinary open wound. 

Ordinarily, however, if the operation has been properly performed, healingtakes place by first intention, and the wound when the bandages are removedat the end of the first or second week appears clean and _dry_. 

Having assured ourselves that such is the case, we dress the foot inexactly the same manner as before, save that so many bandages are not puton. A similar dressing is repeated weekly until such time as the woundshows sufficient growth of horn--quite a thin pellicle--to act as aprotective. It may then be left undressed, except for some simple hoofdressing and a bandage. 

Complete healing of the wound takes from about four to eight weeks, at theend of which time the animal can be again gradually put into work. Thelabour, however, should be light, and quite three or four months should beallowed to elapse before any attempt is made to put him to heavy work. 

Should the second method of operating have been the one adopted, then thereis one slight difference in the after-dressing that needs attention callingto it. In this case we have more or less of a _hidden_ cavity left to dealwith rather than the broad and _open_ wound left in either of the othermethods. This cavity, left by the extirpation of the cartilage, must bethoroughly dressed with iodoform or chinosol, or with Bayer's iodoformin ether. The packing with carbolized tow and the bandaging may then beproceeded with as before. 

In conclusion, we may say that the operation is one of some delicacy, andneeds a good surgeon for its successful performance. Furthermore, no one ofthe antiseptic precautions we have advised can be omitted. It is, perhaps, these two considerations (and in justice to the English surgeon we shouldsay most probably the latter of them) that have prevented this operationfrom being generally adopted. 

That it is successful there is no gainsaying. Professor Bayer, of theVienna School, with whose name is associated the last of the three methodsof operating we have described, is enthusiastic in praise of the operation, and says: 'The favourable results that I have got by this operation havecaused me wholly to abandon the medicinal treatment, and to prefer in allcases the surgical operation as being the best means to the end. '

_Partial Excision of the Lateral Cartilage_. --Discarding the somewhatelaborate methods we have just described, there are English operators whoremoved the necrosed portion only of the cartilage, and do so in whatappears at first sight a comparatively rough-and-ready manner. 

The apparent roughness is that they do not concern themselves withconserving the coronary cushion, and hesitate but little in cuttingportions of it bodily away. One would imagine that in this case the quarterof the side operated on would be always more or less bare of horn. Such, however, is not the case. 

To perform this operation the animal is again cast and chloroformed. Someoperators, however, use the stocks and dispense with the anæsthetic. Thefoot is first well cleaned with soap and water and a stiff brush, and thehair of the coronet over the seat of operation shaved. Again, too, the hornof the affected quarter is rasped until it yields easily to pressure of thethumb, and the whole of the foot washed in an antiseptic solution. 

A probe is now inserted into the opening at the coronet, and the directionof the fistula noted, after which the foot is firmly secured, and anEsmarch bandage and tourniquet applied to the limb. 

This done, a triangular or wedge-shaped portion of skin, coronary cushion, and thinned horn is removed with a strong sage-knife or scalpel. 

The base of the wedge-shaped portion removed contains the opening of thefistula, and the apex of the wedge should reach to the bottom of the sinus(see Fig. 142). 

After the horn is removed and the fistula followed up, it is sometimesfound that what we at first thought was its end, it may now be continued inan altogether different direction. 

It is again followed up with the probe, and the horn and sensitivestructures excised until we are quite certain we have reached its furthestextent. 

Attention should next be paid to the cartilage. Wherever spots of necrosisare found, as indicated by the pea-green colour of the affected parts, theymust be _carefully_ excised. Care should be taken in so doing to carry theline of excision some little distance around the visibly affected parts. This is done that we may be quite certain nothing at all remains calculatedto give rise to further trouble. 

It goes without saying that, in addition to the necrosed cartilage, allother diseased and necrotic tissues should also be removed. The os pedis isoccasionally found necrotic just where the cartilage joins it, or it may bethat a small portion of the sensitive laminæ, by reason of its _liver-red_or even gray coloration, gives evidence of death of the part. 

The former must be well curetted, and the latter cleaned carefully with ascalpel and forceps. 

[Illustration: FIG. 142. --PARTIAL EXCISION OF THE LATERAL CARTILAGE BYREMOVING A PORTION OF THE CORONARY CUSHION. The dotted lines show theoutline of the wedge-shaped portion of structures to be removed, includingskin, coronary cushion, horn, and sensitive laminæ. _a_, The opening of thefistula. ]

The operation finished, the foot is again douched in an antisepticsolution, the wound mopped dry with carbolized tow, dressed with either ofthe dressings described on page 358, and finally bandaged. The dressingshould be changed every three days only, unless in the meanwhile pawingmovements and other symptoms of distress indicate their removal. 

The length of coronary cushion removed in this operation is from 1/4 to 1/2inch (we ourselves, however, have seen it more), and yet its loss seems tooccasion no serious after-trouble beyond a slight deformity of the partsbeneath. The sensitive structures become sufficiently covered with horn, and the animal in nearly every case is returned to work, while in a greatmany instances he may also trot perfectly sound. 

Simple though the operation may appear, and apparently rough in its method, it is nevertheless successful in effecting a cure in cases where blisters, plugging, injections, and other means have failed. 

Mr. W. Dacre, M. R. C. V. S. , [A] after reading an article on the operationbefore the members of the Lancashire Veterinary Medical Association, says:'My observations have not been based on a single case, and having had nineof them, and all of them successful, I felt it to be my duty to bring thissubject before the Society. '

[Footnote A: _Veterinary Record_, vol. V. , p. 407. ]

Mr. T. W. Thompson, M. R. C. V. S. , [A] says: 'In a great number of cases I haveremoved a 1/2 inch of the coronary band. .. . I have performed the operationa great number of times, and have never seen a foot that has been damagedby it. '

[Footnote A: _Ibid_. ]

Professor Macqueen[A] says: 'I do not spare the coronary band or sensitivelaminæ when I find those parts diseased. I do not unnecessarily damagethose structures. At the same time, I am confident that excision of a pieceof the coronary band or removal of a few sensitive laminæ has not theuntoward consequences so much dreaded in former days. '

[Footnote A: _Ibid_. , p. 714. ]

Mr. John Davidson, M. E. C. V. S. , [A] says: 'The treatment described, ifcarefully carried out and details attended to, will be found a success indealing with the majority of cases of quittor. If I may be permitted to sayso, without being considered boastful, I have yet to see the first casethat has resisted the treatment. '

[Footnote A: _Ibid_. , vol. Xiv. , p. 769. ]

Should our case of quittor be complicated by caries of the bone, this must, where possible, be scraped or curetted until the whole of the diseasedportion is removed, and a healthy surface is left. After-dressing must thenbe carried out as in other cases. 

The treatment of ossified cartilage will be found under treatment ofside-bones, and the methods of dealing with penetrated articulation andpurulent arthritis are treated of in Chapter XII. 

_Surgical Shoeing in Quittor_. --In the case of simple or cutaneous quittor, no alteration in the shoeing is necessary. 

When the condition becomes sub-horny, however, and particularly when it issituated in the region of the quarters, ease is afforded to the diseasedparts by removing the bearing of the shoe in that position. 

Should there be no dependent opening at the sole, then the best shoe forthe purpose is an ordinary bar shoe (Fig. 68), with the bearing eased underthe affected quarter. 

If, however, there is a dependent orifice, or one is expected, then it willbe necessary either to leave the animal unshod or to provide him witha shoe that admits of dressing the lesion. In the latter case the mostsuitable shoe will be found to be either a three-quarter shoe (Fig. 102)or a three-quarter bar shoe (Fig. 103). Many operators, however, keep theanimal unshod. We must say ourselves that we consider a shoe useful aftereither of the operations for removal of the cartilage, if only to assist inmaintaining the bandages and dressings in position. 

In this case a very useful shoe will be the three-quarter bar shoe. With alittle manipulation the bandages are easily run under the bar portion ofthe shoe, and a few of their turns every now and again wrapped round thebar in order to keep the whole firmly in position. 

In connection with tendinous quittor, when septic matter has gained thesheath of the flexor tendons, there is, for a long time after healing ofthe fistula, a marked tendency for the animal to go on his toe. To a largeextent we judge this to be due to slight adhesions between the two tendonsbrought about by the growth of inflammatory fibrous tissue. In such casesbenefit is sometimes derived from the application of a shoe with anextended toe-piece (see Figs. 84 and 108). 

C. OSSIFICATION OF THE LATERAL CARTILAGES, OR SIDE-BONES. 

_Definition_. --An abnormal condition of the lateral cartilages, in whichthe substance of the cartilage becomes gradually removed and bone formed inits place. 

[Illustration: FIG. 143. --OSSIFIED LATERAL CARTILAGES (SIDE-BONES). ]

_Symptoms and Diagnosis_. --Side-bones are nearly always met with in heavydraught animals, and are rarely seen in the feet of nags. They are, moreover, nearly always confined to the fore-feet. In the ordinary waylittle need be said concerning their characteristics, and the way in whichthey may be detected. Neither need any concern be ordinarily manifestedwith regard to the effect they may have on the animal's gait and futureusefulness. Seeing, however, that side-bone constitutes one of therecognised hereditary diseases, and that at the various agricultural andhorse shows its existence or otherwise in a certain animal is a matter ofgreat importance, some little attention must be given to these two points. 

With a side-bone anywhere approaching full development, diagnosis is easy. The thumb is pressed into the coronet over the seat of the cartilage, when, in place of the elasticity we should normally meet with, we have the solidresistance offered by bone. In some instances diagnosis is even easierstill. We refer to those cases in which the side-bone stands above thelevel of the coronet with such prominence as to be readily _seen_ andrecognised without manipulation, and where its growth has caused distinctenlargement and bulging of the wall of the affected quarter. It seems thatin such cases the bone-forming process does not end with simply depositingbone in place of the removed cartilage, but that, after that isaccomplished, the bone still continues to be produced, as in the case of anexostosis elsewhere. 

Although diagnosis in cases such as these is easy, it becomes a verydifferent matter when we are called upon to give an opinion in cases whereossification of the cartilage is only just commencing. Whether the resultof our examination is to decide the sale or purchase of an animal, todetermine his fitness or otherwise to enter the show-ring, or to merelyadvise a client as to whether or no a side-bone is in course of formation, our position is equally difficult, and in either case our examination mustbe searching. 

Perhaps the best advice we can give is to say that the whole of thecartilage must be manipulated both with the foot _on_ and _off_ the ground. What the reason may be we do not pretend to say, but it is a well-knownfact that in many instances the cartilage, with the foot bearing weight, is so rigid as to at once convey the impression that ossification hascommenced or is even far advanced. And yet that same cartilage, with thefoot removed from the ground, is as pleasantly yielding to pressure of thethumb as the most exacting of us could wish for. In any case, then, wheredoubt exists, the foot should be lifted to the knee, and the cartilagecarefully examined with the foot in that position. If, then, at any spotabove the normal contour of the os pedis we meet with hardness or rigidity, we are to look upon that foot with suspicion. Nevertheless, providing ourconscience is sufficiently elastic, the animal may be passed _sound_ so faras the _existence_ of a side-bone is concerned. We know, however, that withcommencing rigidity we may ere long expect one, and if our opinion is askedwith regard to that particular, it must be admitted that with rigidity ofthe cartilage once commenced it is usually not long afterwards before afully-developed side-bone makes its appearance. 

As is only to be expected, the first noticeable hardening of the cartilageis to be found near the normal bone. We may thus look for it moreparticularly in the lower portions of the cartilage. We think we may say, too, that in the vast majority of cases the ossification of the cartilagecommences in its anterior half. It is thus brought about that often weare called upon to examine and report on the condition when we have_anteriorly_ a side-bone in course of formation, and _posteriorly_ aperfectly normal cartilage. It is to the latter half of the cartilage thatdealers and others mainly, if not wholly, devote their attention. A horsewith the cartilage in this transition state will therefore pass muster, anda nice little point of ethics has again to be decided by the veterinarysurgeon before giving his signature to a certificate of examination of ananimal in this condition. 

With regard to alteration in gait, we may say at once that side-bones inheavy animals are not often the cause of lameness. In fact, where the footis well developed, when neither the foot as a whole nor the phalangealbones give evidence of disease, and where the pasterns are fairly obliqueand well formed, this alteration of the cartilages may be looked upon as ofno serious import at all. Neither is the side-bone due to blows or otherinjuries likely to be productive of lameness--that is, always supposing, ofcourse, that the foot in other respects is of good shape. If lameness ismet with at all, then it is where we have a foot that is in other respectsunsound, with badly contracted heels and upright 'stumpy' hoof, or whereside-bones have occurred in a young animal, and have already reached alarge size before the horse is put to labour. In this latter case, theadded effects of concussion and the evil influences of shoeing aresufficient to turn the scale. Directly the animal, previously sound, isasked to work, lameness is the result. 

It follows, therefore, that side-bone in the feet of young animals is offar more serious import than when occurring in older horses. In a naganimal they constitute a positive unsoundness, and lameness in this case ismore often than not an accompanying symptom. 

_Causes_. --To commence with, we may remark that, although met withsometimes in very early life, side-bones are seldom, if ever, congenital, and that more often than not they may be looked for in animals of threeyears old, or older, seldom earlier. They appear, in fact, only when theanimal is shod and commences work. 

This at once suggests two of the principal factors in theircausation--namely, concussion and loss of normal function. Directly thehorse is put to work he has for a great part of his time to travel uponroadways--either macadamized roads or town sets--where everything iscalculated to bring concussion about. In addition to that he has thelateral cartilage itself thrown largely out of action by shoeing. Weexplained in Chapter III. (p. 66) that the chief function of the cartilagewas to take concussion received by the plantar cushion and direct thegreater part of it outwards and backwards. Now, with the animal shod, theplantar cushion does not itself, as normally it should, receive concussion. By the shoeing the frog is lifted from the ground, and the plantar cushion, together with the cartilage, taken largely out of active work. In otherwords, the normal outward and inward movements of the cartilage areenormously reduced. 

It is fair, we think, to take it that the mere fact of the lateralcartilage persisting _as_ cartilage is due in large measure to its constantmovement. Directly, therefore, it is placed in a state of comparativeidleness, then it commences to ossify, more particularly if there should atthe same time be a tendency to a low type of inflammation of the parts. 

Does this latter exist? We may safely say that it does. It is in this way:The secondary effect of loss of ground-pressure upon the frog and plantarcushion is to bring about contraction of the heels. With this we getcompression of the parts within, with a certain amount of irritation andthe exact low type of inflammatory phenomena calculated to assist in thebone-forming process. 

The fact that concussion acts as a cause explains in great measure how itis that side-bones are more frequent in cart animals than in nags, and alsowhy they should be more common in the fore-feet than in the hind. Taking, in both animals, a rough calculation as to the weight of body carriedby feet of a certain size, we notice at once that the cart animal hasproportionately more weight to carry than has the nag. Concussion to thefoot is therefore greater. The greater part of the body-weight is borne bythe fore-limbs. Concussion is therefore greater to the fore-feet than tothe hind. 

This, however, does not explain altogether the comparative immunity of thenag animal from this defect. He, too, must also be subject to the effectsof concussion, especially when his higher and faster action is taken intoaccount. To our minds there is only one explanation to be offered here. Wepoint at once to the years of constant and judicious breeding of the nag. Compare that with the relatively few minutes that have been devoted to amore careful selection of the cart animal, and we at once see a possibleexplanation. That the explanation holds some amount of truth is borne outby the fact that, since a greater attention has been paid to the selectionof our cart animals, side-bone has grown a great deal less common. 

Is side-bone hereditary? We can best answer that by saying that, someseveral years ago, the Council of the Royal College of Veterinary Surgeons, at the request of the Royal Commission on Horse Breeding, drew up a list ofthose diseases 'which by heredity rendered stallions so affected unfit asbreeding sires, ' and that in that list was included side-bone. 

Side-bones, therefore, are hereditary. We think, however, the statementneeds qualifying. It is in this way: side-bones occur only at a certain, usually well-defined, time after birth, and we might say are _never_congenital. They occur only after the animal has been put to work, and aremore or less plainly due to mechanical causes--namely, the ill effects ofshoeing and concussion. The cause of their appearance, in short, is moreplainly extrinsic than intrinsic, and side-bone in the horse is, asProfessor McCall puts it, about as much due to heredity as is corn on thehuman foot. 

Between these two opinions--that they are plainly hereditary, and that theyjust as plainly are not--it is well to strike a middle course. They are, wewill say, hereditary in this way: So long as a cart animal is bred, to putit vulgarly, 'top-heavy' (that is, with a body out of reasonable proportionto the feet that have it to support), so long will the foot be subjected toa greater concussion, and so long will side-bones in such animals commenceto make their appearance at about middle life. 

In addition to the causes we have now mentioned, side-bones are oftenthe result of other diseases of the foot. They thus occur as a sequel tosub-horny quittor, to suppurating corn, to complicated quarter sand-crack, or to the inflammation of the parts occasioned by a prick. They also arisein many instances from the effect of a prick or injury to the coronet. Among the latter we may mention treads from other animals, and treadsinflicted by the animal himself with the calkin of an opposite shoe, or therepeated injury occasioned by the shafts being carelessly allowed to dropon to the foot. In severe cases of laminitis, too, the cartilages arenearly always affected. In this instance the inflammatory phenomena in theos pedis no doubt give rise to an abnormal activity of bone-forming cells. The cartilage is invaded, and the side-bone formed (see Fig. 118). 

_Treatment_. --In the ordinary way the 'treatment' of side-bone is a thingbut rarely mentioned. The explanation lies, of course, in the fact thatside-bones are so rarely the cause of lameness. When lameness does occurwith a side-bone, and we have reason to believe that the said side-boneis the cause of the lameness, it is well before talking of treatment toquestion ourselves thus: 'In what way does the side-bone cause lameness?'The now generally-accepted answer to that query is the explanation putforward several years ago by Colonel Fred Smith--namely, that the pain, andtherefore the lameness, was due to the compression of the sensitive laminæbetween the ossified and enlarged cartilage and the non-yielding and oftencontracted wall of the quarters. That, in fact, constitutes the basis uponwhich Smith's operation for side-bone (that of grooving the wall of thequarters) is founded. 

Before describing the operation, however, we may say that we are now ableto understand that older operators who claimed success for other methods oftreatment, were to a very great extent justified in so doing. 

For instance, take the combined treatments of firing and blistering, andthe use of a bar shoe. Here the beneficial action of the cautery and theblister may be largely problematical. The bar shoe, however, would bealmost certain to give good results. Frog-pressure with the ground would beagain restored, and the contraction of the heels removed. Pinching of thesensitive structures would be diminished, and the lameness cured. 

Take, again, the treatment of 'unsoling. ' It was barbarous, we knowbarbarous, because unnecessary and easily avoidable. It was practised, however, certainly very little more than two decades ago, and practised bymen of standing in the profession. Without dragging the case to light againby mentioning the names of those concerned, we may mention that notmany years ago a highly respected member of the profession was, at theinstigation of the Royal Society for the Prevention of Cruelty to Animals, prosecuted for practising unsoling for the relief of side-bone. Practicallyonly one other member of the profession was able to come forward and defendthe operation on the score of its utility. We see now, however, that--asdoes Smith's operation--unsoling does permit of the greater expansion ofthe heels. The contraction is done away with, the pressure on the sensitivelaminæ again diminished, and the lameness relieved. 

Not that we are attempting to defend the operation--far from it. We simplymention it as interesting, and quote this and the use of the bar shoe (withboth of which methods older operators have claimed success) merely asevidence that the operation of Smith is based on a logical foundation. 

When treatment is decided on, therefore, we may first advise blistering andthe use of a bar shoe. After that, should the lameness continue, and shouldwe still judge the side-bone to be the cause of it, the operation may beadvised. 

As we have said before, the operation consists in so grooving the wall asto allow of the quarters widening sufficiently to relieve pressure onthe parts within. In one or two previous portions of this work we haveconsidered operations involving this procedure. Before detailing theoperation here, therefore, we will first describe the instrumentsnecessary, and the most satisfactory methods of incising the horn. 

To begin with, it must be remembered that all methods of hoof section havefor their object the after-expansion of the horny box, and that this canonly be brought about by making each groove complete from coronary marginto solar edge of the wall, and carrying it, throughout its length, _deepenough to reach the commencement of the sensitive structures_. 

To this end, therefore, the operator must bear in mind the comparativethickness of the various parts of the wall, and must, in particular, remember the relative thinness of that portion of horn forming the outerboundary of the cutigeral groove, and accommodating the coronary cushion. 

For the making of the incisions there is the special saw devised for thisoperation by Colonel F. Smith, A. V. D. , and which we illustrate in Fig. 144. With this the wall is sawn through _until the depth arrived at is equal towhat is indicated by a previous examination of the thickness of the crustas viewed from the solar surface_. Here Colonel Smith says: 'I stronglyadvise everyone to use a metal gauge (a thin piece of material) tointroduce into the incision made by the saw, and run it up and down toascertain whether the wall is properly divided throughout. The depth towhich this should be done we know from the previous measurements of ourgauge on the crust. '

[Illustration: FIG. 144. --SMITH'S SIDE-BONE SAW (EARLY PATTERN). ]

Should the saw be of a pattern in which the set of its teeth makes only anarrow incision, [A] it should, while operating, be kept well oiled, andshould be withdrawn every few seconds in order that the horn-dust lying inits teeth may be examined. If this is getting slightly blood-stained, we know, of course, that the sensitive structures are reached, and theincision has been carried far enough. In so judging the depth of theincision, however, care must be taken to see that the top of the coronarycushion is not injured with the saw, for if this is done the bloodtrickling into the depth of the incision will tinge the horn-dust, and givethe false impression that the incision is sufficiently deep. 

[Footnote A: That is Smith's older pattern. The newer pattern (Fig. 145)has the teeth so set as to make an incision wide enough to be looked into. In this case the depth arrived at is to be judged by the appearance of thebottom of the incision. ]

If the operator has had no previous experience of the use of the saw inthis operation, he must also be careful to avoid placing too great apressure on the teeth of its lower third. This is done by keeping the handtoo greatly depressed. Again, this leads to wounding of the sensitivestructures (this time at the lower end of the incision), and again theoperator is confused by the blood thus allowed to run into the groove. 

The only portion of horn difficult to operate on is that immediately underthe coronet. This is best severed with a succession of downward movements, and is easier performed with Smith's later pattern of side-bone saw (Fig. 145) in which the set of the foremost teeth is reversed. 

[Illustration: FIG. 145. --SMITH'S SIDE-BONE SAW (IMPROVED PATTERN). ]

In making these grooves we must say that we think the use of the specialsaw may be dispensed with, and the incisions just as easily, or, at anyrate, just as successfully, made with the knife. Those who select to usethis instrument should choose a narrow-topped and sharp searcher, or amodern shaped drawing-knife of suitable size, such as those depicted inFig. 46, _a_ and _b_, and they will find their work much easier ifthey will make the first steps in the incisions with an ordinary flatfiring-iron. By the use of the latter instrument the grooves are madeconveniently open along their tops, and room left for nicely finishing themore delicate manner of removing with the knife the softer horn near thesensitive structures. 

Those whose leaning is towards the use of special instruments, but who, atthe same time, do not care to use the saw, will find their wants suppliedin the hoof plane (Smith's), Fig. 146, or the hoof chisel (Hodder's), Fig. 147. With the hoof plane the groove in the wall is made by a succession ofdownward scraping movements, while with the chisel the cut in the wall ismade either from below upwards, or from above downwards, according asthe foot is held forward or backward--whichever, in fact, comes mostconvenient. 

[Illustration: FIG. 146. --HOOF PLANE (SMITH'S). ]

When using the knife or the hoof plane it is not often that the sensitivestructures are injured. In all cases, however, no matter what theinstrument used, the metal gauge should be employed when the sensitivestructures have been touched, and the operation obscured by blood. 

[Illustration: FIG. 147. --HOOF CHISEL (HODDER'S). ]

Our instruments at hand, the operation may be proceeded with. The firststep is to ascertain the extent of the side-bone, and to determine theposition of the incisions. To do this the coronet is felt with the thumb, and the anterior extremity of the side-bone noted. This is marked on thehorn with a piece of chalk, and a vertical line dropped from this positionto the inferior margin of the wall (Fig. 148, 1). The line crosses the hornfibres obliquely, and is purposely made in that direction in order that itsinferior end may be far enough back to avoid the last nail-hole. Should theside-bone reach very far forwards, it may be wise to cause this line toslant from before backwards (see dotted line _a_, Fig. 148). Unless this isdone, it is found that in some feet so much of the wall is isolated at thebottom that insufficient is left to nail the shoe to. 

The next line to be made is the rear one. Its correct position isascertained by first noting the junction off the wall with the bar (seegroove 2, Fig. 149); and its inferior end must be just anterior to theinflexion of the wall. This is done that we may avoid cutting the bar. Theposition of the lower end of the rear line thus ascertained, it is runupwards with the chalk in the direction of the horn fibres. 

[Illustration: FIG. 148. --DIAGRAM ILLUSTRATING THE POSITION OF THE GROOVESIN THE WALL IN COLONEL SMITH'S OPERATION FOR SIDE-BONE. 1, 2, and 3, markthe grooves in the order in which they are made; the dotted line _a_ marksthe position taken by the anterior line when the side-bone, is one reachingfar forward, while the dotted lines _b_ and _c_ mark the position of theadditional grooves to be made if thought necessary. ]

The third line is made in such a position as to divide into two equalportions the wall between lines 1 and 2. Here, however, some operatorsprefer to make two, or even three, lines, adding those as at _b_ and_c_, Fig. 148; and Smith himself says that a multiplicity of lines is anadvantage rather than not. 

In any case, having once determined the position of the lines, they shouldbe plainly marked out with chalk, and then viewed from a distance withthe foot on the ground, in order to judge of their regularity. If we aresatisfied with them, we then lightly mark them with the saw, with the hotiron, or with the knife, whichever instrument we may be intending to use. 

Unless the details are methodically carried out as here described, it isprobable that more of the foot will be isolated than is necessary, and thatas a consequence very little is left to which to nail the shoe. 

[Illustration: FIG. 149. --DIAGRAM ILLUSTRATING THE POSITION OF THE GROOVESMADE IN THE HOOF IN COLONEL SMITH'S OPERATION FOR SIDE-BONES. 1, 2, and 3, show the grooves in the wall in the order in which they are made; 4 showsthe groove made at the junction of the sole with the wall. ]

The incisions are then made with the saw or the knife, with the footheld in a convenient position by an assistant. That usually found mostcomfortable for the first incision is with the foot held forwards andplaced on an assistant's thigh in the position adopted for 'clenching up'when shoeing, while that for the rear incision is with the animal's kneeflexed, and the foot held well up to the elbow. In this, however, eachoperator will suit himself. 

Should the preliminary steps in making the incisions be performed with theiron, it will be easiest done with the foot on the ground. 

When the incisions through the wall are complete, our attention must begiven to the sole. A drawing-knife is here used, and a further incisionmade over the white line so as to destroy the union of the sole with thewall between incisions 1 and 2, and so completely isolate the portions ofwall included within the four grooves (see groove 4, Fig. 149). When thisis done it should be found that the portions of the isolated wall springreadily to pressure of the thumb. 

The inferior or wearing margin of the isolated wall must now be so trimmedthat it takes no bearing on the ground when the opposite limb is held up byan assistant and full weight placed upon the foot. 

For a day or two after the operation lameness is intense. This is to betreated with hot poultices or hot baths, and and soon disappears. Three tofour days later a bar shoe is nailed on (taking care that the bearing ofthe quarters is still eased), and the hot poultices still continued. Fourdays later still walking exercise may be commenced, to be followedshortly afterwards by trotting. At about the twelfth day some animals mayconveniently be put to work, while in other cases a fortnight, or even amonth, must elapse before this can be done. When put to work early, it iswise to fill in the fissures made in the wall with hard soap, with wax, orwith a suitable hoof dressing, in order that irritation of the sensitivestructures with outside matter may be prevented. 

This operation is soon followed by remarkable changes in the shape of thefoot. At about the third week the coronet shows signs of bulging, and theupper part of the wall operated on is often so protruding as to render thefoot wider here than at the ground surface. This is a sign that the case isdoing well. 

Should no improvement be noticed at the end of three weeks or a month, orshould the grooves become filled from the bottom (which they do remarkablyfast), then the incisions must be deepened, the exercise reduced, and thefomentations or poulticing repeated. So treated, many cases of side-bonelameness will be relieved, if not entirely cured, and, should the worsthappen, and no alteration in the lameness is noticeable, no harm will havebeen done to the foot. In this connection, the originator of the treatmentsays: 'I may assure those induced to doubt either their diagnosis or thevalue of hoof section that no harm is done to the foot, even should theoperation be of no value. It may do much good; it cannot do harm. Theoperation will never succeed until the inherent timidity of sawing orcutting into the wall is overcome. The _incisions must be deep, and of thesame depth from the coronet to the ground_. '[A]

[Footnote A: _Journal of Comparative Pathology and Therapeutics_, vol. Iii. , p. 313. ]

It is well to remark here that the operation of hoof section cannot beexpected to succeed in every case. The last man in the world to claim thatfor it would be its originator. Failure to relieve the lameness may beaccounted for in a variety of ways. First, of course, will come errors indiagnosis. No one of us is infallible, and the lameness we have judged asresulting from side-bone may arise from another cause. There are, too, complications to be reckoned with, the existence or absence of which cannotalways be definitely ascertained. Such are: Ringbone, especially that formof ringbone known as 'low'; bony deposits on the pedal bone, either on itslaminal or plantar surface, or even changes in the navicular bursa. 

CHAPTER XI

DISEASES OF THE BONES

A. PERIOSTITIS AND OSTITIS. 

We head this section, Periostitis _and_ Ostitis, for the reason that inactual practice it is rare for one of these affections to occur without theother. The periosteum and the bone are so intimately connected that it isdifficult to conceive of disease of the one failing to communicate itselfin some degree to the other. Pathologically, however, and for purposes ofdescription, it is more convenient to describe separately the abnormalchanges occurring in these two tissues. 

With the main phenomena of inflammation occurring elsewhere we presumeour readers are aware. Briefly we may put it, that under the action of anirritant, either actual injury, chemical action, or septic infection, the healthy tissues around react in order to effect repair of the partsdestroyed. Also that this reaction involves the distribution of a greaterblood-supply to the part, with an abundant migration of leucocytes, andthe outpouring of an inflammatory exudate, together with symptoms of heat, pain, redness, and swelling of the affected area. And that in chronicinflammations, owing to persistence of the cause, the process of repairthus instituted does not stop at mere restoration of lost tissue, butcontinues to the extent of forming an abnormal quantity of such tissue asnormally exists in the parts implicated. 

The process of inflammation in bone is essentially the same. It takes placealong the course of the bloodvessels, and is only modified in its attendantphenomena by the structure of the parts involved. Swelling, for instance, cannot take place in the centre of compact bone tissue. Otherwise, otherchanges occur exactly as in inflammations of other structures. 

When the causal irritant has been excessively severe and the migration ofleucocytes abundant, actual formation of pus may occur, the bony tissuebeing broken down and mingled with it, and an abscess cavity formed. Inmilder cases, affected and necrotic tissue is removed by a process ofphagocytosis, and new tissue (this time osseous) formed in its place. 

In the periosteum we may take it roughly that inflammation runs a coursesimilar to that occurring in soft tissues elsewhere. There is but oneexception, and that, as we shall mention shortly, is connected with itsdeeper layer. 

As we know, the periosteum consists of two layers, an outer fibrous andan inner yellow elastic, and is extremely vascular. Numerous bloodvesselsramify in it, and, with their attendant nerves, break up to enter thenumberless canals of the Haversian system. This extreme vascularity, ofcourse, favours abundant exudation. The exudate, however, is, as it were, shut in by the dense fibrous layer of the membrane, and the result is thatin periostitis it collects between the membrane and the bone, causingswelling and raising of the membrane, and giving rise to excruciating painfrom pressure upon the nerves. 

Should the periostitis be complicated by the formation of pus, then thevessels entering and supplying the bone are, in the suppurative area, destroyed. With their destruction it may happen that we get also death ofa portion of the osseous tissue. This, however, when the suppuration isabundant, cannot commonly occur, as the bloodvessels within the bone--thoseof the medulla--commence to supply blood to the affected part. In cases oftrouble with the bones of the foot, these last few remarks have a specialsignificance. Here we have three bones whose medullary cavity is extremelysmall--almost nil, in fact--which explains in some measure how easy it iswhen suppuration exists to get necrosis and exfoliation of, say, portionsof the os pedis. Necrosis and sloughing of the periosteum itself may alsohappen, but as the extreme vascularity of the membrane is a fairly strongsafeguard against that it is of only rare occurrence. 

In connection with the deep layer of the periosteum, and forming part ofit, are found numerous bone-forming cells (_osteoblasts_). These, underordinary conditions, are relatively quiescent. Under the slightestirritation or stimulation, however, their bone-forming functions arestirred into abnormal activity, thus explaining how easy it is (especiallywith bones so open to receive slight injuries as are those of the foot) toget ossific deposits, the starting-point of which we are quite unable toaccount for. 

With this brief introduction we will now describe such pathological changesas occur in the separate structures, and which we are likely to encounterin the various diseases of the foot. While so doing, we shall drawattention to such diseases as we have previously described in which thepathological conditions we are considering may be met with. 

1. PERIOSTITIS. 

This we shall consider under _(a)_ Simple Acute Periostitis, _(b)_Suppurative Periostitis, _(c)_ Osteoplastic Periostitis. 

_(a) Simple Acute Periostitis_. --This is the periostitis that follows onthe infliction of a slight injury to the membrane--an injury without anactual wound and free from infective material. It is one, therefore, whichwe always judge as existing in those cases where we have distinct evidenceor history of injury, but in which the injury has not been severe enough tolead to fracture or to the infliction of an actual wound. 

Such cases may be those of lamenesses persisting after violent blows uponthe foot--cases where the animal has been kicking against the stablefittings, or where the foot has been partially passed over by the wheel ofa waggon. It may be, too, that in a case of 'nail-bound' a great deal ofthe pain and lameness is due to a simple periostitis caused by pressure ofthe bulged inner-layer of horn upon the sensitive structures. 

Simple acute periostitis may also occur in cases where an actual wound isin existence, but where such wound, fortunately, remains aseptic. We maythus have this condition accompanying ordinary cases of pricked foot, oftreads in the anterior region of the coronet, and of accidental injuries ofother kinds. 

In simple acute periostitis the membrane is thicker and redder than normal, and is easily stripped from the bone. As it is pulled off it is noticedthat there are numerous fibril-like processes hanging to its inner surface, and which draw out from the substance of the bone. These are simply thevessels (bloodvessels and nerves) which, loosened by the inflammatoryexudate, are readily detached and drawn from the Haversian canals intowhich they normally run. In addition to its increased redness, the membranehas a swollen and gelatinous appearance owing to its infiltration with theinflammatory discharges. Simple acute periostitis may and often does endin resolution. On the other hand, it may end in suppuration or may becomechronic. If the latter, then the osteoblasts of the innermost layer becomeactive, and abnormal deposits of bone are the result. 

_(b) Suppurative Periostitis_. --This condition simply indicates thatthe inflammation is complicated by the presence of pus organisms. It is, therefore, a common termination of the simple acute form attending theinfliction of a wound. The wound becomes contaminated, and the case ofsimple periostitis is soon changed into the suppurative form. Once havinggained entrance to the wound, the pus increases in quantity, and slowlyruns between the membrane and the bone. This, however, it does not do toany large extent, showing rather a tendency to penetrate the outer fibrouslayer and gain the outside of the membrane. 

Suppurative periostitis is met with in foot cases, commonly in connectionwith punctured foot. It occurs, too, as a complication in suppurating corn, in severe tread, in complicated sand-crack, as a result of the spread ofsuppurative matter in acute coronitis, and in sub-horny quittor. 

In ordinary cases of suppurative periostitis the pus formed is yellowin colour, creamy thick, and free from pronounced odour--the so-called'laudable' pus of the older writers. It so happens in many cases of foottrouble, however, that putrefactive organisms gain entrance side by sidewith those of pus. In this case the characters of the discharge arevery different. It is distinctly more fluid, is of a pink or even lightchocolate colour, and extremely offensive. In these instances the pusshows a marked tendency to spread, strips the periosteum from the bone, perforates the outer layer of the membrane, and finally infiltrates thesurrounding tissues. 

This forms a near approach to what is known in human surgery as an_infective_ periostitis, and in our subjects is nearly always met with incases of severe prick. Its rapidly spreading character makes it alwaysa dangerous condition, and a punctured foot exuding a discharge of thisnature should always be regarded as serious. The close contiguity ofthe joint (it can never be _far_ distant in foot cases), the spreadingcharacter of the disease, and the rapidity with which the horse succumbs toarthritis, are all factors to be taken into consideration, and to lead to awarning-note being struck when attending a case of such kind. 

A further instance of infective periostitis is that met with in acutelaminitis. The discharge obtained from the sole in these cases very oftenbears the character we have just described, and when one considers thethinness of the keratogenous membrane, one is bound to admit that changesso grave occurring in it cannot fail to spread and infect the periosteum. 

_(c) Osteoplastic Periostitis_. --This is more particularly a chronicprocess, and is, as the suffix '_plastic_' indicates, associated withbone-forming changes in the membrane. It may occur as a consequence ofslight but continued irritation, often without ascertainable origin (seeCase 2, p. 392), or it may be the sequel of acute disease. 

In this form of periostitis the membrane is again swollen and more vascularthan in health, and is also easily separable from the bone. The exposedbone is generally rough, in some cases even spicular, and the inner layerof the removed membrane is rough and gritty to the touch--charactersimparted to it by numerous minute fragments of bone that have been tornaway with it from the more compact osseous tissue beneath. 

The results of an osteoplastic periostitis are frequently met with in thebones of the foot, and are described by veterinary writers undersuch headings as 'Pedal Exostoses, ' 'Ossifying Ostitis, ' and 'PedalOssification' (see Figs. 152, 153, 154, and 155). In many of these casesthe disease is purely chronic, and the original cause nearly alwayswanting. When the foot has been subjected to laminitis of some weeks'duration, the same condition is also met with, being at the same timeassociated with rarefactive osteoplastic ostitis, conditions which weshall shortly describe. Cases we have examined have undoubtedly shown thiscondition of osteoplastic periostitis, the rarefactive and osteoplasticchanges in the bone itself, met with in older cases, occurring no doubtas a result of non-expansion of the horny box. So far as we are able toascertain, there is every reason to believe that in chronic laminitis theaccompanying periostitis leads to the formation of bone, and would, if itwere possible, lead to increase in the size of the os pedis. If proof werewanted of this, it is only necessary to point out the increased growth atpoints where resistance is nil--namely, along the upper margin of the bone(see Fig. 118). However, increase in size elsewhere is prevented by theresistance of the hoof, so that, as the bone-forming process progresses, asit inevitably _must_ under the inflammatory changes going on, it is, as itwere, compensated for by rarefaction or bone-absorption changes occurringsimultaneously with it. 

2. OSTITIS. 

We shall next deal with the inflammatory changes occurring in the bonesthemselves, and shall consider them under (_a_): Rarefying or RarefactiveOstitis, (_b_): Osteoplastic Ostitis, and (_c_): Caries and Necrosis. 

Inflammatory changes occurring in the medulla we may pass withoutconsideration, for in the bones of the foot the medullary cavity is sosmall, and the changes taking place in it of such minor importance, that wemay do this without in any way seriously prejudicing our work. 

_(a) Rarefying or Rarefactive Ostitis_. --By this term is indicated aninflammation of the bone attended by its absorption, the absorption beingdue to the action of certain cells, termed _osteoclasts_. This conditionmay be due to the pressure of tumours, may occur as the result of injurywhen a piece of bone is stripped of periosteum, or may be the result of aninflammation occurring in the periosteum elsewhere. 

A piece of bone undergoing rarefactive ostitis is redder than normal, andthe openings of the Haversian canals are distinctly increased in size. As aresult a greater number of them become visible. Their increase in size isdue to the inflammatory absorption of the bony tissue forming them, and inthe larger of them may be seen inflammatory granulation tissue surroundingthe bloodvessels. This enlargement of the Haversian canals is well seenwhen the bone is macerated, the whole then giving the appearance of a pieceof very rough pumice-stone. 

This process of rarefaction or absorption of bone tissue may be confinedto quite a small portion, or it may be spread over the whole of the bone, rendering it more porous than is normal, but stopping short of completedestruction of the bone tissue (a condition which is sometimes knownas inflammatory osteoporosis (see Fig. 118)). In this latter case thecondition is a chronic one, and the bone tissue remaining often appears tobe strengthened by a compensatory process of condensation. For an exampleof rarefactive ostitis as met with in cases of disease of the feet, we refer the reader to laminitis (see Fig. 118). The osteoplastic orcondensing process that appears to exist simultaneously with it explains, no doubt, how it is that bones so affected do not more commonly fracture. 

A further example of this process is illustrated in Fig. 133. The pressureof a tumour (in this case a keraphyllocele) has led to rarefactive changesin the bone, forming a neat indentation in the normal contour of the bonewhich serves to accommodate the tumour. 

_(b) Osteoplastic Ostitis, Osteosclerosis, or Condensation of Bone_. --This, too, is essentially a chronic process. It may occur as a result of, or, aswe have just shown, exist simultaneously with the condition of, diffuserarefactive ostitis. In this case there is a formation of new bone in theconnective tissue surrounding the vessels in the Haversian canals. As aconsequence the bone affected is greatly increased in density, and manyof the Haversian canals by this means obliterated. The end result is anincrease in size of the bones in such positions as the horny box admits ofit, and a peculiar ivory-like change in their consistence. 

For an example of this, we again refer the reader to the changes occurringin chronic laminitis. 

_(c) Caries and Necrosis_. --_Caries_ is a word which appears to be usedwith a considerable amount of looseness. In addition to the meaning impliedby necrosis (namely, 'death' of the part), caries is generally used toindicate that there is also a condition of rottenness, decay, and stench. It is particularly applied, in fact, when the death of the bone is slowlyprogressive, and is due to the inroads made upon it by putrefactive orseptic matter. 

_Necrosis_ of bone may be the result of any injury, such as severe blows, or pricks and stabs. In such cases it would appear that it is loss of aportion of periosteum that is the starting-point. With death of a portionof this membrane the vascular supply to a portion of the bone is cut off, and necrosis ensues. It may also result from the extension of inflammatoryaffections of the structures adjoining it, as, for instance, the spread ofthe infective material in severe tread, or the encroaches made by pus incases of quittor, suppurating corn, or complicated sand-crack. 

When the necrosed portion of bone is small, and is free from infectiveproperties, it is quite possible that it may, as is the case with smallspots of necrosis in softer tissues, be removed by a process of absorption. It must be remembered, however, that where the necrosis has occurred as aresult of septic invasion this cannot be looked for, for in every case suchreparative changes are worked solely by healthy tissue. If the tissuesaround the necrosis are engaged in dealing with organismal invasion andthe poisonous products thus poured into their working area, their state ofhealth is so weakened that they are unable to successfully combat with thetwo conditions simultaneously. As a consequence, the necrotic piece of bonepersists, and acts as a permanent source of irritation. 

It must be remembered, too, that if the dead portion of bone--even thoughit be free from septic matter--is very large, that it may itself act as acontinual irritant, in which case it again persists, and cannot by naturalmeans be removed. 

In our cases necrosis of bone may be met with in punctured foot, in severecases of tread, in cases of complicated crack, and in suppurating corn. It is met with, too, in navicular disease, in the extension of irritatingdischarges in cases of quittor, and in cases of chronic laminitis where thesolar margin of the os pedis has penetrated the sole. In this latter casethe protruding portion of bone is quickly denuded of its periosteum. Itsblood-supply is destroyed, and necrosis follows. 

_Treatment_. --In simple cases of periostitis, those caused by a blow butfree from an actual wound, the most beneficial treatment is the continuedapplication of cold by means of a hose-pipe or by swabs. If by these meanswe are successful in holding the inflammatory phenomena in check, any largeformation of new bone is prevented, and the case does well. 

When the case is complicated by a wound, then antiseptic measures, such asthose described in the treatment of punctured foot, will at the same timehave to be practised. 

It must be admitted, however, that in all but the most simple casesordinary treatment such as this is of very little use; for with only aslight exostosis in almost any position in the foot, excessive lamenesspresents itself and remains. In such cases nothing is left to us but theoperation of neurectomy. 

When the periostitis and ostitis is the result of a wound, and iscomplicated by caries or necrosis of the bone, the diseased portion ofbone must in every case be laid bare and removed. It so happens that themajority of cases of this kind occur in positions where the diseased boneis easily got at. The lower margin of the os pedis or portions of the wingsare commonly the seat of such changes. We meet with the former in casesof pricked foot, and with the latter in severe cases of tread, or as acomplication in suppurating corn or in quittor. In such cases the animalmust be cast and the foot secured. The wound is then followed up, the hornif necessary removed, and the bone curetted with a Volkmann's spoon; or, ifshowing itself as a sequestrum, removed with a scalpel and a strong pairof forceps. Care must be taken that every particle of the diseased boneis removed, and that no part of it is left to act as an after-source ofirritation. With removal of the diseased portion and a strict attention toantisepsis healing soon takes place. 

_Reported Cases of Periostitis and Ostitis_. --1. 'Figs. 150 and 151represent the phalangeal bones of the off fore-leg of a thoroughbred horsenamed Osman, who was well known as a hunt steeplechaser of considerablemerit in the Midland counties some twenty years ago. I may say that thishorse was under my observation pretty regularly during the whole of hiscareer, and up to the time of his death, from ruptured aorta, when eightyears old. My attention was called to him as a yearling by his owner, whotold me that he sometimes fancied the colt was lame. I went over to seehim, and found that he was unmistakably lame on the off fore-leg. Carefulexamination showed no heat or enlargement anywhere. I advised rest and thecolt became pretty sound, though not quite so--in fact, he never did becomequite sound, and sometimes he was very lame indeed. 

[Illustration: FIG. 150. --EFFECTS OF PERIOSTITIS ON THE PEDAL AND NAVICULARBONES. ]

'Every imaginable sort of treatment was tried short of neurectomy, withoutavail. The curious part of the case was that there never was much heat orany apparent change of structure, nor was "pointing" a very noticeablefeature. The foot always remained a good-looking one. As the horse won agood number of races he was of some value, and was seen by a good manymembers of the profession, who were by no means unanimous as to the causeof lameness. The favourite theory was that it was a sequence of "splitpastern. " A post-mortem examination showed that there was no fracture. There was no adherence of the tendon to the navicular bone nor anyulceration. The morbid changes consisted entirely of osseous deposit asshown in the photographs. The under surface of the navicular bone was muchenlarged and roughened by this bony deposit, which extended on to the ospedis, causing complete anchylosis at each extremity of the navicular. Thelateral cartilages were healthy. The interesting points in connection withthe case are the insidious commencement of osseous disease, its extensivedevelopment, and the entire absence of any external manifestation, throughits being confined entirely within the limits of the hoof. 

[Illustration: FIG. 151. --EFFECTS OF PERIOSTITIS ON THE PEDAL AND NAVICULARBONES. ]

'It should also be noted that the animal was able to undergo a severecourse of training for some years, and to gallop successfully over some ofthe most trying courses in England. During the whole of this time he walkedand galloped apparently sound, but trotted always lame, and generally deadlame. '[A]

[Footnote A: W. E Litt, M. R. C. V. S. , _Veterinary Record_, vol. Viii. , p. 527. ]

[Illustration: FIG. 152. --EFFECTS OF PERIOSTITIS ON THE OS PEDIS. ]

2. 'I herewith send you photographs of three cases of the above disease, occurring in the internal surfaces of the wings of the os pedis. The photoswere kindly done for me by Dr. A. Lingard, Imperial Bacteriologist toGovernment of India. It is a cause of many cases of obscure foot lamenessin India, and frequently accounts for the numerous entries on veterinarymedical history sheets under the heading "Contused Foot. "

'The course of the disease is as follows: The disease makes its appearancevery soon after arrival in India, the animal being admitted to hospitalsuffering with undoubted foot lameness, generally slight. One is soon ledto suspect this disease by negative symptoms of other disease being inexistence. No coronary enlargement or flinching on pressure to the coronet, no shrinkage or wiring in of the heels, neither is the characteristicpointing of navicular present. In the early stages one has false hopesof recovery by finding gradual improvement for a time by fomentation andpoultices, followed by irrigation and stimulants to the coronet, andperhaps the animal is discharged from hospital, to be returned after afew days worse than ever. The disease then becomes insidious and morepronounced, the nodding of the head, even at a walk, more exaggerated, and, in fact, the animal seems afraid to put his foot to the ground, and muchresembles a horse with an abscess in his foot, either from prick or pickedup nail. He absolutely nurses his foot. There is a certain amount of heatalways present. The disease being now well developed, pressure is caused bythe ends of the navicular bone, and they become involved at their pointsby bony deposits. The causes of this disease I attribute, firstly, tohereditary predisposition; and, secondly the exciting cause, standingconfined on board ship, where no doubt pedal congestion takes place. Andperhaps some subjects start it in their marches in mobs down countryin Australia. Concussion may be the cause among older horses, but thespecimens photographed were taken from remounts, that had either done nowork or only very gentle work, in a deeply littered riding school. 

[Illustration: FIG. 153. --EFFECTS OF PERIOSTITIS ON THE OS PEDIS. ]

'_Treatment_. --It is obvious from the position of this disease thattreatment will be of no avail in producing a cure. As already stated, thedisease is insidious and progressive, and it is hopeless to expect toarrest the growths once they are started. Unnerving would no doubt removethe symptom (lameness) of the disease, but an unnerved horse is not of muchgood for army purposes. I therefore consider that once the disease becomesfirmly established it is an unfortunate and incurable one. 

[Illustration: FIG. 154, 155--EFFECTS OF PERIOSTITIS ON THE OS PEDIS. ]

'Post-mortem reveals the small nodular growths on the inner surfaces of thewings of the pedal bone, and if long established the ends of the navicularbone are also involved. Exudation and gradual growth of false materialaround the nodules takes place, which also serves to increase pressure. '[A]

[Footnote A: Captain L. M. Smith, A. V. D. , _Veterinary Record_, vol. Xi. , p. 229. ]

3. 'This case was brought for my opinion. The horse was lame, and walkedsimilar to one that had had laminitis, putting the heel down first uponthe ground. I ordered the patient to be destroyed. You will note theossification of the flexor pedis at its attachment to the pedal bone. I enclose photos of the ground, also of the articular, surfaces of thebone. '[A]

[Footnote A: F. B. Jones, M. R. C. V. S. , _Veterinary Record_, vol. Xi. , p. 230. ]

B. PYRAMIDAL DISEASE, BUTTRESS FOOT, OR LOW RINGBONE. 

_Definition_. --A condition of periostitis and ostitis in the region ofthe pyramidal process of the os pedis, usually preceded, but sometimesfollowed, by fracture of the process, and characterized by deformity of thehoof and an alteration in the normal angle of the joint. 

_Causes_. --In the majority of cases buttress foot is brought about byfracture of the pyramidal process. Thus, although distinct evidence of suchis nearly always wanting, we may assume that the original cause is violentinjury to the part in question. Properly, therefore, one would say thatthis condition should be described under Fractures of the Os Pedis. Itappears, however, that other cases of the kind arise in which fracture isaltogether absent, or in which it is plainly seen to be subsequent to thediseased processes in the bone. For that reason, and also for the reasonthat the condition has come to be known by the name we have given, we giveit special mention. 

_Symptoms and Diagnosis_. --Even when the condition arises as the resultof fracture, the ordinary manifestations of such a lesion are absent. Byreason of the situation of the parts within the hoof we are unable todetect crepitation, and the resulting lameness is perhaps--in fact, nearlyalways is--neglected until such time as any heat or swelling caused by theinjury has disappeared, in which case we are denied what evidence we mighthave obtained from that. All that is presented is lameness, and lamenessthat is at times excessive. But with the lameness there is nothingdistinctive. The foot is tender on percussion, and the gait suggestive offoot lameness, that is all. We are unable, therefore, to make an exactdiagnosis, and the condition goes for some time undetected. 

Later, however, changes in the form of the hoof and the coronet begin toappear. The skin of the coronet, especially in the region of the toe, becomes more or less thickened and indurated, and the same remark appliesto the subcutaneous tissues. The most marked change, however, is thealteration in the shape of the hoof. The wall protrudes at the toe in amanner that has been termed 'buttress-like, ' and has given to the conditionone of its names. This, of course, entirely alters the contour of the hornybox. From being more or less U-shaped, it approaches nearer the formationof the letter V, the point of the V being at the toe. 

In the later stages the coronary enlargement is plainly seen to be due toan extensive formation of bone. It is, in fact, a reparative callus, andthe reason it reaches so large a size is probably to be accounted for bythe pull of the extensor pedis upon the detached pyramidal process. Asmight be expected, this displacement of the fractured portion, with itseffect of giving greater length to the extensor pedis, leads to a backwarddisplacement of the os coronæ upon the pedal bone. As a result there is amarked depression at the coronet, the depression being heightened in effectby the exostosis in front. Pyramidal disease is, as a rule, met with in thehind-feet, but occurs also in the fore. 

_Pathological Anatomy_. --When occurring without fracture, the firstobservable change is a thinning of the articular cartilage of the pyramidalprocess, through which the bone beneath appears abnormally white. Laterthe thinning of the cartilage progresses until at last it becomes entirelyobliterated. This destruction of the cartilage commences first at thehighest point of the articular surface of the pyramid, and graduallyreaches further backward into the joint. While this is taking place the newbone is being formed on the front of the os pedis, below and around theprocess, until, as we have already seen, an exostosis is formed, largeenough to be noticeable at the coronet. This, of course, partly implicatesthe joint and the points of the insertion of the extensor tendon. 

Finally, fracture may, or may not, take place. When it does, the exostosisis larger, and the general deformity of the hoof greater. 

_Treatment_. --Ordinary treatment, such as point or line firing, repeatedblisters, or hoof section, each of which we have tried, appears to beutterly useless. So far as we have been able to gather from the writings ofother practitioners, however, neurectomy returns the animal for a time tousefulness. If the fore-limb is the seat of trouble, either plantar ormedian neurectomy may be practised; if the hind, then the best results areobtained by section of the posterior tibial. 

_Reported Cases_. --1. This animal, a mare, had been rested for lamenessbehind for two or three weeks, and then sent out to work, going sound. Thiswas repeated several times, and each time the coachman reported, "Goes verylame behind after she has been at work about fifteen to twenty minutes. "She always pulled out sound when I saw her in a halter on the followingday, so I had her ridden, and after about seven or eight minutes she beganto go lame in a hind-limb. Her lameness got rapidly worse as she was beingridden, and within a quarter of mile of her first showing lameness, shedropped and carried the lame foot in a way that suggested a badly fracturedpastern. There was no recognisable disease in the limb to account for thislameness. 

'I divided the posterior tibial nerve, and she went back to work movingsound, and continued to work sound up to her death from one of theregularly fatal bowel lesions twist or rupture. 

'She worked nearly two years after unnerving, and developed the usualthickening at the coronet. '[A]

[Footnote A: W. Willis, M. K. C. V. S. , _Journal of Comparative Pathology andTherapeutics_, vol. Xv. , p. 366. ]

2. 'The subject of this note was a chestnut mare, nine years old, and usedfor omnibus work. 

'_History_. --For about two months the mare was lame on the off fore-leg, and in spite of treatment the condition became steadily worse. The offfore-foot was rather long and narrow, and the fetlock-joint was inclinedto be bowed outwards, but the degree of lameness was out of proportion tothese defects, and the diagnosis was obscure. 

'Median neurectomy was performed on May 10, 1902, and reduced the lamenessto about half of what it was before. On June 5 ulnar neurectomy wasperformed, with the result that the mare became sound, and went to workthree weeks later. She continued to work soundly and well, being inspectedfrom time to time. 

'During February of 1903 the coronet began to enlarge in front and slightlyto the outer side, and gradually a ridge of bone grew down from the coronetto the toe. The case, in fact, became a typical one of so-called "buttressfoot, " which my friend Mr. Willis has described as diagnostic of diseaseof the pyramidal process of the pedal bone. Meanwhile the swelling of thecoronet, which appeared to be mainly composed of fibrous tissue, increasedin size, until the whole of the front and sides became involved, assumingthe appearance shown in Fig. 156. 

'In spite of the coronary enlargement the mare worked well, and remainedfree from lameness till June 8, 1903, on which day the limb became swollenup to the site of the median operation. The appearance of the limb closelysimulated an attack of lymphangitis. The mare was kept under observationtill the 13th of the same month, during which time the swelling increased, as did also the lameness to a slight degree. During progression she broughtthe heel to the ground and "rocked the toe, " as in a case of rupture of theperforans tendon. The mare was killed on June 13. 

[Illustration: FIG. 156. --A CASE OF BUTTRESS FOOT. ]

[Illustration: FIG. 157. --FRACTURE OF THE PYRAMIDAL PROCESS IN BUTTRESSFOOT. ]

'_Post-mortem_. --In trying to pull away the hoof from the sensitivestructures with a pair of farrier's pincers, the tendons and ligaments ofthe corono-pedal articulation gave way, leaving the pedal bone _in situ_. The flexor perforans tendon showed inflammatory softening, and was verynearly ruptured through at the level of the navicular bone. There wasslight evidence of navicular disease. The articular cartilage of thecorono-pedal joint had been almost completely removed, and there wassclerosis of the opposed bony surfaces, which by unequal wear had broughtabout deformity of the os coronæ and os pedis. 

There was very old-standing fracture of the pyramidal process (see Fig. 157), with the formation of a false joint between the process and the pedalbone. There was also a recent fracture of the part of the pedal bone whichcarries the articulation for the navicular bone, and this and the tendonlesions probably accounted for the final symptoms of 'break-down. '

Neurectomy enabled us to get a year's useful work out of what wouldotherwise have been a hopeless cripple. [A]

[Footnote A: A. R. Routledge, M. R. C. V. S. , _Journal of Comparative Pathologyand Therapeutics_, vol. Xvi. , p. 371. ]

C. FRACTURES OF THE BONES. 

More or less by reason of the protection afforded them by the hooffractures of the bones of the foot are rare. When occurring they are moreoften than not the result of direct injury, as, for example, violent blows, the trapping of the foot in railway points, the running over of the footwith a heavily-laden waggon, or violent kicking against a gate or a wall. They occur also as a result of an uneven step upon a loose stone when goingat a fast pace, and as a result of sudden slips and turns, in which lattercase they are met with when animals have been galloping unrestrained ina field, or when an animal, ridden or driven at a fast pace, is suddenlypulled up, or just as suddenly turned. 

At other times fractures in this region take place without ascertainablecause, and cases are on record where animals turned overnight into aloose box in their usual sound condition have been found in the morningexcessively lame, and fracture afterwards diagnosed. 

1. FRACTURES OF THE OS CORONÆ. 

Fractures of the os coronæ result from such causes as we have justenumerated, and are nearly always seen in conjunction with fracturedos suffraginis. When this latter bone is also fractured diagnosis iscomparatively easy, a certain amount of crepitus, even when the suffraginisis only split, being obtainable. When the os corona alone is fracturedthen diagnosis is extremely difficult, the smallness of the bone and thecomparative rigidity of the parts rendering manipulation almost useless, and effectually preventing the obtaining of crepitus. It is, in fact, onlywhen the bone is broken into many pieces that crepitus may be detected, andeven then it is slight. 

_Reported Cases_. --1. 'The subject was a four-year old hunter. While atexercise in the morning of August 10 he bolted, got rid of his rider, andran about in a mad fashion, came into contact with a wheelbarrow in anarrow passage, and finally came into violent contact with a wall, whichhad the effect of throwing him down. The rider stated that the animalsuddenly put down his head and managed to get off the bridle; he thenbolted, and the only chance for the rider was to throw himself off. 

'On examination I found the horse unable to place any weight on the offfore-leg, the pastern was swollen and painful, the hollow of the heel wasalso swollen, and there was marked constitutional disturbance. 

'After a short time he would place the heel on the ground and elevate thetoe to a slight degree. On manipulating the pastern slight crepitationcould be discovered, and there was abnormal mobility in the corono-pedalarticulation. On the near fore-leg there were extensive wounds in theregion of the knee, and great laceration of the tissues. The animal wasdestroyed. 

'On examining the leg I found the subcutaneous tissues infiltrated frombelow the knee to the foot, large masses of gelatinous blood-stainedmaterial being present along the flexor tendons and in the hollow of theheel. The inferior articular surface of the os suffraginis was denudedof cartilage anteriorly; the os coronæ was fractured into eight moderatesized, irregular fragments, and ten minute pieces. The surface of theperforans tendon as it glides over the smooth surface at the back of the oscoronæ was lacerated, and minute portions of the bone were found embeddedtherein. '[A]

[Footnote A: E. Wallis Hoare, F. R. C. V. S. , _Veterinary Record_, vol. Xiv. , p. 133. ]

2. 'Here, again, fracture was the result of the animal bolting with hisrider. Trying to avoid collision with a conveyance coming towards him, theanimal slipped on a wooden pavement, sliding along until his near fore-legcame in contact with the wheel of a standing cab. There was considerableswelling from the knee downwards, great pain, and evidence of fracture inthe region of the pastern. 

'Post-mortem revealed the os suffraginis broken into about thirty pieces, and the os coronæ with a piece broken off the inside of its proximalend. [A]

[Footnote A: A. F. Appleton, M. R. C. V. S. , _Veterinary Journal_, vol. Xiii. , p. 411. ]

3. 'The patient was a brown mare used for heavy van work in London. AboutJanuary 10 she was lame, and as she had a cracked heel, was treated bypoulticing for a day, and then by antiseptic lotions. In a week she wassent to work, but the following day lameness returned, and continued tillabout February 15. No special symptom was detected which indicated theexact position of any cause of lameness. Then the lameness increased inseverity, and some swelling around the coronet began to show itself. 

'In consultation with another veterinary surgeon, two possible causes ofthis intense lameness were discussed: one, that we had septic infection ofthe coronet, and that probably the swelling of this part would soften, andsloughs occur; the other, that a fracture of the os pedis or os coronæexisted. The enlargement of the coronet was hard and firm, not particularlysensitive. It was decided to do nothing for a few days. In a week thepain abated, and the mare would put her foot on the ground, and ceased to"nurse" the limb as she had done. When moved over in the box she put alittle weight on the foot, but limped very decidedly. 

'Another week passed, and the pain and lameness further abated, but theswelling around the coronet continued. Perhaps it was a little less infront, but it had not decreased on the inside. It remained firm, and wasnot painful on pressure. It showed no soft places, and the upper part ofthe leg remained free from oedema. 

[Illustration: FIG. 158. --FRACTURE IN SITU (OS CORONÆ). ]

'The diagnosis was now that a fracture existed, and it was proposed tosend the mare to grass for a few months. The consulting veterinary surgeonsuggested that before doing so a blister might be applied to the coronet. This was done. The mare was found next day again on three legs. She hadapparently been down during the night. In a few days the coronet increasedagain in size, and within a week "broke out" in two places. 

'The opinion now formed was that, with a fracture and this additional causeof inflammation around the joint, it would be most economical for the ownerto have her killed. This was done, and a post-mortem examination was madeby Mr. Hunting and Mr. Willis. 

[Illustration: FIG. 159. --WITH BROKEN PORTION REMOVED. ]

'_Post-mortem_. --The foot, cut off at the fetlock-joint, showed extensiveswelling all round the coronet. There were two wounds on the skin--one onthe front of the coronet, the other on the inner side. From both pus andblood had escaped. They both communicated under the skin with a largeabscess cavity. The abscess did not communicate with the joint. The pasternbone was sound. On separating the pastern from the coronet bone thearticular surfaces were of a healthy colour, but the soft tissuesimmediately surrounding them were inflamed. On the centre of the articularsurface of the coronary bone a thin red ring was noticed, and the portionof cartilage within it seemed raised. With the point of a scalpel thisportion was lifted, and was found to be not only cartilage, but a layer ofbone completely detached from the os coronæ. On removing the bones from thehoof the rest of the bone was quite normal, as was the pedal bone. 

'Fig. 158 shows the articular surface of the coronet with the fracture _insitu_; and Fig. 159 the surface from which the broken portion is removedand laid to the side of the foot. 

'Some interesting questions arise. How was the fracture caused? When did itoccur? Between the broken portion and the main bone there was a layer ofgranulation tissue, so that it is certain the injury existed before theblister was applied, and it may possibly have existed from the commencementof the lameness. '[A]

[Footnote A: R. Crawford, M. R. C. V. S. , _Veterinary Record_, vol. Viii. , p. 478. ]

2. FRACTURES OF THE OS PEDIS. 

These also are a result of the causes we have before given. The os pedisis also liable to fractures from pricks, from treads in the region of thewings, and from the malnutrition and careless use of the foot sometimesfollowing neurectomy. 

It is interesting to note that, with fracture of this bone, lameness isnearly always excessive, but that at times it may be entirely absent. Crepitus is, of course, denied us, and in nearly every instance the caseis only diagnosed when the lameness persists and pus commences to form, orwhen grave changes in the normal shape of the foot compel our attention tothe parts. When it is the continued formation of pus that draws our noticeto something more than ordinarily grave, it is in giving exit to the pusthat the fracture is nearly always discovered. 

_Reported Cases_. --Two interesting cases of fractured os pedis are reportedby Mr. Gladstone Mayall, M. R. C. V. S. , in the _Veterinary Record_, vol. Xiv. , p. 54:

1. 'The horse was brought in markedly lame on the off hind-foot, knucklingat the fetlock, and taking a long stride with the injured limb. There wasa punctured wound at the toe. The horn was pared, and antiseptic poulticesapplied. Notwithstanding the antiseptic treatment pus continued to form. Atthe end of a week sufficient horn was removed to ascertain the cause ofthe constant suppuration. A movable object was found at the bottom of thewound, and a piece of bone as large as a sixpence finally removed. Recoverywas uneventful. '

[Illustration: FIG. 160. --FRACTURED OS PEDIS. ]

2. 'A filly was attended for a discharging fistula at the coronet. Externally it had all the appearances of a quittor. At first no historywas given. The filly went scarcely lame at all, and had never been shod. Treatment with poultices and caustic injections was useless. Finally thefilly was cast and the foot examined. A piece of bone, apparently part ofthe wing of the os pedis, was removed, and the case made a good recovery. Subsequent inquiries elicited the fact that the animal had kicked at andhit a gate-post, and it was judged that then the injury had occurred. '

3. 'The subject was a bay horse, nine years old, used for railway shunting. On August 7 he was found to be intensely lame of the near hind-limb, and, after inquiries, there was no evidence bearing on the cause, as is oftenthe case, and at times this comes to light when least expected. 

'I was called in consultation on September 2, and found him sufferingacute pain, with great swelling around the coronet. The foot was examinedthoroughly, and the diagnosis was fracture of the pedal bone, and immediateslaughter was recommended. However, that was not carried out, and he diedon September 22. 

'The post-mortem inspection revealed a complete fracture of nearly thewhole of the articulating surface and the left wing of the pedal bone (asshown in Fig. 160). '[A]

[Footnote A: J. Freeman, M. R. C. V. S. , _Veterinary Journal_, vol. Xxxi. , p. 324. ]

4. A further interesting case is reported by Mr. William Hurrell. [A] Herethe cause was presumably galloping in the field, for the subject, a cartmare running out at grass with her foal, was suddenly found to be lame. 

[Footnote A: _Ibid_. , vol. V. , p. 408. ]

As the lameness continued to increase in severity, Mr. Hurrell was calledin on August 1, and diagnosed the case as one of foot lameness. On thisdate the foot was pared out, and a large accumulation of pus discovered, Poulticing and antiseptic dressings were continued until August 16, when amovable piece of the os pedis was found at the toe. 

On August 25 this detached portion of the bone was removed, and turned outto be the whole of the anterior margin of the os pedis, measuring 3-1/2inches long, and varying in width from 1/2 inch to 1-1/2 inches. OnSeptember 20 the mare was working without lameness. 

3. FRACTURES OF THE NAVICULAR BONE. 

Hidden within the wings of the os pedis, and protected as it is by itstendinous covering and the yielding substance of the plantar cushion, thenavicular bone is even less liable to fracture than either of the otherbones of the foot. 

The most common cause of fracture of the navicular is that of stabs or deeppricks in the region of the point of the frog (see p. 216). Following that, the next most common cause is violent injury. We thus find the navicularbone fractured, together with one or both of the other bones of the foot, when the foot is run over by a heavy vehicle. One such case is reportedby Mr. J. H. Carter, F. R. C. V. S. , where the horse's foot was run over by atram-engine, in which the os pedis and the navicular were fractured inseveral places. [A] A further case is on record where a sharp blow on thefront of the hoof was the cause. In this case the os pedis and otherstructures were uninjured, but the navicular bone was fractured into threelarge, and about half a dozen small, pieces. [B]

[Footnote A: _Veterinary Journal_, vol. Xxxi. , p. 246. ]

[Footnote B: _Veterinarian_ for 1857, p. 73. ]

Fractures of the navicular may occur, however, in which history of a prickor of a violent injury is absent. See reported case below. 

As with fractures of the os pedis and the os coronæ, so with this exactdiagnosis is difficult--we may say almost impossible. With a history ofviolent injury, however, some little regard may be paid to a continued heatand tenderness of the foot, and a distinct inclination on the part of theanimal to go on the toe. Even when the fracture is the result of a prick, and the bone is plainly felt with the probe, we still cannot be positive asto fracture. 

_Reported Case_. --'The animal was a Hungarian, a troop-horse in the 3rdHussars (G. 15). On November 22, 1881, on the march from Norwich toAldershot, the horse suddenly made a violent stumble, very nearly comingon to his knees. The rider declared that he put his foot on a stone. Theaccident caused great lameness in the near fore-leg, and the horse had tobe led the remainder of that day's march. On the following day he was alsoled; but, after going some sixteen or eighteen miles, he was so lame thathe was left at the nearest billet (in Edmonton). He was here attended byMr. Stanley, M. R. C. V. S. , of Edmonton, who pronounced it a case of naviculardisease. I first saw the animal on December 1, 1881, and quite agreed withMr. Stanley that it was a case of foot lameness, though, from the horse'sformer history, I could not think it a case of ordinary navicular disease. I diagnosed it a case of fracture, without displacement, either of the oscoronæ or the navicular bone, but was more inclined to the former than thelatter. This was after a full hour's examination. I failed to find any heatin, or any flinching by manipulation of, any part of the limb; but, inwalking, the horse was excessively lame, going on the toe, and, indeed, trying if possible to keep the foot entirely off the ground. 

'On December 6 the horse was sent on to Aldershot by rail. He was thenwalking better, though still very lame. My only treatment for a short timewas to apply cold water constantly to the coronet and foot. For two hoursdaily this was done by a hose, the remainder of the time by a cold swab. OnDecember 14 I applied a strong blister over the coronet, reaching up to thefetlock. This was washed off about the end of December. The horse was thennot nearly so lame. I then resumed the cold-water treatment, and he gotgradually better, and was sent to light duty on February 18, 1882. He, however, only attended one field-day, and was taken into the HorseInfirmary again on March 8, very lame. Again, there was an entire absenceof heat or pain on pressure, but the same action, viz. , going on the toe. I forgot to remark that he always pointed the toe of the affected leg whenstanding in the stable, and this symptom continued. I put him under thecold-water treatment for a short time, and about the middle of March againapplied a strong blister over the coronet up to the fetlock. This waswashed off about the end of the month, and was succeeded by the cold wateragain. Towards the end of April there was no improvement at all, and Iapplied for permission to destroy the horse. This was carried out on April27, at the recommendation of Mr. Gudgin, I. V. S. , Aldershot, and a Board ofveterinary surgeons. 

'On making the post-mortem examination I first thought the bone was onlypartly fractured or cracked, but on manipulating it, after its being in hotwater a short time, I saw the fracture was complete. '[A]

[Footnote A: S. W. Wilson, M. R. C. V. S. , A. V. D. , _Veterinary Journal_, vol. Xv. , p. 12. ]

_Treatment of Fractures of the Bones of the Foot_. --It will be seen at oncethat in most cases anything in the way of bandaging is well-nigh useless. When the os coronæ is fractured, however, a little more may be added to thenatural rigidity of the parts by enclosing the region of the pastern andthe foot in a plaster-of-Paris bandage. The main treatment, however, inevery case, will be a continual use of the slings for at least seven toeight weeks, by that means compelling the animal to give to the injuredparts the necessary amount of rest. 

With fracture of the os pedis, when such is caused by pricks andcomplicated by a flow of pus, then attention must be given to removal ofthe displaced piece of bone. The pus track is to be followed up with thesearcher, sufficient horn removed with the knife, and the broken piece ofbone removed with a scalpel and a pair of strong forceps, the operation tobe afterwards followed up by antiseptic dressings to the opening. Untilthis is done the wound refuses to heal. 

Fracture of the navicular bone, if in any way diagnosed with certainty, offers us an almost hopeless case, for it appears to be a commonly reportedfact that attempts at reunion are rare. This, in all probability, is dueto the pressure put upon it every now and again, when the animal's weightpresses the bone between the os coronæ and the os pedis above and theperforans tendon below. Even should reunion take place, the resultingcallus, interfering as it does with the movements of the perforans, leavesus a case of incurable lameness. When the fracture is complicated bythe formation of pus, as in the case of prick, then the case, with theattendant purulent synovitis and arthritis, is even more hopeless still. 

Diagnosis of fracture of either of the bones of the foot is, as we havesaid before, extremely difficult. It so happens, therefore, in those casescaused by violent blows, that anything approaching an accurate opinioncannot be given until some months after the injury. After some time we aremet with unmistakable changes in the form of the foot, and are able toassume that the persisting lameness is due to pressure of a reparativecallus within the hoof. In such cases the only treatment of any use is thatof neurectomy. 

CHAPTER XII

DISEASES OF THE JOINTS[A]

[Footnote A: Properly speaking, we have in the foot of the horse but _one_joint--namely, the corono-pedal articulation. 

Although not a joint in the strict sense of the word, we, nevertheless, intend here to consider the navicular bursa as such. In this apparatus, although we have no articular cartilage proper, and no apposition of boneto bone, we still have a large synovial cavity, and in close proximity toit bone. We may, in fact, and do get in it exactly similar changes to thosetermed 'synovitis' and 'arthritis' elsewhere. Therefore, we include thechanges occurring in it in this chapter, and hence the plural use of theword to which this note refers. ]

A. SYNOVITIS. 

_Definition_. --By the term 'synovitis' is indicated an inflammation of thesynovial membrane. It may be either (_a_) _Simple_ or _Acute_, or it may be(_b_) _Purulent_ or _Suppurative_. 

In the simple form there is little or no tendency for the affection toimplicate the other structures of the joint, whereas in the suppurativeform the joint capsule, the ligaments, and the bones soon come toparticipate in the diseased processes, giving us a condition which we shallafterwards describe as acute arthritis. 

(_a_) SIMPLE SYNOVITIS. 

1. _Acute--(Causes)_. --Simple or acute synovitis is nearly always broughtabout by injury to the joint--by blows or bruises, or by sprains of theligaments. At other times it occurs without ascertainable cause, and isthen put down to the influence of cold, or to poisonous materials (as, forexample, that of rheumatism) circulating in the blood-stream. 

_Pathology_. --Uncomplicated acute synovitis never causes death. Thepathological changes in connection with it have therefore been studied incases purposely induced, and the animal afterwards slaughtered. It is thenfound that, as in inflammation elsewhere, the synovial membrane is showingthe usual inflammatory phenomena--that it is thick and swollen as a resultof the inflammatory hyperæmia and commencing exudation. Later, the synovialfluid becomes increased in quantity, is thin and serous, and after a timeis seen to be mixed with the inflammatory exudation poured into it. We thenfind that it has lost its clear appearance, has become thick and muddy, andhas floating in it flakes of fibrin. 

If the case progresses favourably these materials are soon absorbed andresolution occurs. In rarer cases the thickening and congestion of themembrane increases, and the articular capsule becomes so distended with theincreased synovia and accumulated inflammatory discharges that a kindof chemosis occurs. In other words, there oozes through, without actualrupture of the membrane, a thin, blood-stained, and purulent-lookingdischarge. 

It is an important point to note that in cases of synovitis the fringes ofthe synovial membrane become swollen and blood-injected, forming noticeablered elevations at the margins of the cartilages. It is then that thediseased condition soon spreads and runs into arthritis. 

Further, it is important, especially with regard to the question of thedegree of pain and lameness likely to be caused, to note that oftengranulations are thrown out upon the looser folds of the membrane. Asthese increase in size they come to form fringed and villous membranousprojections inserting themselves between the bones forming thearticulation. In such cases there is no doubt that the intense painsometimes observed in these cases is due to pinching of these prolongationsof the synovial membrane by the opposing bones of the joint. 

_Symptoms and Diagnosis_. --Acute synovitis of a joint leads to heat of theparts, pain, distension of the capsule, and, where the joint may be easilyfelt, fluctuation. In the articulation with which we are dealing, however, these last two symptoms are not easily detected, for the surroundingstructures--namely, the lateral and other ligaments of the joint, theextensor pedis tendon in front, and the perforans behind, together with thedense and comparatively unyielding nature of the skin of the parts--aresuch as to prevent distension and fluctuation becoming marked to a visibleextent. We are able to diagnose the case as one of foot lameness, and, witha history of a severe blow or other injury, are able to assume that thiscondition, perhaps attended with periostitis, is in existence. 

When other symptoms present themselves diagnosis may be more certain. Theanimal becomes slightly fevered, throbbing pains in the joint manifestthemselves by irregular pawing movements on the part of the patient. Theanimal comes out from the stable stiff, even dead-lame, and the limb iscarried with the lower joints semiflexed. The breathing is hurried and thepulse firm and frequent, while in a bad case patchy perspiration breaks outat intervals on various parts of the body. If with this we get a puffy andtender swelling in the hollow of the heel, our diagnosis may be certain atany rate as to the existence of joint trouble, although, from reasons wehave given, we may not be able to mark its exact nature. 

2. _Chronic_. --Simple synovitis may in many instances become chronic. Inthis case we have simply a pouring into the synovial capsule of serousfluid, and with it an increased quantity of synovia--this time with anabsence of the usual inflammatory phenomena. Beyond the swelling of thecapsule there is little to be noticed. The joint becomes perhaps a littleweaker, but pain or tenderness and heat are entirely absent. Such acondition, by reason of the natural rigidity of the parts, is not to beobserved in the foot, although at times it must most certainly occur. Examples of such a condition are to be found in bog-spavin, in hygroma ofthe stifle, and sometimes in the fetlock. From a study of these, we knowthat they may be induced by frequent attacks of acute synovitis, fromrepeated slight injuries or bruises, or from strains to the ligaments ofthe joint; or that they may be chronic from the outset. We know, too, thatin such cases the synovial membrane becomes thickened, and that in placesit may have extended somewhat over the edges of the articular cartilages. It is only fair to suppose that such changes occur also in the pedalarticulation. In that case we may take it for certain that the naturalrigidity of the surrounding structures has the effect of pushing thethickened membrane further between the bones of the joint than occurs in alike condition elsewhere, leading, of course, to a lameness that is markedin degree but occult as to cause. 

In our minds there is no doubt that many of the occult and chronic forms offoot-lameness we meet with in practice are in this way to be accounted for. We may, in fact, explain them by suggesting either a chronic synovitisalone, or a synovitis complicated with periostitis. 

_Treatment of Synovitis_. --If a joint has been injured, as we havesuggested, by slight blows or other causes--in other words, if the injuryis subcutaneous, and no wound is in existence--then there is no treatmentwhich offers better results than does the continued application of cold. 

At the same time, the animal should be slung, or, if non-excitable andinclined to rest, allowed at intervals to lie on a thick and comfortablestraw bed, the cold fomentations during such intervals being discontinued. When the case is a marked one and the animal valuable, benefit will bederived from the application of crushed ice. 

The animal's condition must be watched, and the case helped as far as ispossible by the administration of a mild dose of physic, by saline drinks, and, when necessary, by the giving of small but repeated doses of Fleming'stincture of Aconite in order to relieve the pain. In a chronic case therepeated application of a blister is indicated. 

(b) PURULENT OR SUPPURATIVE SYNOVITIS. 

In this condition we have synovitis complicated by the presence of pus. Unlike the simple form, it shows a marked disposition to spread, andquickly involves the surrounding structures. Very soon the ligaments ofthe joint, the periosteum, the articular cartilages, and the bones areimplicated. This, of course, constitutes a condition of acute purulentarthritis. Under that heading, therefore, the condition will be laterdiscussed. 

B. ARTHRITIS. 

(a) SIMPLE OR SEROUS ARTHRITIS. 

With an attack of simple synovitis it may be always assumed that thechanges commenced in the synovial membrane, communicate themselves moreor less readily to the surrounding tissues, and are not confined to thesynovial membrane alone. We may thus have the inflammatory phenomenaasserting themselves in the surrounding ligaments, in the periosteum, inthe bone, and in the articular cartilages. It depends, in fact, upon theseverity of our case whether we call it synovitis or arthritis. The twoconditions merge so the one into the other that no hard-and-fast rulemay be laid down whereby they may with certainty be differentiated. Suchsymptoms, therefore, as we have given for synovitis may be also read asindicating a condition of simple arthritis. The course of the case will bevery similar, and the treatment to be followed identical with that justgiven. 

(b) ACUTE ARTHRITIS. 

_Causes_. --An attack of acute arthritis may commence with the affection ofthe synovial membrane, and spread from that to the other structures. Inother cases the disease of the synovial membrane, and after it the diseaseof the joint, may be secondary to diseases commencing in the structuresaround the joint. This affection may therefore follow on a case of acutecoronitis, a case of suppurating corn, a case of quittor, a severe case oftread, or may attend a case of laminitis. 

_Symptoms_. --In our cases we get very little beyond a magnification of suchsymptoms as we have described under acute synovitis. The heat and the painis perhaps greater, and the lameness more marked. It is rather to theconstitutional disturbance we must look, however, for a confirmation of ouropinion that arthritis is in existence. This is always severe, and ofan acute febrile nature. The pulse is fast, thin, and thready, therespirations enormously increased, and the temperature high. The appetiteis in abeyance, the animal quickly becomes what is termed 'tucked-up, ' orgreyhound-like, in the body, and patchy perspirations break out about him. The limb is held with the joints all semiflexed, and severe and intensethrobbing pains are indicated by the frequent pawing movements the animalmakes in the air. Manipulation of the foot is resented, and the agonizingintensity of the pain so caused is shown by the drawn and haggardappearance of the eyes. 

In a favourable case the symptoms from now onwards may gradually subside. The appetite returns, the breathing and other signs of disturbance show areturn to the normal, weight is placed on the limb, and resolution slowlybut surely takes place. In many of these, our favourable cases, however, resolution is incomplete, and recovery only takes place at the expense ofanchylosis of the joint, a condition we shall refer to later. 

In unfavourable cases, and these unfortunately are only too common, thecondition terminates in suppuration. 

(c) PURULENT OR SUPPURATIVE ARTHRITIS. 

_Definition_. --By this term we indicate an arthritis complicated by theformation of pus within the joint. 

_Causes_. --The organisms of pus may infect the joint by extension of asuppurating process from without. For example, in the case of a suppuratingcorn, in quittor, in tread, or in the case of a suppurating wound causedby a prick, the pus formed may in many instances be very near the capsularligament of the articulation. Under such circumstances, unless there is afree and unhindered flow of the pus from an outside opening, inroads willbe made by it upon the thin capsule. The latter is quickly penetrated, andpus is admitted to the interior of the joint. 

In other cases infection of the joint may proceed from within, from apoisoned state of the blood-stream. The condition occurs, for instance, in bad attacks of laminitis. We ourselves, too, have seen two cases wheresuppuration of the pedal articulation occurred in the septic pyæmia offoals, a disease known commonly as 'joint-ill, ' and characterized by aninfected state of the circulation. Cases have also come under our noticewhere this condition has resulted from slight injuries in the region ofthe insertion of the extensor pedis inflicted by the animal himself whengalloping away. 

Perhaps, however, the most common cause of suppurative arthritis in thefoot is direct penetration of the articulation in the case of pricks. The penetrating object is nearly always dirty--bacterially dirty, at anyrate--and suppuration only too readily commences. Even should such a woundbe inflicted by an aseptic body, infection would quickly ensue as a resultof the wound gathering dirt from the ground, or even from admission to thejoint of impure and bacilli-laden air. 

_Symptoms and Diagnosis_. --This is one of the most serious conditions weare called upon to face when dealing with diseases of the foot, for in manycases it quickly ends in exhaustion and death of the patient, while in eventhe most favourable cases nothing better than a condition of complete andbony anchylosis is to be expected. The owner, therefore, should be warnedaccordingly. 

As in the other joint affections, so here, we get all the symptoms ofacute febrile constitutional disturbance. The pulse, the temperature, the respirations, and the general haggard, 'tucked-up, ' and distressedappearances of the animal all tell too plain a tale. Our patient is inconstant pain, and the seat of the trouble is clearly enough shown by theconstant pawing movements of the affected foot. If he has room to get upand down in comfort the animal adopts for long periods at a stretch therecumbent position, and is not upon his legs long enough to take thenecessary amount of food to keep him going. Even when down, it is plain tosee that the animal is not at rest. The pawing movement is still maintainedwith the foot, and every now and again the eyes are opened and the headedlifted to give a troubled look round. The appetite, too, is capricious, andin many cases almost entirely lost. 

In some slight degree the condition is less to be feared in a fore than ina hind foot--that is, so far as absolutely fatal results are concerned. With the condition confined to one fore-foot, the animal is able to get upand down with a moderate degree of comfort. At intervals, therefore, herises to take nourishment, and as soon as his wants are satisfied againlies down. 

With the disease in a hind-foot matters are not taken so comfortably. Thepatient finds that with each day's increasing weakness the difficulty thatat first he had to raise himself with only one sound hind-foot becomesenormously increased. The consequence is that he fears to go down, and thestanding position is maintained until sheer weakness overcomes him, and hegoes down, not to rise again without assistance. 

If judiciously attended he is, of course, put in slings before this stageis reached; but there are instances, as in the case of a cart-mare heavywith foal, where the use of slings is most decidedly contra-indicated. 

If doubt before existed as to the nature of the case, it is at a laterstage dispelled by the appearance, generally in the hollow of the heel, ofa hot and painful swelling. This at first is hard, but later fluctuates. Finally it breaks at one or more spots, and there exudes from the openingor openings a purulent and oftentimes sanious discharge, which coagulatesabout each fistula after the manner of ordinary synovia. 

With the discharge of the abscess contents there is some slight improvementin the symptoms. Here, with a suitable treatment, and with a patient of aparticularly robust constitution, the case appears to turn, and slowly butsurely progresses towards the only end we can hope for--namely, a more orless painless anchylosis of the articulation. 

In less favourable cases the purulent discharge continues, and (always abad sign) becomes more or less chocolate-like in colour, distinctly thin, and stinking. The diseased process spreads until the ligaments of thejoint, both by reason of their infiltration with the inflammatorydischarges, and also on account of the ravages made on them by the invadingpus, either greatly stretch or altogether rupture. 

The joint, after its ligaments have been destroyed in this manner, isloosened, and the bones are now freely movable. Their manipulation givesto the touch a sickening, grating sound--in other words, we have crepitus. This, of course, indicates that the articular cartilages have becomegreatly eroded by the inflammatory process, and so left what we may term'raw' surfaces of bone to rub together. When the animal is put to the walkthe toe of the foot is elevated, and the extreme mobility of the foot givesone the idea of fracture. With every step there is a peculiar suckingnoise, comparable to that of a foot moving in a boot of water, andputrescent matter is squeezed from every opening each time the foot is putto the ground. Although we have seen cases even advanced thus far recover, it is questionable whether it is now wise to attempt to prolong life. Slaughter is far more humane, and, in our opinion, except with a valuablebrood animal, more economical. 

If the animal is allowed to linger, other symptoms will nearly alwayspresent themselves before death occurs. Whether in slings or not, a carefulwatch should be kept upon the sound limb. For some time the patient standsupon it incessantly, but sooner or later it happens that a farther visitshow us the animal standing with full weight on the diseased foot, andmaking painful pawing movements with what before was the sound. Weimmediately jump to the conclusion 'laminitis. ' And so it is, but it is alaminitis brought about by pyæmia. This is indicated by the swollen andoedematous nature of the lymphatics of the limb. Plainly enough theyindicate the road by which the poison has travelled. It is in this way: Pusand putrefactive organisms have gained entrance to the lymphatics ofthe original diseased limb. From these they have rapidly gained theblood-stream and set up infection elsewhere. In this particular instance itis demonstrated by the laminitis and lymphangitis of the previously soundlimb. With the poison thus circulating in the blood-stream, we oftenalso get spots of infection commenced in one or other of the more vitalorgans--notably the lungs or the kidneys. The end of our case is theneither a gangrenous pneumonia or complications induced by a condition ofwidespread pyæmia. 

With the animal in slings there are one or two other symptoms that callfor attention. In many cases, especially with animals of a lymphatic andindolent nature, the use made of them is inordinate. The patient restsso continually in them that alarming swellings commence to make theirappearance about the rectum, or in the case of a mare about the vulva. Theanimal must then be let down at regular intervals and again raised whenrest is obtained. 

A more alarming symptom still is when the animal, instead of resting in theslings by his buttocks, casts his weight bodily into the belly-rest andhangs with a heavy head into the head-stall. This indicates completeexhaustion and a wish for death. Matters should therefore be explained tothe owner, and his consent obtained for immediate destruction. 

_Pathology_. --The pathological changes occurring in suppurative arthritiswe shall pass over briefly. It is almost sufficient, in fact, to say thatthe whole of the joint becomes completely disorganized. 

The synovial membrane becomes so tremendously thickened and injected as tobe scarcely recognisable as such, the thickening in the later stagesbeing due to large growths of granulation tissue which entirely alter theappearance of the membrane as we know it normally. In the early stagesthe contents of the joint are composed of thin pus and synovia. Later, as destruction of the synovial membrane proceeds, the flow of synovia isstopped, while the pus formation goes on until finally nothing but pus anddead tissue products fill the cavity. 

If the suppurative process has commenced from within, the pus that isformed is, as a rule, thick and creamy, comparatively unstained, and freefrom marked odour. If, on the other hand, air has gained access to thejoint, or the suppurative process has started from the materials introducedby a foreign body, the joint contents are thin, blood-stained, andstinking. 

The inflammatory changes in the joint soon spread to the ligaments, and tothe soft structures in contact with them. This means that the ligamentsbecome infiltrated with inflammatory exudate, that the fibrous bundlescomposing them become separated, and that the ligaments are weakened andeasily stretched. As a consequence, a certain amount of displacement ordislocation of the bones is allowed. 

In like manner the inflammatory changes keep spreading until we have theperiosteum next the ends of the bones affected. The periostitis thus setup invariably takes the osteoplastic form, and as a result of this we havegrowths of new bone in the near neighbourhood of the joint. It is in thelater stages of the disease--that is, when the pus has been evacuated andreparative changes commenced--that this osteoplastic periostitis is mostmarked, and it plays a large part in bringing about the condition ofanchylosis, which we shall afterwards describe. 

Grave changes also occur in the articular cartilages. They quickly losetheir peculiar glistening polish, their semitransparency is lost, and thenatural tint of a pearl-like blue gives way to a dirty yellow. Later thisis followed by erosion of the cartilages at such points as they happen tobe in greatest contact. The ends of the bones are thus exposed, and theirmedullary cavities exposed to infection. As a result we get in them thechanges we have already described under Ostitis. 

_Treatment_--_(a) Preventive_. --Seeing that many of these cases have theirstarting-point in stabs or penetrating wounds of the sole, we shall beconcerned first with a consideration of the correct treatment to be adoptedwhen we know the wound to have reached the articulation. 

Only too frequently the treatment practised is that of poulticing. In otherportions of this work we have pointed out the advantages that a continuedantiseptic bathing has over the application of a poultice, the greaterreadiness with which the solution comes into contact with the deeper partsof the wound, and the far greater chance there is of maintaining water inan antiseptic condition than there is of keeping a poultice in the samestate. There is no doubt, that in this case also, the cold or warmantiseptic bath is to be preferred to the poultice. It is questionable, however, whether even the bath is sufficient for our purpose here. We havein this case a deep punctured wound, and a wound that in every probabilityis infected with the organisms of pus or of putrefaction. It is a wound, moreover, which is likely to impede the thorough access to it of thesolution in which the foot is fomented, on account of the flakes ofcoagulated fibrin which fill it. 

The most rational treatment, therefore, if we get to the case early enough, is to irrigate the wound freely with a solution of carbolic acid in water(1 in 20), or with a solution of perchloride of mercury (1 in 1, 000), injected by means of a glass syringe, or the pattern of syringe devised forquittor. This injecting should be done thoroughly, and by that we mean thatseveral syringefuls of the solution should be injected, the joint aftereach injection being manipulated so as to distribute the solution as far aspossible over it. When this is done the opening in the sole may be pluggedwith a little perchloride of mercury, or, better still, with a little pieceof tow saturated with a concentrated solution of perchloride of mercuryor a solution of iodoform in alcohol and an antiseptic pad of tow or lintplaced over all. The foot should then be bandaged and encased in a boot orsacking protective. The bandage should be removed daily and the antisepticpad changed. At each visit the animal's condition must be carefullynoted. So long as constitutional disturbance is slight, the foot appearscomfortable, is free from marked heat and tenderness, and pawing movementsare absent, and so long as the discharge on the pad appears non-purulent, free from marked odour, and small in quantity, then this dressing may bepersisted in. 

This treatment of open joint, preventive as it is of arthritis, is alsoindicated in the case of open navicular bursa. In several instances we havepractised this treatment for the dressing of wounds implicating the bursæof tendons and the capsules of joints. It is also spoken of favourably byMr. C. H. Flynn in the _American Veterinary Review_ for June, 1888, whosetreatment is as follows: 'Place the patient in a clean, well-ventilated, and drained stable. Have all the litter removed, and insist on the stallbeing kept clean. Either place the animal in slings, or tie the head so asto prevent lying down. Clip the hair and cleanse the parts well. He prefersthe corrosive sublimate solution (1 in 1, 000). Should the wound be of twoor more days' standing, inject the joint with the corrosive sublimatesolution. Now dry the parts with a clean towel and sprinkle the wound withiodoform. Over this place a thick layer of absorbent cotton-wool, filledwith iodoform, bandage securely, and keep the patient on a moderate diet, preserving the utmost quietude possible. Should the bandage remain inposition and the animal free from pain, leave the bandage and dressing inplace from five days to a week. Then change it, and should the dischargebe little, do not disturb it, but renew the iodoform and cotton dressing, leaving it on for another week. '

Other treatments for the same condition are practised, in which the woundis dusted with powdered iodoform, with potassium permanganate, or withcorrosive sublimate, or where the wound, instead of being dusted, hasthe corrosive sublimate applied in the form of a plug. In each case thepreliminary irrigation with the corrosive sublimate solution is dispensedwith. This, however, should on no account be omitted. In our opinion itconstitutes the very essence of the rationality of the treatment. 

_(b) Curative_. --It may happen, however, and often does, that this firstinjection of an antiseptic is unsuccessful in preventing organismalinfection of the wound. In this case grave constitutional disturbance andother untoward symptoms such as we have already described quickly maketheir appearance. 

The animal should now be placed in slings and preparations made foractively treating the wound with antiseptics. Whether we fail or not, wehave the satisfaction of knowing that we have given to the patient the bestand the only chance of recovery. 

It should be remembered, however, and should be pointed out to the owner, that with purulent arthritis fully developed, with the grave constitutionalchanges it occasions, and with the ever-present danger of a generalseptic invasion of the blood-stream, that the human surgeon under suchcircumstances offers to his patient the alternatives of amputation orprobable death. With us no such alternative is possible. It is eitherreturn the joint to some semblance of its former usefulness, or destroy thepatient. 

In this case we advise the injection of the original wound, and also suchfistulous openings as may have formed, with the 1 in 1, 000 sublimatesolution. Also, in order to avoid the sometimes abortive attempts of theantiseptic pad, to maintain a condition of asepsis around the wound, weadvise the continual soaking of the whole foot in a cold antiseptic bath. This may be either carbolic acid 1 in 20, or--what is less volatile, perhaps more effectual, and certainly more economical--perchloride ofmercury 1 in 1, 000. 

It has been our good fortune, even when we have seen the foot almostdetached from the limb by the devastating inroads of the pus, to seethe suppurative process by this means gradually overcome, a reparativeanchylosis set in, and the animal restored to good health and usefulness, if not to soundness. 

Once the suppurative process is checked and anchylosis commences, it isgood treatment to smartly blister the whole of the region of the coronet, the pastern, and the wound itself with a mixed blister of cantharides andbiniodide of mercury, repeated at intervals of a fortnight. This preventsto some extent further infection of the wound, and assists also inpromoting the changes that tend to anchylosis. 

_(d)_ ANCHYLOSIS. 

The word anchylosis signifies the stiffening of a joint. When one has readthe serious changes occurring within the joint in the more serious formsof arthritis, it is easy to understand how it comes about. In suppurativearthritis, for instance, we have the synovial membrane destroyed, thearticular cartilages partly or wholly obliterated, and the formerboundaries of the joint entirely lost. If the animal lives, nature isbound to make repair of a sort. The synovial membrane and the articularcartilages utterly destroyed, as we have described, cannot again bereplaced. Nature can only build again from such materials as are left toher. In this case the material is bone. 

It must be remembered, however, that often the bone has been so diseasedthat spots of necrosis or caries within it are bound to remain unless movedby operative interference. Such diseased portions, when dealing with thefoot, are beyond reach of the surgeon's knife, and we have no alternativebut to allow them to remain. We get, therefore, in many cases, a conditionof rarefactive ostitis occurring side by side with a slowly progressivecaries within the bone, while outside is occurring an osteoplasticperiostitis. The concurrence of these conditions leads in time to greatincrease in size of the parts, together with increasing anchylosis anddeformity. 

C. NAVICULAR DISEASE. 

_Definition_. --Chronic inflammatory changes occurring in connection withthe navicular bursa, affecting variously the bursa itself, the perforanstendon, or the navicular bone, and characterized by changes in the formof the hoof and persisting lameness. The disease is commonly noticedin thoroughbreds or in horses of the lighter breeds, and is but seldomobserved in heavy cart animals. Usually it is met with in one or bothfore-feet. Although of extremely rare occurrence, it has been noticed inthe hind. 

_History_. --To English veterinarians appears to belong the credit ofdiscovering navicular disease. As early as 1752 we find one, JeremiahBridges, in 'No Foot, No Horse, ' drawing attention to 'coffin-jointlameness, ' and advocating for its treatment setoning of the frog. Itappears, too, that Moorcroft, prior to his departure for India in 1808, wasacquainted with what was then known as coffin-joint[A] lameness, havingdrawn attention to it in 1804 in a letter to Sir Edward Codrington. [B] In1819 Moorcroft made it even plainer still that he was fully acquainted withwhat we now know as navicular disease. This we learn from a letter writtenby him to Sewell, in which he laid claim to being the originator ofneurectomy. In this letter he says:

[Footnote A: The coffin-joint at this time included the navicular bursa. ]

[Footnote B: Percival's 'Hippopathology, ' vol. Iv. , p. 132. ]

'On dissecting feet affected with these lamenesses, the flexor tendon wasnow and then observed to have been broken, partially or entirely, butmore commonly to have been bruised and inflamed in its course under thenavicular or shuttle bone, or at its insertion into the bone of the foot. Sometimes, although seldom, the navicular bone itself has been found tohave been fractured; at others its surface has been deprived of its usualcoating, and studded with projecting points or ridges of new growth, orexhibiting superficial excavations more or less extensive. '[A]

[Footnote A: _Ibid_. ]

_Pathology and Point of Commencement of the Disease_. --The exact positionin which the diseased process starts has for a long time been a subjectof discussion, and even now it is doubtful whether the point has beendefinitely settled. To mention but a few among many: We find Mr. Broad, ofBath, strenuously insisting on the fact that the disease commences in theinterior of the navicular bone. Just as strenuously we find the editor ofthe journal in which the matter is being discussed, the late Mr. Fleming, asserting that the disease commences in the bursa. [A] Others, too, holdthat the disease commences primarily in the tendon. Wedded to this view wasthe discoverer, Mr. Turner, of Croydon; while Percival commits himself tothe statement that it is either the central ridge or the postero-inferiorsurface of the navicular bone, or the opposed concavity in the perforanstendon, that shows the earliest signs of the disease. The observations madeby Dr. Brauell, the first Continental writer to fully describe the disease, led him to the statement that neither the bone nor the bursa was the_invariable_ starting-point of the trouble, but that usually it commencedin inflammation of the bursa itself. 

[Footnote A: Percival's 'Hippopathology, ' vol. Iv. , p. 132. ]

Without, therefore, committing ourselves to an expression of opinion asto the precise starting-point of the affection, we shall describe thepathological changes occurring in navicular disease as noted in (1) thebursa, (2) the cartilage, (3) the tendon, and (4) the bone. 

1. _Changes in the Bursa_. --Upon the internal surface of the bursalmembrane is first noticed a slight inflammatory hyperæmia, accompaniedby more or less swelling and tumefaction, owing to its infiltration withinflammatory exudate. The portion covering the hyaline cartilage of thenavicular bone has lost its peculiar pearl-blue shimmer, and become a dirtyyellow. 

Remembering that the bursal membrane is a synovia-secreting one, andbearing in mind what happens in ordinary synovitis and arthritis (withwhich, of course, this may be very closely compared), we shall first expectchanges in the bursal contents. It is highly probable, though difficult ofproof, that in the very early stages the chronic inflammatory stimulus hasthe effect of increasing the flow of synovia. In every case, however, whereit can with any certainty be said that navicular disease exists, it is toolate to meet with this condition. The disease has then progressed untildestruction of the secreting layer of the bursal membrane has beenseriously interfered with, and in this case we find a distinct deficiencyin the quantity of synovia in the bursa. In advanced cases it is even foundthat the bursa is _absolutely dry_. 

2. _Changes in the Cartilage_. --Directly that portion of the bursalmembrane covering the cartilage is the subject of inflammatory change, thecartilage itself, by reason of its low vitality, soon suffers. 

Under a process, which we may term 'dry ulcerative, ' the cartilage coveringthe ridge on the lower surface of the bone commences to become eroded, andin appearance has been likened, both by English and Continental writers, toa piece of wood that has been worm-eaten (see Fig. 161). 

[Illustration: FIG. 161. --NAVICULAR BONE (POSTERO-INFERIOR SURFACE) SHOWINGTHE 'WORM-EATEN' APPEARANCE CAUSED BY EROSION OF THE HYALINE CARTILAGE, ANDCOMMENCING RAREFACTIVE ARTHRITIS. ]

'At this stage, or much earlier'--we are quoting Colonel Smith, A. V. D. --'may be found calcareous deposits in the fibro-cartilage and thebone. They are scattered like fine sand here and there, generally acrossthe inferior half of the face of the bone; they are sometimes numerous, frequently scanty, occasionally entirely absent. The amount of calcareousdegeneration depends upon the lesions present. If much destruction of boneexists, there will be but few calcareous deposits; whilst if there are manycalcareous deposits, there may be but slight ulceration of bone tissue, andperhaps none at all. In fact, I have held the opinion, and see no reason tomodify it, that calcareous deposits are safeguards against caries. '[A]

[Footnote A: _Journal of Comparative Pathology and Therapeutics_, vol. Vi. , p. 195. ]

3. _Changes in the Tendon_. --The effect of these calcareous deposits onthe under surface of the bone is to produce a certain amount of roughness. Seeing that with every movement of the foot the perforans tendon is calledupon to glide over this surface, it is clear that a secondary effect mustbe that of inducing erosion and destruction of the tendon. The point atwhich this usually commences is at the bottom of the depression thataccommodates the ridge on the bone. With erosion of the cartilage and ofthe tendon at points exactly opposite each other, we have two surfaces cometogether that are prone to readily unite, and fibrous tissue adhesionsoften take place between the bone and the tendon. In some measure thisaccounts for the torn and ragged appearance of the tendon. Adhesions takeplace, and, under some small strain, are broken down. This may happen morethan once or twice, and with each breaking of the adhesion between the boneand tendon, fibres from the latter are lacerated and torn from their place(see Fig. 162). 

4. _Changes in the Bone_. --The changes occurring in the bone areessentially those of a rarefactive ostitis. These changes are described bymany writers, and, whether originating primarily in the bone or not, itseems certain that extensive changes may have occurred within the bone, with but little or nothing to be noted on its outer surface. It would seemthat the first change is one of congestion of the vessels of the bone'scancellous tissue. With the cause, whatever it may be, in constantoperation, the congestion persists until a low type of inflammation is setup, interfering, not only with the flow of synovia in the adjoining bursa, but with the nutrition of the bone itself. As the disease progresses, thereis softening and enlarging of the cancellated tissue towards the centreof the bone. The cells break up, and absorption takes place. This goes onuntil a large portion of the interior of the bone is in a state of drynecrosis, with, in many cases, but slight signs of mischief on the exteriorof the bone. 

In other cases, however, the changes in the interior of the bone areaccompanied by well-marked lesions on its gliding or postero-inferiorsurface, and by evidences of an osteoplastic periostitis along its edges. 

That an osteoplastic periostitis has been in existence is witnessed by theappearance along the edges of the bone of numerous outgrowths of bone, termed osteophytes (see Fig. 163). 

[Illustration: FIG. 162. --A FOOT WITH THE SEAT OF NAVICULAR DISEASEEXPOSED. On the anterior surface of the perforans fibres of the tendon areseen to be torn away from their abnormal adhesion with the navicular bone, while others are seen to be still attached thereto. The surface of thenavicular bone itself exhibits small defects in the bony substance, whichhave been brought about by a rarefactive ostitis. _a_, The perforans tendoncut through and reflected; _b_, the sole. ]

The interosseous and postero-lateral ligaments of the articulationoften participate in the inflammatory changes, and in many cases becomecompletely ossified. The true articulatory surface of the bone, thatarticulating with the os pedis and with the os coronæ, is never affected. 

_Causes_. --In enumerating the causes of navicular disease, we shallfollow the example of Colonel Smith and classify them under certainheadings--namely, (1) _Hereditary Predisposition_; (2) _Compression_; (3)_Concussion_; (4) _A Weak Navicular Bone_; (5) _A Defective or IrregularBlood-supply to the Bone_; and (6) _Senile Decay_. 

[Illustration: FIG. 163. --THE NAVICULAR BONE FROM A CASE OF LONG-STANDINGNAVICULAR DISEASE. The erosion of the cartilage on its central ridge ismost marked, and the porous appearance of the bone thus uncovered pointsto the existence within it of a rarefactive ostitis. Along its edgeslarge osteophytic outgrowths speak of the effects of an osteoplasticperiostitis. ]

1. _Hereditary Predisposition_. --That navicular disease is hereditary isa fact that has for a long time been insisted on, and has come to be sogenerally admitted that we do not intend to dwell on it here. As we havesaid before, it is found in the lighter breeds of horses (and, accordingto Zundel, especially in the English breeds), and is there seen to befrequently transmitted from parent to offspring. 

2. _Compression_. --By this is meant the compression of the navicular bonebetween the os pedis and the os coronæ in front, and the perforans tendonbehind. 

In order to appreciate this explanation of the causation of naviculardisease at its true value, it will be well to consider briefly thephysiology of the parts in question. 

The navicular bone is what we may term a complement of the os pedis. Itexists, in fact, simply in order that the os coronæ may have a sufficientlylarge articulatory surface to play upon. One wonders at first that Naturedid not arrive at this by originally placing a larger bone below. ColonelSmith explains this by suggesting that this would in all probability havemeant its fracture. In progression the hind part of the foot comes to theground first, and upon the hinder portion of the articulation would fallthe first effects of concussion, together with the greater part of thebody-weight. A yielding joint was in this position necessary, and thatformed by the navicular bone fills all requirements. 

In this connection one next considers the part played by the front limbsduring progression. As Zundel expresses it, they are columns of supportrather than of impulsion, and, as the body-weight is thrown forward by thehind-limbs, it is the duty of the fore-limbs to receive it. The shock orconcussion of the body-weight thus thrown forwards is first received bythe muscles uniting the limb to the trunk, and a great part of it thereminimized by their sling-like attachment. It is further absorbed by theshoulder-joint, and from there passed on to the almost vertical bony columnrepresented by the radius and ulna, the knee, and the metacarpus. Onreaching the first phalanx, a portion of the remaining force is passed onto the front of the phalanges and loses itself in front of the hoof, whilethe other portion is transmitted to the flexor tendons, finally to theperforans, and to the posterior parts of the foot. During progression, therefore, the navicular bone is constantly pushed downwards and backwardsby the bony column, and is just as constantly pushed forwards and upwardsby the resistance of the perforans tendon. This means, of course, thatthe navicular bone is more or less constantly subject to compression, and constant pressure, as we know full well, is a pretty sure factorin bringing about malnutrition of the parts, with atrophy or chronicinflammatory changes as an end result. 

Even with the limb at rest the pressure on both sides of the navicular boneis still constant. The only circumstances under which we can conceive ofit being entirely absent, in fact, are when the tension on the tendon isrelaxed, and the body-weight altogether removed by the animal adopting therecumbent position. 

The compression theory as to the causation of navicular disease was, webelieve, first originated by Colonel Smith. He, at any rate, has laid muchstress on it in his writings. If we accept it, and we see every reasonthat we should, then we must, with the author, admit the possibility ofnavicular disease arising from long standing in one position. 

3. _Concussion_. --This we are bound to admit as a cause, and in so doingpartly explain the comparative, almost total, immunity of the hind-feetfrom the disease. The fore-limbs, as we have already pointed out, arelittle more than props of support, and the force of the propelledbody-weight is transmitted largely down their almost vertical lines, toend largely in concussion in the foot. With the hind-limbs matters aredifferent. 'These, ' as Percival explains it, 'have their bones obliquelyplaced, so as to constitute, one with the other, so many obtuse angles, tothe end, that by forming powerful levers, and affording every advantage foraction to the muscles attached to them, they may be fitted for the purposeof propulsion of the body onward. '

The effect of these several obtuse-angled joints in the limb is to absorbthe greater part of the force exerted by the body-weight before it reachesthe foot. When with this we take the facts that the fore-limbs have tocarry the head and neck, and that they have to bear this added weight, plusa propelling force from behind, we see why it is that they should be sosubject to the disease, and the hind-limbs so exempt. 

As pointing out the part that concussion plays in its causation, we maymention that navicular disease is a disease of the middle-aged and theworked animal. It is interesting to note, too, that it occurs in animalswith well developed frogs--in feet in which frog-pressure with the groundis most marked. This at first sight appears to flatly contradict what wehave said with regard to frog-pressure in other portions of this work. Withthis, however, must be reckoned other predisposing causes. In this case itis not to frog-pressure alone we must look, but to the condition of thefrog itself, and that of the neighbouring parts. It is when we have a frogwhich, though well developed and apparently satisfying all demands asto size and build, is at the same time composed of a hard, dry, andnon-yielding horn that we must look for trouble. 

The foot predisposed to navicular disease is the strong, round, short-toedor clubby foot, open at the heels, with a sound frog jutting prominentlyout between them. Here is a frog exposed to all the pressure that mightbe desired for it, bounded at its sides by heels thick and strong, andindisposed to yield, and itself liable, from its very exposure, to become, in the warm stable, hard and dry, and incompressible' (Percival). 

Here, instead of acting, as normally it should, as a resilient body, and anaid to the absorption of concussion, it seems rather to play the part ofa foreign body, and to bring concussion about. Seeing, then, that thenavicular bursa is in very near contact with it, it is conceivable thatthis joint-like apparatus should suffer, and the pedal articulation be leftunaffected, the more so when we take into consideration the compressiontheory just described. 

4. _A Weak Navicular Bone_. --When the disease commences first in thebone--and there is no denying the fact that sometimes, although notinvariably, it does--it may be explained by attributing to the structure ofthe bone an abnormal weakness in build. 

The navicular bone consists normally of compact and cancellated tissuearranged in certain proportions, the compact tissue without, and thecancellated within. These proportions can only be judged of by theexaminations of sections of the bone, and when it is found in any case thatthe cancellated tissue bulks more largely in the formation of the bone thannormally it should, we have what we may term a weak navicular bone. In thisconnection Colonel Smith says: 'Though it is far from present in every caseof the disease, still I consider it a factor of great importance. '

5. _A Defective or Irregular Blood-supply to the Bone_. --This, ColonelSmith considers, is brought about by excessive and irregular work, and bythe opposite condition--rest. The author points out that the bloodvesselspassing to and from the navicular bone run in the substance of theinterosseous ligaments, or in such proximity to them that it is conceivablethat under certain circumstances mechanical interference may occur to thenavicular circulation. He further points out a fact that is, of course, well known to every veterinarian, that in periods of work the circulationof the foot is hurried, and that in rest there is always a tendency tocongestion; and he says in conclusion: 'I cannot help thinking thatirregularities in the blood-supply in a naturally weak bone must be afactor of some importance, especially when the kind of work the horse isperforming is a series of vigorous efforts followed by rest. '

6. _Senile Decay_. --With approaching age the various tissues lose theirvigour, and are prone to disease. The navicular bone and surroundingstructures are not exempt. With the other and more active causes we havedescribed acting at the same time it is not surprising that naviculardisease is seen as a result. 

In conclusion, it is well, perhaps, to say that, no matter to whichparticular theory of causation we may lean, we should make up our minds toconsider them as a whole. While one cause may be exciting, the other maybe predisposing, and the two must act together before evil results arenoticed. It may be that even more than two are concerned in bringing on thedisease, and to each the careful veterinarian will give due consideration. 

_Symptoms and Diagnosis_. --In the early stages of navicular disease thesymptoms are obscure. Pointing of the affected limb is the first evidencethe animal gives. This, however, more often than not, goes unnoticed, and the first symptom usually observed by the owner or attendant is thelameness. Even this is such as to at first occasion no alarm, beingintermittent and slight, and only very gradually becoming marked. In a fewcases, however, lameness will come on suddenly, and is excessive from thecommencement. It is the lameness, slow in its onset, intermittent inits character, and gradual in its progress, however, that is ordinarilycharacteristic of navicular disease. 

The animal is taken out from the stable sound, with just a vague suspicion, perhaps, that he moved a bit stiffly. While out he is thought by his driveror rider to be going feelingly with one foot or with both. Even this is notmarked, and the driver has some difficulty in assuring himself whether orno he really observed it, or whether it was but imagination. 

On the return home the limb is examined, and nothing abnormal is to befound. The leg is of its normal appearance, and neither heat nor tendernessis to be observed in it or in the foot. On the following day the animalagain is sound, and the lameness of the previous day is put down to aslight strain or something equally simple. The patient is then, perhaps, rested for a day or two. When next he is worked he again moves out from thestable sound, but again during the going gives the driver the unpleasantimpression that something is amiss; and so the case goes on. One day theowner fears the animal is becoming seriously enough affected to warrant himin calling in his veterinary surgeon; the next he is confidently assuringhimself that nothing is wrong. 

Perhaps the animal is now rested for a week or two, or even for a month ortwo, hoping that this will put him sound. Immediately on commencing work, however, the same symptoms as before assert themselves, and the veterinarysurgeon is called in. 

With a history such as we have given the veterinarian's suspicions arearoused. He has the animal trotted, and may notice at this stage that thereis an inclination to go on the toes, that the lame limb or limbs are notput forward freely, and that progression is stilty and uncertain; itis such, in fact, as to at once suggest the possibility of corns beingpresent. 

In some cases there is just the suspicion of a limp with one limb, andthis only at intervals during the trot. At one moment the veterinarianis positive that he sees the animal going lame; at another he is just asconfident he sees him coming towards him sound. 

Nothing is found in the limb--neither heat, tenderness, nor swelling. Thereis nothing in the gait (either a limited movement of the radius, or acircular sweep with the leg) to indicate shoulder or other lameness, andthe veterinary surgeon, by eliminative evidence, is bound to conclude thatthe trouble is in the foot. 

The foot is then examined--pared, percussed, pinched, and in other waysmanipulated--but nothing further is forthcoming. In such a case theveterinary surgeon is wise to declare the abortive result of hisexamination, to hint darkly of his suspicions, and to suggest a secondexamination at some future date. It may be that two, three, four, or evenmore, such examinations are necessary before he can justly pronounce apositive verdict. 

Later he is enabled to do this by an increase in the severity of thesymptoms, and by the changes that take place in the form of the foot. The lameness is now more marked, and the 'pointing' in the stable morefrequent. With regard to the latter symptom, it has been seriouslydiscussed whether the horse with navicular disease points with the heelelevated or with it pressed to the ground. In either case, of course, thelimb is advanced; but while some hold that the phalangeal articulations areflexed and the heel slightly raised, in order to relieve the pressure ofthe perforans tendon on the affected area, and so obtain ease, there areothers who hold that the heel is pressed firmly to the ground in order todeaden the pain. It may be, and most probably is, that both are right; but, in our opinion, there is no doubt whatever that pointing with the heelelevated is by far the most common. 

The lameness is now excessive, and is especially noticeable when the animalis put to work on a rough or on a hard ground. Even now, however, heat ofthe foot or tenderness is so slight as to be out of all proportion to thealteration in gait. 

With the case thus far advanced, evidence of pain may be obtained bypressing with the thumb in the hollow of the heel. Evidence of pain mayalso be obtained by using the farrier's pincers on the frog. These methods, however, are never wholly satisfactory, as a horse with the soundest offeet will sometimes flinch under these manipulations. 

Extreme and forcible flexion of the corono-pedal articulation alsosometimes gives evidence of tenderness. In this case the foot is held up, the animal's metacarpus resting on the operator's knee, and the toe of thehoof pushed downwards with some degree of force. 

The same movement of the joint is given by causing the animal to put fullweight upon the diseased limb, a small wedge of wood being first placedunder the toe. In this manner the pressure of the perforans tendon upon thebursa is greatly increased, and the animal is caused to show symptoms ofdistress. 

The lameness may also be increased, and diagnosis helped, by paringthe heels, so as to leave the frog prominent and take the whole of thebody-weight. The same end is also obtained by applying a bar shoe. This wasoriginally pointed out by Brauell, and is quoted by Zundel and by Möller. 

The changes in the form of the hoof may now be noticed. These are largelydependent on the fact that more or less constantly the patient saves theheel. The horn of the walls in this region, and the horn of the frog, is thereby put out of action and induced to atrophy. The hoof graduallyassumes a more upright shape, and the heels contract. We thus get a hoofwhich is visibly narrowed from side to side, with a frog that is atrophiedand often thrushy, and with a sole that is abnormally concave, hard, andaffected with corns. 

When occurring in the hind-feet--a condition that is rare, but which hasbeen noticed by Loiset, and quoted by Zundel--the animal is stiff behind, walks on his toes, and gives one the impression that he is suffering fromsome affection in the region of the loins. 

One such case is reported by an English veterinary surgeon, and we quote ithere:

'A gray gelding, and a capital hunter, the property of a gentleman in thisneighbourhood, became lame in the near fore-foot after the hunting seasonof 1859. The lameness was believed to be due to navicular disease. The operation of neurectomy was ultimately had recourse to. The horsesubsequently did his work as well as ever, and was ridden to houndsregularly till the end of the year 1861, when he went lame of the offfore-foot. From this date he also showed very peculiar action behind, andwas at times lame of both hind-limbs without any apparent cause. 

'In the year 1862, from the groom's indiscreet use of physic, superpurgation was brought on which caused the animal's death. On apost-mortem examination being made, the horse was found to have _naviculardisease of all four feet_. It is worthy of note that this horse hadalways "extravagant" action behind, but was a remarkably quick and goodjumper. '[A]

[Footnote A: F. Blakeway, M. R. C. V. S. , _Veterinarian_, vol. Ii. , p. 21. ]

_Differential Diagnosis_. --Navicular disease may be mistaken for ordinarycontracted foot. It will be remembered, however, that in the early stagesof navicular disease contraction is absent, and that it is only when thedisease in the bursa is of long standing that contraction comes on. Withordinary contracted foot, too, careful paring and suitable shoeing soonsees a diminution in the degree of lameness, and a return to the normal inshape (see Treatment of Contracted Foot, p. 125). With navicular disease, however, such shoeing as is beneficial in the treatment of contracted foot(notably the various methods of giving to the frog counter-pressure withground) soon brings on an aggravation of the lameness. 

It is, perhaps, even more likely to be confounded with contraction when wehave with the contraction a state of atrophy and thrush of the frog. Witha frog in this condition pressure will give rise to pain, and naviculardisease be erroneously judged to be present. In such a case we must relywholly upon either extreme flexion or extreme extension of the joint toguide us, when, if contraction _only_ is the offending condition, nosymptom of pain will be shown. 

Navicular disease may also be confused with rheumatic affections, with sprain of the posterior ligaments of the first interphalangealarticulation, and with sesamoid lameness. Mistakes are sometimes made, too, especially with a hasty observer, in confounding it with shoulder lameness. 

In rheumatism the constant changing of the seat of pain, the sometimeselevated temperature, and the appearance of symptoms of heat, tenderness, and swelling in the affected area should guide one to a right conclusion. 

In sprain of the posterior ligaments of the coronet and in sesamoidlameness, nothing but a careful examination and manipulation of the partswill ward off error, for in each of these cases there is 'pointing' andresting of the limb, and considerable disinclination to put weight firmlyupon it. If at the same time manipulation gives distinct evidence of pain, all doubt may be set at rest. 

Roughly speaking, sesamoid lameness is a condition of the gliding surfaceof the sesamoids, and the face of the tendon playing over them, similar tothat found in navicular disease. All symptoms of pointing, the constantmaintaining of the limb in a state of flexion, and a feeling manner ofprogression are again all present. It is plain from this that in all caseswhere an animal with a gait at all suggestive of navicular disease isbrought for our examination, the manipulation of the limb should bethorough. The character of the lameness is almost sure to deceive us; andit is not until we are able to obtain local symptoms pointing to the one orthe other of the conditions we have enumerated that a decisive opinion maybe given. In sesamoid lameness the local symptoms are those of heat andpain in the fetlock on palpation, and a swelling of the affected parts, such swelling being at first slight, yielding, and barely distinguishable, and afterwards larger, bony and hard, and more marked. Later still there isdistinct evidence of 'knuckling' over at the fetlock and inability to fullyflex it. 

In cases of shoulder lameness the gait alone should be sufficient to renderliability of error small, for with nearly every case there is a manifestinability to 'get the limb forward', and this is best seen at a side viewwhen the animal is trotting past the observer. When trotting towardsone, there is a further and unmistakable symptom common to most shoulderlamenesses that serves to distinguish it at once, and that is the peculiar'sweeping' outwards with the affected limb. 

Lastly, with either of the conditions we have just mentioned, it is theexception to get contracted foot follow on. With navicular disease itsooner or later makes its appearance. 

_Prognosis_. --The prognosis of navicular disease (once diagnosed withcertainty) must almost of necessity be unfavourable. The facts that thedisease has made serious progress before it is really noticeable, thatthe situation of the parts prohibits operative interference, and that thedisease is one of a chronic and slowly progressive type, all point to anunfavourable termination. 

_Treatment_. --We have seen from the pathology of this disease that it maycommence either as a rarefactive ostitis, or as a synovitis and tenositisin connection with the bursa. With the former condition in existence, orwhen this and the synovitis has led to erosion of the cartilage, treatmentis probably of no avail, on account of the more chronic nature of these twoconditions. When, however, the condition is simply that of synovitis ortenositis, a more or less acute condition, we may assume that suitabletreatment and a long rest will bring about resolution. 

The first indications in treatment are those of what we may term 'nursing'the foot. It should have sufficient rest, should be placed so as tominimize as far as possible compression of the parts, and should haveits posterior half treated so as to render it softer and less liable toconcussion. 

The period of rest required cannot be satisfactorily advised, and thepractitioner is wise who makes it a long one. Best should be advised, infact, long after symptoms of lameness have disappeared and recovery isjudged to have taken place. 

Compression of the parts may be somewhat minimized, if the animal be keptin the stable, by allowing the floor upon which the front-feet are to standto be slightly sloping from behind forwards. The same effect, though not somarked, is obtained by removing the shoes, and considerably lowering thewall at the toe, while allowing that of the heels to remain. It may here beremarked that it is a good practice to allow the shoes to remain on, andthis even when the animal is at grass. They should, however, be frequentlyremoved, and the foot trimmed as we have directed. 

With the foot thus trimmed so as to most suitably adjust the angles ofthe articulations, it should next be thoroughly pared and rasped in itsposterior half, so as to render the horn of the sole and the frog and thehorn of the quarters as thin as possible. The heels, however, should not beexcessively lowered, _if at all_. We now have the foot in a soft condition, and easily expanded. It should, if possible, be kept so; and this may bedone either by the use of poultices, by tepid baths, or by standing theanimal upon a bedding that may easily be kept constantly damp. Suchmaterials as tan, peat moss, or sawdust, are either of them suitable. 

All this, of course, calls for keeping the animal in the stable. It is farbetter, however, more especially if a piece of marshy land is at hand, toturn him out in that. A moderate amount of exercise is beneficial ratherthan not, and the feet are thus constantly kept damp without trouble to theattendants. 

The second indication in the treatment is that of applying acounter-irritant as near to the diseased parts as possible. Regarding itsefficacy we must confess to being somewhat sceptical. The treatment hasbeen constantly practised and advised, however, and we feel bound to giveit mention here. A smart blister may, therefore, be applied to the whole ofthe coronet, and need not be prevented from running into the hollow of theheel. 

Instead of blistering the coronet (or in conjunction with that treatment), the counter-irritant may be applied by passing a seton through the plantarcushion or fibro-fatty frog. Setoning the frog appears to have beenintroduced by Sewell. In many cases great benefit is claimed to have beenderived from it, especially by English veterinarians of Sewell's time, andby others on the Continent. Percival, however, was not an advocate for it, and, at the present day, it is a practice which appears to have dropped outof use altogether. 

[Illustration: FIG. 164. --FROG SETON NEEDLE. ]

To perform this operation a seton needle of a curved pattern is needed(see Fig. 164). This is threaded with a piece of stout tape dressed with acantharides, hellebore, or other blistering ointment, and then passed in atthe hollow of the heel, emerging at the point of the frog. The course theneedle should take will be understood from a reference to Fig. 165. 

The seton may be passed with the horse in the standing position. Previouslythe point of the frog should be thinned, and the animal should be twitched. After-treatment consists simply in moving the seton daily, and dressing itoccasionally with any stimulating ointment, or with turpentine. 

If, in spite of these treatments, the disease persists, then nothingremains but neurectomy. 

D. DISLOCATIONS. 

The firm and rigid manner in which the bones of the pedal articulationare held together renders dislocation of this joint an exceedingly rareoccurrence, and then it is only liable to happen under the operation ofgreat force. In the literature to our hand we have only been successfulin discovering one reported instance, and, strange to say, in this, awell-marked case, the cause was altogether obscure. We quote the case atthe end of this section. 

[Illustration: FIG. 165. --DIAGRAM SHOWING THE COURSE TAKEN BY THE NEEDLEWHEN SETONING THE FROG. This is shown by the dotted curved line _a, b_. 1, The navicular bone; 2, the plantar cushion; 3, the os pedis; 4, theperforans tendon. ]

A partial dislocation of this articulation is the condition met with in'Buttress Foot. ' In this case the fracture of the pyramidal process, andthe consequent lengthening of the tendon of the extensor pedis, allows theos coronæ to occupy upon the articulatory surface of the os pedis a morebackward position than normally it should. 

It is quite probable, too, that slight lesions of the other restrainingligaments and tendons of the articulation may bring about a similar thoughless marked condition. We may be quite sure of this--that whenever suchlesions (as, for example, sprain and partial rupture of the lateralligaments) do occur, and the normal position of the opposing bones ischanged, if only slightly, that great pain and excessive lameness must bethe result, and this with but little to show in the foot. Many of our casesof obscure foot lameness might, if capable of demonstration, turn out to becases of sprain and partial dislocation of the pedal articulation. 

_Recorded Case_. --'The animal, a trooper of the 8th Hussars, was found onthe morning of April 17 unable to bear any weight on the limb (thenear hind). Cause not known--the heel-rope I thought at first; but oninvestigation I found the heel-rope had been on the other leg. 

_Diagnosis_. --Dislocation of the left os coronæ from the articulatingsurface of the os pedis in a backward direction. 

'Every devisable means were unsuccessful in reducing the limb to itsnatural position. The horse was thrown, and a strong rope, with four menpulling at it, was fastened round the hoof, whilst I put my knee to theback of the pastern, using all possible force, with one hand to the footand the other to the fetlock, but all to no purpose. Next day other meanswere tried. First by throwing the horse and placing him on his belly, withthe fore-legs stretched out forwards, and the hind-legs backwards. This Idid so as to get the injured limb placed as nearly flat on the ground aspossible, with its anterior aspect downwards. Then a very heavy man, withhis boots off, was made to jump on the back of the pastern, where theprominence showed most; and afterwards, when these means failed, a strongpiece of wood, well covered with leather, was placed (where the hollow ofthe heel ought to have been) on the most prominent part, and hit severaltimes with a heavy hammer; but all efforts were futile. 

'_Prognosis_. --Unfavourable. During the latter operations I had a verystrong pressure applied to the hoof, and the horse firmly fastened in everyway, and it appeared as though no amount of force would ever reduce thedislocation. 

'_Tautological_. --The case was destroyed on April 30, being of no furtheruse to the service. 

'_Post-mortem_. --The os coronæ was found to have slipped out of thearticulating cavity of the os pedis, backwards and past the lateralligaments. These last-named structures prevented the bone being forcedforward into its proper position, being firmly locked over the lateralprominences. The capsular ligament was considerably lacerated and inflamed, causing slight effusion and swelling about the region of the coronet. '[A]

[Footnote A: T. Flintoff, A. V. D. , _Veterinary Journal_, vol. Xix. , p. 74. ]

_Treatment_. --After the forcible means of reduction related by Mr. Flintoff, we may add that when they are successful, they should be followedby suitable bandaging of the parts, and rest. The first is effected byapplying plaster of Paris and linen, and the second by having the animalput in slings. 

INDEX

Accidental tearing off of the entire hoofAcute arthritis causes of symptoms of treatment ofAcute laminitis causes of complications in congestion in course of definition of diagnosis in exudation in pathological anatomy of prognosis in suppuration in symptoms of treatment ofAcute periostitis simpleAcute simple coronitis causes of definition of symptoms of prognosis of treatment ofAcute simple synovitisAdvantages of neurectomyAmputational neuroma after neurectomyAnatomy, pathological, of cornApplying poultices, method ofArteries of the footArthritis, acute causes of symptoms of treatment ofArthritis, simple or serousArthritis, suppurative causes of definition of diagnosis of pathology of symptoms of treatment ofArticulation, the first interphalangealArticulation, the second interphalangeal

Bar pad and a half-shoe in the treatment of contracted feetBar shoes in the treatment of contractionBayer's treatment for chronic laminitisBermbach's treatment for cankerBindBone, caries ofBones, fracture of the, after neurectomyBones, fracture of theBones, necrosis ofBones, theBrittle hoof causes of definition of symptoms of treatment ofBroad's treatment of laminitisBroué's expansion shoeBruised sole, chronicButtress foot

Canker Bermbach's treatment of causes of definition of differential diagnosis in history of Hoffmann's treatment of Imminger's treatment of Malcolm's treatment of pathological anatomy of prognosis in Rose's treatment of symptoms of treatment ofCaries of boneCaries of the os pedis in pricked footCartilage, the lateralCartilaginous quittorCauses of acute laminitis of acute simple coronitis of brittle hoof of canker of chronic coronitis of chronic laminitis of club-foot of corn of contracted feet of coronary contraction of the foot of crooked foot of curved hoof of false quarter of flat-foot of keraphyllocele of nail-bound of navicular disease of pumiced foot of punctured foot of ringed hoof of sand-crack of seedy-toe of side-bone of simple chronic coronitis of simple cutaneous quittor of specific coronitis of sub-horny quittor of thrush of weak heelsCaustic solution, Villate'sChanges in the bone in navicular disease in the bursa in navicular disease in the cartilage in navicular disease in the internal structures of the foot in contraction in the tendon in navicular diseaseCharlier shoe, theCharlier shoeing for contracted footChemical properties of hornChronic coronitis, simple causes of definition of symptoms of treatment ofChronic bruised sole treatment ofChronic laminitis Bayer's treatment of causes of definition of Gross's treatment of Gunther's treatment of Imminger's treatment of Joly's treatment of Meyer's treatment of pathological anatomy of surgical shoeing for symptoms of treatment of treatment of, by ligaturing the digital arteriesChronic oedema of the leg after neurectomyChronic synovitisClamp, sand-crack, Koster's McGill's Vachette'sClamping sand-cracks, methods ofClassification of corns of punctured foot according to the situation of the wound of sand-crack of quittorClub-foot causes of definition of symptoms of treatment ofCocaine injections as an aid to diagnosis in foot lamenessesColic, metastatic, in laminitisCommencement, point of, in navicular diseaseCommon situations of the wound in punctured foot. Complicated sand-crack, operations forComplications in coronitis in laminitis in pricked foot in sand-crack in simple or cutaneous quittor in sub-horny quittorCompression as a cause of navicular diseaseConcussion as a cause of navicular diseaseConformation, faultyCongestion in laminitisContracted foot causes of changes in the internal structures of definition of local or coronary prognosis of surgical shoeing for symptoms of treatment ofContraction of the foot, a bar pad and a half-shoe in the treatment of bar shoes in the treatment of expansion shoes in the treatment ofCorn causes of classification of definition of pathological anatomy of prognosis in surgical shoeing in symptoms of the dry the moist the suppurating treatment ofCoronary contraction of the foot causes of definition of symptoms of treatment ofCoronary cushion, theCoronary edge of the wall, expansion and contraction of theCoronitis acute simple causes of complications in definition of prognosis of symptoms of treatment ofCoronitis, simple chronic causes of definition of symptoms of treatment ofCoronitis, specific causes of definition of symptoms of treatment ofCourse of acute laminitisCrooked foot causes of definition of symptoms of treatment ofCurved hoof causes of definition of treatment ofCushion the coronary the plantarCutaneous or simple quittor

De Fay's expansion shoe. Defective or irregular blood-supply to the bone a cause of navicular diseaseDefinition of acute laminitis of acute simple coronitis of brittle hoof of canker of chronic coronitis of chronic laminitis of club-foot of contracted foot of corn of coronary contraction of the foot of crooked foot of curved hoof of false quarter of flat-foot of keraphyllocele of nail-bound of navicular disease of pumiced foot of punctured foot of pyramidal disease of quittor of ringed hoof of sand-crack of seedy-toe of side-bone of simple chronic coronitis of specific coronitis of spongy hoof of sub-horny quittor of thrush of weak heelsDevelopment of the hoofDiagnosis of acute laminitis of canker of foot lameness by injections of cocaine of navicular disease of punctured foot of pyramidal disease of side-bone of sub-horny quittorDifferential diagnosis in canker in navicular diseaseDiseases arising from faulty conformationDislocation of the os coronæ recorded case ofDislocationsDry corn

Einsiedel's expansion shoeExamining the foot method ofExercise, forced, in the treatment of laminitisExpansion and contraction of the coronary edge of the wall of the hoof under the body-weight of the solar edge of the wall of the soleExpansion shoe Broué's De Fay's Einsiedel's Hartmann's Smith'sExpansion shoes in the treatment of contractionExtensor pedis tendon, theExtirpation of the lateral cartilage in quittor of the lateral cartilage, after Moller and Frick of the lateral cartilage, after BayerExudation in laminitis

False quarter causes of definition of symptoms of treatment ofFaulty conformation diseases arising fromFeeding a cause of laminitisFlat-foot causes of definition of symptoms of treatment ofFlexor pedis perforans tendon, theFlexor pedis perforatus tendon, theFoot, buttressFoot, changes in the internal structures in contraction of theFoot, contracted causes of definition of prognosis of symptoms of treatment ofForced exercise in laminitisFracturesFractures of the bones after neurectomy of the navicular bone of the os coronæ of the os pedisFrog, theFunctions of the lateral cartilages

Gangrene of the sensitive structures in laminitisGathered nailGelatinous degeneration after neurectomyGrooving the wall in laminitis (Smith's operation) in treatment of sand-crack in treatment of side-bone (Smith's operation)Gross's treatment of chronic laminitisGrowth of hoof, rate ofGunther's treatment of chronic laminitis

Hartmann's expansion shoeHeels, weak causes of definition of symptoms of treatment ofHeredity as a cause of navicular disease as a cause of side-boneHistology of hornHistory of canker of navicular disease of neurectomyHind-feet, navicular disease in theHind-limb with the side-line, method of securingHoffmann's treatment of cankerHoof, the accidental tearing off of expansion and contraction of development of rate of growth ofHorn chemical properties of histology ofHutlederkitt

Imminger's treatment for chronic laminitis for cankerImmobilizing a sand-crack by grooving the wall, methods ofInfection of the limb, septicInjections of cocaine as an aid to diagnosis in foot lamenessInterphalangeal articulation the first the secondInstruments required in plantar neurectomy in operations on the footIrregular blood-supply to the bone as a cause of navicular disease

Joly's treatment of chronic laminitis

Koster's sand-crack clampKeraphyllocele causes of definition of pathological anatomy of symptoms of treatment ofKeratoma

Lameness, cocaine injections as an aid to diagnosis inLaminæ, the sensitiveLaminitis acute Broad's treatment of causes of complications in congestion in course of definition of diagnosis in exudation in feeding, a cause of forced exercise in the treatment of gangrene of the sensitive structures in grooving the wall in the treatment of local applications in the treatment of local bleeding in the treatment of metastatic colic in metastatic pneumonia in neurectomy in opening the sole in the treatment of parturient pathological anatomy of periostitis and ostitis in phlebotomy in the treatment of prognosis in rocker bar shoes in the treatment of Smith's operation in suppuration in symptoms of symptoms of, in the four feet symptoms of, in the fore-feet alone symptoms of, in the hind-feet alone treatment ofLaminitis chronic Bayer's treatment of causes of definition of Gross's treatment of Gunther's treatment of Imminger's treatment of Joly's treatment of Meyer's treatment of pathological anatomy of surgical shoeing for symptoms of treatment ofLaminitis, parturientLateral cartilage, the extirpation of, in quittor, after Holier and Frick extirpation of, in quittor, after Bayer functions of necrosed, pathological anatomy of necrosis of ossification of wounds ofLeg, chronic oedema of the, after neurectomyLength of rest required after neurectomyLigaments, theLigaturing the digital arteries, in chronic laminitisLimb, septic infection ofLocal applications in laminitisLocal bleeding in laminitisLocal or coronary contraction of the footLow ringbone

Malcolm's treatment of cankerMcGill's sand-crack clampMedian neurectomyMetal plates in the treatment of sand-crackMetastatic colic in laminitisMetastatic pneumonia in laminitisMethods of applying poultices of examining the foot of immobilizing sand-crack by grooving the wallMethods of restraint of securing a hind-limb with the side-line of securing the foot to the cannon of another limbMeyer's treatment of chronic laminitisMoist corn

Nail-bound causes of definition of symptoms of treatment ofNail-treadNavicular bone, the fracture ofNavicular bursa, puncture of the, in pricked footNavicular bursa punctured, treatment ofNavicular disease causes of changes in the bone in changes in the bursa in changes in the cartilage in changes in the tendon in definition of diagnosis of differential diagnosis of history of in the hind-feet point of commencement of prognosis of symptoms of treatment ofNecrosed lateral cartilage pathological anatomy ofNecrosis of bone of tendon and ligament in sub-horny quittor of the lateral cartilage (cartilaginous quittor)Necrotic plantar aponeurosis, treatment ofNerve, reunion of, after neurectomyNerves, theNeurectomy advantages of amputational neuroma in fracture of the bones after gelatinous degeneration after history of instruments required in in laminitis length of rest required after persistent pruritus after pricked foot after reunion of divided nerve after sequelæ of stumbling after use of the horse afterNeurectomy median plantarNeuroma, amputational, after neurectomy

Oedema of the leg after neurectomyOpening the sole in the treatment of laminitisOperation for complicated sand-crack for laminitis for necrosed lateral cartilage in quittor for necrosed plantar aponeurosis for side-boneOperations on the foot, instruments required inOperations on the horn, treatment of contracted foot byOs coronæ, the dislocation of fracture ofOs pedis, the caries of, in pricked foot fracture ofOsteoplastic ostitisOsteoplastic periostitisOstitis in laminitisOstitis, rarefying osteoplasticOssification of the lateral cartilages (side-bone)Overreach shoeing for treatment of

Parturient laminitisPathological anatomy of acute laminitis of canker of chronic laminitis of corn of keraphyllocele of necrosed lateral cartilage of pyramidal disease of simple cutaneous quittor of navicular diseasePedal articulation, puncture of thePerforans tendon, the flexor pedisPerforates tendon, the flexor pedisPeriople, thePeriostitis and ostitis in laminitisPeriostitis, osteoplasticPeriostitis, recorded cases ofPeriostitis, simple acute suppurativePeriostitis, treatment ofPersistent pruritus after neurectomyPhlebotomy in laminitisPlantar aponeurosis, wounds of the treatment of necrosedPlantar cushionPlantar neurectomy history of instruments required in operation ofPneumonia in laminitis metastaticPoint of commencement of navicular diseasePoultices, methods of applyingPreventive treatment of cutaneous quittorPricked foot after neurectomy complications ofPrognosis in acute simple coronitis in canker in contracted foot in corn in laminitis in navicular disease in punctured foot in sand-crack in simple cutaneous quittorProperties of horn, chemicalProtection of sand-crack by metal platesPruritus after neurectomyPumiced foot causes of definition of symptoms of treatment ofPunctured foot causes of classification of common situation of the wound in complications in definition of diagnosis of prognosis of symptoms of treatment ofPuncture of the navicular bursa treatment ofPuncture of the pedal articulationPurulent synovitisPyramidal disease

Quittor classification of definition ofQuittor, simple or cutaneous causes of complications in curative treatment of definition of pathological anatomy of preventive treatment of prognosis of symptoms of treatment of sub-horny causes of complications in definition of diagnosis of extirpation of the lateral cartilage in, after Moller and Frick extirpation of the lateral cartilage in, after Bayer necrosis of the lateral cartilage in (cartilaginous quittor) necrosis _of_ tendon and ligament in (tendinous quittor) surgical shoeing in symptoms of treatment of

Rarefying ostitisRecorded case of dislocation of the os coronæ of navicular disease in both hind-feet of periostitis of pyramidal diseaseRest required after neurectomy, length ofRestraint, methods ofReunion of the divided nerve after neurectomyRingbone, lowRinged hoof causes of definition of treatment ofRocker bar shoes in laminitisRose's treatment of canker

Sand-crack causes of clamp Koster's McGill's Vachette's clamping, methods of classification of complications in definition of operations for complicated prognosis in surgical shoeing for symptoms of treatment of treatment of, by grooving the wall treatment of, by wedging the fissureSecond interphalangeal articulation, theSecuring a hind-limb with the side-line, method ofSecuring the foot to the cannon of another limb, method ofSeedy-toe causes of definition of symptoms of treatment ofSenile decay as a cause of navicular diseaseSensitive laminæ, theSensitive structures, gangrene of, in laminitisSeptic infection of the limbSequelæ of neurectomySerous arthritisShoe, bar Charlier's Charlier's tip expansion Broué's De Fay's Einsiedel's Hartmann's Smith's for overreach plate rocker bar slipper, Broué's slipper and bar-clip, Einsiedel's three-quarter three-quarter bar thinned tip tip with 'dropped' heel with extended toe-piece with extended toe-piece (Nunn's) with heel-clip with 'set' heelSide-bone causes of definition of diagnosis of heredity a cause of Smith's operation for symptoms of treatment ofSide-line, theSimple acute coronitisSimple acute periostitisSimple coronitis acute chronicSimple or cutaneous quittor causes of complications in curative treatment of definition of pathological anatomy of preventive treatment of prognosis of symptoms of treatment ofSimple serous arthritisSimple synovitis, acuteSmith's expansion shoe operation for laminitis operation for side-boneSolar edge of the wall, expansion and contraction of theSole, chronic bruisedSole, expansion and contraction of theSole, theSpecific coronitis causes of definition of symptoms of treatment ofSpongy hoof definition of symptoms of treatment ofStumbling after neurectomySub-horny quittor causes of complications in definition of diagnosis of necrosis of the lateral cartilage in (cartilaginous quittor) necrosis of tendon and ligament in (tendinous quittor) symptoms of treatment of surgical shoeing forSuppurating cornSuppuration in laminitisSuppurative arthritis causes of definition of diagnosis of pathology of symptoms of treatment ofSuppurative periostitisSuppurative synovitisSurgical shoeing for corn for chronic laminitis for laminitis, acute for sand-crack for quittorSymptoms of acute simple coronitis of brittle hoof of canker of chronic coronitis of chronic laminitis of club-foot of contracted foot of corn of coronary contraction of the foot of crooked foot of false quarter of flat-foot of keraphyllocele of laminitis of laminitis in all four feet of laminitis in the fore-feet alone of laminitis in the hind-feet alone of nail-bound of navicular disease of pumiced foot of punctured foot of pyramidal disease of sand-crack of seedy-toe of side-bone of simple chronic coronitis of simple cutaneous quittor of specific coronitis of spongy hoof of sub-horny quittor of synovitis, chronic of synovitis, purulent or suppurative of synovitis, simple acute of thrush of weak heelsSynovitis, acute simple causes of treatment of

Tearing off of the entire hoof, accidentalTendon the extensor pedis the flexor pedis perforans the flexor pedis perforatusTendons, theThrush causes of definition of symptoms of treatment ofTight-nailingTip-shoesTissue, the velvetyTread, See OverreachTreatment of acute laminitis of acute simple coronitis of brittle hoof of canker of canker Bermbach's Hoffmann's Imminger's Malcolm's Rose's of chronic bruised sole of chronic coronitis of chronic laminitis of chronic laminitis by ligaturing the digital arteries of club-foot of contracted feet of contracted feet by expansion shoes of contracted feet by operations on the horn of corns of coronary contraction of the foot of crooked foot of curved hoof of cutaneous quittor of false quarter of keraphyllocele of nail-bound of navicular disease of necrotic plantar aponeurosis of periostitis of pumiced foot of punctured foot of punctured navicular bursa of pyramidal disease of ringed hoof of sand-crack of sand-crack by clamping the fissure of sand-crack by grooving the wall of sand-crack by wedging the fissure of seedy-toe of side-bone of simple chronic coronitis of specific coronitis of spongy hoof of sub-horny quittor of synovitis of thrush of weak heelsUse of the horse that has undergone neurectomyVachette's sand-crack clampVeins, theVelvety tissue, theVillate's caustic solution

Wall, theWeak heels causes of definition of symptoms of treatment ofWedging the fissure in the treatment of sand-crackWound in punctured foot, common situations of theWounds of the lateral cartilagesWounds of the plantar aponeurosis

THE END