Chapter XXI: Part 21

The external appearance ought to be sufficient to determine the diagnosis, but there are a few signs which may contribute toward a nicer identification of the lesion. The capped hock, whether under the appearance of an acute, edematous swelling, or as a bloody serous collection, or as a simple serous cyst, does not give rise to any remarkable local manifestation other than such as have already passed under our survey in considering similar cases, nor will it be liable to interfere with the functions which belong to the member in question, unless it assumes very large dimensions and on each side of the tendons, as well as on the summit of the bone. But if the inflammation is quite high, if suppuration is developing, if there is a true abscess, or--and this is a common complication--especially when the kicking or rubbing of the animal is frequently recurring, then, besides the local trouble of the cyst or of the abscess, the bones become diseased and the periosteum inflamed; perhaps the superior ends of the bone and its fibro-cartilage become affected, and a simple lesion or bruise, whatever it may have been, becomes complicated with periostitis and ostitis, and is naturally accompanied with lameness, developed in a greater or less degree, which in some cases may be permanent and in others increased by work. These complications, however, are not common or frequent.

_Treatment._--Capped hocks are in many cases amenable to treatment, and yet they often become the opprobrium of the practioner by remaining, as they frequently do, an eyesore on the top of the hock; they do not interfere, it is true, with the work of the horse, but fixing upon him the stigma of what, in human estimation, is a most unreliable and objectionable reputation, to wit, that of being an habitual "kicker," and, worse than all, one that kicks when fed.

The maxim that "an ounce of prevention is worth a pound of cure" fits the present case very neatly. A horse whose hocks have a somewhat puffy look and whose skin on the front of the hock is loose and flabby, justly subjects himself to a suspicion of addictedness to this bad habit, but a little watching will soon establish the truth. If, then, the verdict is one of conviction, precautions should be immediately adopted against a continuance of the evil. The padding of the sides of the stall with straw mats or mattresses and covering the posts with similar material, in such manner as to expose no hard surface with which to come in contact, will reduce the evil to its minimum. The animal may jar his frame when he kicks, but even then there will be less force in the concussion than if it impinged upon the solid plank, and cuts and abrasions can not be inflicted by a properly made cushion. Hobbles are also rightly recommended with a view to the required restraint of motion, so applied as to secure the leg with which the kicking is performed, or even both hind legs, in such manner as not to interfere with the movement of lying down and rising again and yet preventing that of kicking backward. Boots similar in pattern to those which are used for the prevention of shoe boil are also prescribed. These are placed above the hock and retained by straps tightly fastened. We apprehend, however, that the difficulty of retaining them in the proper place without the danger of chafing from the tightness of the straps may form an objection to their use. Notwithstanding all precautions, hocks will be capped in the future as in the past, and the study of their treatment will always be in order.

The mode of dealing with them will, of course, be greatly influenced by the condition of the parts. When the inflammation is excessive and the swelling large, hot, and painful to the touch, the application of warm water will be very painful. The leg should be well fomented several times a day, for from 15 to 20 minutes each time, a strong decoction of marsh-mallow leaves being added to the water, and after each application swathed with flannel bandages soaked in the same warm mixture. A few days of this treatment will usually effect a resolution of the inflammation; if not complete, at least sufficiently so to disclose the correct outlines of the hygroma and exhibit its peculiar and specific symptoms. The expediency of its removal and the method of accomplishing it are then to be considered, with the question of opening it to give exit to its contents. If the fluid is of a purulent character, the indication is in favor of its immediate discharge. No time should be lost, and it should be by means of a small opening made with a narrow bistoury. If, however, the fluid is a serosity, we prefer to remove it by punctures with a very small trocar. Our reason for special caution in these cases is our fear of the possibility of the existence of diseased conditions of a severe character in the pseudo joint. For the same reason we prefer the treatment of those growths by external applications. In the first stages of the disease a severe and stiff blister, such as the cantharidate of collodium, entirely covering the cyst, perhaps not yet completely formed, when the inflammation has subsided, will be of great benefit by its stimulating effect, the absorption it may excite, and the pressure which, when dry, it will maintain upon the tumor. If, however, the thickening of the growth fails to diminish, it should be treated with some of the iodin preparations in the form of ointments, pure or in combination with potassium, mercury, etc., of various strengths and in various proportions. My opinion of setons is not favorable, but the actual cautery, by deep and fine firing, in points--needle cauterization--I believe to be the best mode of treatment, and especially when applied early.

A very satisfactory way to treat these cases is to burst the swelling by pressure from without. A strap or strong linen bandage is placed about the hock, pressing on the bursa, while the affected leg is on the ground, the other hind foot being lifted up. When the bandage is in place the leg should be released, and the horse will violently flex the bandaged limb and produce pressure on the bursa, with consequent bursting and discharging of its contents.

Whatever treatment may be adopted for capped hock, patience must be one of the ingredients. In these parts absorption is slow, the skin is very thick, and its return to a soft, pliable, natural condition, if effected at all, will take place only after weeks added to other weeks of medical treatment and patient waiting.

INTERFERING, AND SPEEDY CUTS.

These designations belong to certain special injuries of the extremities, produced by similar causes, giving rise to kindred pathological lesions with allied phenomena, requiring about the same treatment and often followed by the same results, to wit, a blemish which may not only subject the animal to a suspicion of unsoundness, but in some special circumstances may interfere with his ability to labor. It is known as "interfering" when the location of the trouble is the inside of the fetlock of either the fore or hind leg. It is called "speedy cut" when it occurs on the inside of the fore leg, a little below the knee, at the point of contact of that joint with the cannon. It is always the result of a blow, self-inflicted, of varying severity, and giving rise to various lesions. (See also p. 399.)

_Symptoms._--At times the injury is too slight to be seriously noticed, the hair being scarcely cut and the skin unmarked. At other times the skin will be cut through, partly or wholly, and it may for the time cause sufficient pain to check the motion of the animal and induce him to suspend his labor through his inability to use the wounded limb, traveling meanwhile for a short space on three legs only. Sometimes a single blow will suffice, or again there will be a repetition of lighter strokes. In the latter case the parts will become much swollen, hot, and so painful to the touch that the motion of the knee or the fetlock will be sufficiently disturbed to cause lameness of a degree of severity corresponding to that of the lesion. Following the subsidence of this diffused and edematous swelling is sometimes the formation of a tumor, either at the knee or the fetlock. This may be soft at first or become so by degrees, with fluctuation, its contents being at first extravasated blood, and later a serosity; or, if there has been a sufficient degree of inflammation, it may become suppurative. The result of the fault of interfering may thus be exhibited, whether at the knee or at the fetlock, as characterized by all the pathological conditions which have appeared as accompaniments of capped knee or capped hock. If, in consequence of the force of the blow or blows, the inflammation has been usually severe, a mortification of the skin may become one of the consequences, a slough taking-place, succeeded by a cutaneous ulcer on the inside of the fetlock or when the greater number of the original wounds are inflicted. If the interfering has been often repeated it may be followed by another condition, which has been considered in our remarks upon other affections. It is a plastic exudation or thickening of the parts, which are commonly said to have become "callous," and the effect of it is to destroy the regularity of the outlines of the joint to an extent which constitutes a serious blemish, which will be permanent, and according to the degree of the aberration from the natural and symmetrical lines will inevitably depreciate the commercial value of the animal.

An animal in interfering may thus exhibit a range of symptoms which from the simplest form of a mere "touching," may successively assume the serious characters of an ugly cicatrix, a hard, plastic swelling, or perhaps, as witnessed at the knee, of periostitis with its sequelae.

If a single and constantly recurring cause--a blow--is the starting point in interfering, we may now consider the subject of the predisposition which brings such serious results upon the suffering animal, and the conditions which lead to and accompany it. These are numerous, but the first in frequency and importance is peculiarity of conformation in the animals addicted to it. The first class will include horses, whose chests are narrow and whose legs do not stand straight and upright, but are crooked and pigeon-toed in and out. The second class includes those whose legs are weak, either from youth or hard labor, or from severe attacks of sickness. Another class is made up of those having abnormally developed feet, or which have been badly shod with unnecessarily wide or heavy shoes. Another class consists of those that are affected with swollen fetlocks or chronic, edematous swelling of the leg. Another is formed of animals with a peculiar action, as those whose knee action is very high, and it is these that furnish most of the cases of speedy cut.

_Prognosis._--The prognosis of interfering is never a very serious one. However violent the blow may be it is rarely that subsequent complications of a troublesome nature occur. The principal evil attending it is a liability to be followed by a thickened or callous deposit which is not only an eyesore and a blemish, but constitutes a new and increased predisposition. The remark that "an animal which has interfered once is always liable to interfere," is often confirmed and sanctioned by a recurrence of the trouble.

_Treatment._--Another point in which there is a resemblance between this lesion and others which we have considered is in its responsiveness to the same treatment with them. Indeed, the prescription of warm fomentations, soothing applications, and astringent and resolvent mixtures, in a majority of cases, is the first that occurs all through the list. If the swelling assumes the character of a serous collection, pressure, cold water, and bandages will contribute to its removal. If suppuration seems to be established and the swelling assumes the character of a developing abscess, hot poultices of flaxseed or of boiled vegetables and the embrocations of sedative ointments, those of basilicon, or vaseline, impregnated with preparations of opium or belladonna--all these recommend themselves by their general adaptation and the beneficial results which have followed their administration, not less in one case than in another. When an abscess has formed and is fluctuating, it should be carefully but fully opened to evacuate the pus. If it is a serous cyst, some care is necessary in emptying it, and the possibility of the extension of the inflammation to the joint must be taken into consideration. When the cavities have been emptied and have closed by filling up with granulations, or if, not being opened, the contents have been reabsorbed, and there remains in either case a plastic exudation and a tendency to the callous organization that may yet exist, blisters under their various forms, including those of cantharides, of mercury, and of iodin, are then indicated, principally in the early stages, as it is then that their effects will prove most satisfactory. The use of the actual cautery, with fine points, penetrating deeply throughout the enlargement, has in our hands, when used in the very early stages of its formation, nearly always brought on a radical recovery with complete absorption of the thickening.

STRINGHALT.

This is an involuntary movement of one or both hind legs, in which the foot is suddenly and spasmodically lifted from the ground much higher than it is normally carried, with excessive flexion of one bone upon the other. This peculiarity is usually prominent, although it may disappear with work, only to reappear after a short rest. Sometimes it is most apparent at a trot, sometimes at a walk, and other times only when turned around; or it may not be affected by the gait of the horse. It does not seem to be influenced by the horse's age, young and old being alike affected. Its first manifestations are sometimes very slight. It has been noticed as occurring in an animal when backing out of his stable and ceasing immediately after. In some animals it is best seen when the animal is turning around on the affected leg, and it is not noticed when he moves straight forward. That this peculiar action interferes with facility of locomotion and detracts from a horse's claim to soundness can not for a moment be denied.

_Cause._--Veterinarians and pathologists are yet in doubt in respect to the cause of this affection, as well as to its essential nature. Whether it results from disease of the hock, of an ulcerative character; whether it springs from a malformation; whether it is a shortening of the ligaments, a chronic inflammation of the sciatic nerve, or a disease of the spinal cord; whether it is purely a muscular or purely a nervous lesion, or a compound of both--it still continues, if an etiologist is bound to possess universal knowledge within the scope of his special studies, to be his reproach and his puzzle.

_Treatment._--When there is a known or suspected cause the treatment should be directed toward this factor. If due to local inflammation of the hock or foot, only this local lesion should be treated. If it remains after the local lesion has healed, or if we have no assignable cause, the best results have followed the sectioning of the lateral extensor of the foot. A competent veterinarian alone should undertake this operation.

THROMBOSIS.

There are certain forms of lameness which are very peculiar in their manifestation, and which to the nonprofessional mind must appear to belong to the domain of mystery or theory instead of occupying a well-established position among the subjects of equine pathology. Yet they are no less susceptible of actual demonstration and of positive comprehension than many facts which, plain and familiar to the general understanding now, were once ranked among things occult and unsearchable. A thrombus, considered as a cause of lameness, may find a place among these understood mysteries.

_Cause._--Under certain peculiar conditions of inflammation of the blood vessels, and also in aneurisms, clots of blood are sometimes formed in the arteries and find their way in the general circulation. At first, while very small, or sufficiently so to pass from one vessel to another, they move from a small vessel to a larger, and from that to one still larger, constantly increasing in size until at some given point, from their inability to enter smaller vessels, their movement is finally arrested. The artery is thus effectually dammed, and the clot in a short time cuts off completely the supply of blood from the parts beyond. This is thrombosis, and it often gives rise to sudden and excessive lameness of a very painful character.

_Symptoms._--Thrombi may form in any of the arteries, and doubtless have been the cause of many cases of lameness which could never be accounted for. If they exist in small arteries their diagnosis will probably fail to be made out with certainty, but when situated in the larger trunks a strong suspicion of their presence may be excited. In some cases they may even be recognized with positive accuracy, as when the vessels which supply the posterior extremities are affected by the blocking up of the posterior aorta or its ramifications.

The existence of thrombosis of the arteries of the hind leg may always be suspected when the following history is known: The general health of the animal is good, but symptoms of lameness in one of the legs have been developed, becoming more marked as he is worked, and especially when driven at a fast gait. But the disturbance is not permanent, and the lameness disappears almost immediately after a rest. There is an increase of the difficulty, however, and, though the animal may walk normally, he will, when made to trot, very soon begin to slacken his pace and to show signs of the trouble, and if urged to increase his speed will become lamer and lamer; an abundant perspiration will break out; he will refuse to go, and if forced he shows weakness behind, seems ready to fall, and perhaps does fall. While on his feet the leg is kept in constant motion, up and down, and is kept from the ground as if the contact were too painful to bear. If undisturbed this series of symptoms will gradually subside, sometimes very soon, and occasionally after a few hours he will return to an apparently perfect condition. A return to labor will lead to a renewal of the same incidents.

A history like this suggests a strong suspicion of a thrombus in an artery of the hind leg, and this suspicion will be confirmed by the external symptoms exhibited by the animal. The total absence of any other disease which might account for the lameness, and a manifest diminution of heat over a part or the whole of the extremity, when compared with the opposite side or with any other portion of the body; a sensation of cold attendant on the pain, but gradually subsiding as the pain subsides, and the circulation, quickened by the rest, has been reestablished throughout the extremity; all these are confirmatory circumstances. Still, it is thus far only a suspicion, and absolute certainty is yet wanting. To establish the truth of the case the rectal exploration must be resorted to. The hands then, well prepared and carefully introduced into the rectum, must explore for the truth, first feeling for the large blood vessels which, divided at the aorta, separate to supply the right and left legs. These must be compared in respect to the pulsation and other particulars. The artery which is healthy will, of course, exhibit all the proper conditions of that state. On the other hand, if the vessel appears to the feel hard, more or less cordy, and pulseless, or giving a sensation of fluttering, as of a small volume of blood with a trickling motion passing through a confined space, the difference between the sides will make the case plain. The first will be the full flow of the circulation through an unobstructed channel, the other a forced passage of the fluid between the thrombus and the coats of the artery. In such case the prognosis is necessarily a grave one and the disease is more liable to grow Worse than better.

_Treatment._--No form of treatment can be advised; the suffering or a helpless and useless animal can only be terminated by that which ends all.

Cases occur, however, where this condition of the blood vessels exists in a much less degree, and the diseased condition is not sufficiently pronounced for final condemnation. There may even be a possibility of the absorption of the clot, or that an increase of the collateral circulation may be sufficient to supply the parts with blood. In such cases spontaneous recovery may follow moderate exercise in the pasture, field, or stable, or continuous light work may be given, but too much hope should not be placed in such treatment.

SPRAINS OF THE LOINS.

This is an affection which suggests to the mind the idea of muscular injury, and is difficult to distinguish from many similar cases. If the animal shrinks from the slightest pressure or pinching of the spine in the region of the loins, he is by many pronounced to be "lame in the loins," or "sprained in the loins," or "weak in the kidneys." This is a grave error, as in fact this simple and gentle yielding to such a pressure is not a pathological sign, but is normal and significant of health. Yet there are several conditions to which the definition of "sprains of the loins" may apply which are not strictly normal.

_Cause._--The muscles of the back and those of the loins proper, as the psoas, may have been injured, or again there may be trouble of a rheumatic nature, perhaps suggestive of lumbago. Diseases of the bones of the vertebral column, or even those of the organs of circulation, may give rise to an exhibition of similar symptoms.

_Symptoms._--The symptoms are characteristic of a loss of rigidity or firmness of the vertebral column, both when the animal is at rest and in action. In the former condition, or when at rest, there is an arched condition of the back and a constrained posture in standing, with the hind legs separated. In the latter there is a lateral, balancing movement at the loins, principally noticeable while the animal is in the act of trotting--a peculiar motion, sometimes referred to as a "crick in the back," or what the French call a "tour de bateau." If, while in action, the animal is suddenly made to halt, the act is accompanied with much pain, the back suddenly arching or bending laterally, and perhaps the hind legs thrown under the body, as if unable to perform their functions in stopping, and sometimes it is only accomplished at the cost of a sudden and severe fall. This manifestation is also exhibited when the animal is called upon to back, when a repetition of the same symptoms will also occur.

If a slight pressure on the back or the loins is followed by a moderate yielding of the animal, it is, as before remarked, a good sign of health. With a sprain of the loins pressure of any kind is painful, and will cause the animal to bend or to crouch under it more or less, according to the weight of the pressure. Heavy loads, and even heavy harnessing, will develop this tenderness. In lying down he seems to suffer much discomfort, and often accompanies the act with groaning, and when compelled to rise does so only with great difficulty and seldom succeeds without repeated efforts.

Sprains of muscles proper, when recent, will always be accompanied with this series of symptoms, and the fact of their exhibition, with an excessive sensibility of the parts, and possibly with a degree of swelling, will always justify a diagnosis of acute muscular lesion, and especially so if accompanied with a history of violent efforts, powerful muscular strains, falls, heavy loading, etc., connected with the case. If the symptoms have been of slow development and gradual increase, it becomes a more difficult task to determine whether the diagnosis points to pathological changes in the structure of the muscles or of the bones, the nervous centers, or the blood vessels of the region. And yet it is important to decide as to which particular structure is affected in reference to the question of prognosis, as the degree of gravity of the lesion will depend largely upon whether the disabled condition of the animal is due to an acute or a chronic disease.

_Treatment._--The prescription which will necessarily first of all suggest itself for sprains of the loins is rest. An animal so affected should be immediately placed in slings, and none of his efforts to release himself should be allowed to succeed. Hot compresses, cold-water douches, sweating applications, stimulating frictions, strengthening charges, blistering ointments of cantharides and the actual cautery, all have their advocates, but in no case can the immobility obtained by the slings be dispensed with. In many cases in which the weakness of the hind quarters was caused by disease of the nervous centers electricity has also yielded good results.

FOOTNOTES:

[2] This bandage consists of a cloth drenched in warm water or a dripping bandage laid around the diseased part, then covered by several layers of woolen blanket or cloth, which is in turn covered by parchment paper, rubber cloth, or other impervious material. Heat, moisture, and pressure are obtained by such a bandage if water is poured upon it several times daily.

DISEASES OF THE FETLOCK, ANKLE, AND FOOT.

By A. A. HOLCOMBE, D. V. S.,

_Veterinary Inspector, Bureau of Animal Industry._

ANATOMICAL REVIEW OF THE FOOT.

In a description of the foot of the horse it is customary to include only the hoof and its contents, yet, from a zoological standpoint, the foot includes all the leg from the knee and the hock down.

The foot of the horse is undoubtedly the most important part of the animal, so far as veterinary surgery is concerned, for the reason that it is subject to so many injuries and diseases which in part or in whole render the patient unfit for the labor demanded of him. The old aphorism "no foot no horse" is as true to-day as when first expressed; in fact, domestication, coupled with the multiplied uses to which the animal is put, and the constant reproduction of hereditary defects and tendencies, has largely transformed the ancient "companion of the wind" into a very common piece of machinery which is often out of repair, and at best is but shortlived in its usefulness.

Since the value of the horse depends largely or even entirely upon his ability to labor, it is essential that his organs of locomotion be kept sound. To accomplish this end it is necessary not only to know how to cure all diseases to which these organs are liable but, better still, how to prevent them.

An important prerequisite to the detection and cure of disease is a knowledge of the construction and function of the parts which may be involved in the diseased process. Hence, first of all, the anatomical structures must be understood. (See also p. 583.)

The bones of the fetlock and foot constitute the skeleton on which the other structures are built and comprise the lower end of the cannon bone (the metacarpus in the fore leg, the metatarsus in the hind leg), the two sesamoids, the large pastern or os suffraginis, the small pastern or coronet, the small sesamoid or navicular bone, and the coffin bone or os pedis. (Plate XXXIV, fig. 3.)

The cannon bone extends from the knee or hock to the fetlock, is cylindrical in shape, and stands nearly or quite perpendicular.

The sesamoids occur in pairs, are small, shaped like a three-faced pyramid, and are set behind the fetlock joint, at the upper end of the large pastern, with the base of the pyramid down.

The large pastern is a very compact bone, set in an oblique direction downward and forward, and extends from the cannon bone to the coronet.

The coronet is a short, cube-shaped bone, set between the large pastern and coffin bone, in the same oblique direction.

The navicular bone is short, flattened above and below, and is attached to the coffin bone behind.

The coffin bone forms the end of the foot and is shaped like the horny box in which it is inclosed.

All these bones are covered on the surfaces which go to make up the joints with a cartilage of incrustation, while the portions between are covered with a fibrous membrane called the periosteum.

The joints of the legs are of especial importance, since any interference with their function very largely impairs the value of the animal for most purposes. As the joints of the foot and ankle are at the point of greatest concussion they are the ones most subject to injury and disease.

There are three of these joints--the fetlock, pastern, and coffin. They are made by the union of two or more bones, held together by ligaments of fibrous tissue, and are lubricated by a thick, viscid fluid, called synovia, which is secreted by a special membrane inclosing the joints.

The fetlock joint is made by the union of the lower end of the cannon and the upper end of the large pastern bones, supplemented by the two sesamoids, so placed behind the upper end of the pastern that the joint is capable of a very extensive motion. These bones are held together by ligaments, only one of which--the suspensory--demands special mention.

The suspensory ligament of the fetlock starts from the knee, extends down behind the cannon, lying behind the two splint bones, until near the fetlock, where it divides and sends a branch on each side of the joint, downward and forward, to become attached on the sides of the extensor tendon at the lower end of the pastern bone. As it crosses the sesamoids, on the posterior borders of the fetlock, it throws out fibers which hold it fast to these bones. (Plate XXXIV, fig. 2.)

The pastern joint is made by the union of the two pastern bones.

The coffin joint is made by the union of the small pastern, coffin, and small sesamoid, or navicular bones, the latter being set behind and beneath the joint surface of the coffin bone in such way as to receive largely the weight of the small pastern.

Three tendons serve to move the bones of the foot one on another. Two of these flex, or bend, the joints, while the other extends, or straightens, the column of bones. (Plate XXXIII, fig. 5.)

The flexor pedis perforans, or deep flexor of the foot, passes down behind the cannon bone, lying against the suspensory ligament in front, crosses the fetlock joint in the groove made by the union of the two sesamoids, and is attached to the bottom on the coffin bone, after covering the navicular, by a wide expansion of its fibers. It is the function of this tendon to flex the coffin bone and, with it, the horny box.

The flexor pedis perforatus, or superficial flexor of the foot, follows the course of the preceding tendon and is attached to the middle of the ankle. The function of this tendon is to flex the foot at the fetlock.

The extensor pedis runs down in front of the leg, is attached on the most prominent point of the coffin bone, and has for function the straightening of the bones of the ankle and foot.

The bones, ligaments, and tendons are covered by a loose connective tissue, which gives a symmetry to the parts by filling up and rounding off, and all are protected by the skin and hoof.

The skin of the fetlock and ankle is generally characterized by its thickness and the length of its hairs, especially around the hind parts of the fetlock joint in certain breeds of horses. The most important part of this envelope is that known as the coronary band.

The coronary band is that portion of the skin which secretes the horn of which the wall of the hoof is made. This horn much resembles the nail which grows on the fingers and toes of man. It is composed of cylindrical tubes, which are held together by a tenacious, opaque matter. The horn extends from the coronary band to the lower border of the hoof. (Plate XXXII, fig. 1.)

The hoof is a box of horn, consisting of a wall, sole, and frog, and contains, besides the coffin, navicular, and part of the small pastern bones, the sensitive laminae, plantar cushion, and the lateral cartilages. (Plate XXXIII, fig. 4.)

The sole of the foot incloses the box on the ground surface, is shaped like the circumference of the foot, except that a V-shaped opening is left behind for the reception of the frog, and is concave on the lower surface. The sole is produced by the velvety tissue, a thin membrane covering the plantar cushion and other soft tissues beneath the coffin bone. The horn of the sole differs from the horn of the wall in that its tubes are not straight and from the fact that it scales off in pieces over the whole surface.

The frog is a triangular-shaped body, divided into two equal parts by a deep fissure, extending from its apex in front to the base. It fills the triangular space in the sole, to which it is intimately attached by its borders. The horn of the frog is produced in the same manner as the sole; but it differs from both the wall and sole in that the horn is soft, moist, and elastic to a remarkable degree. It is the function of the frog to destroy shock and to prevent slipping.

The sensitive laminae are thin plates of soft tissue covering the entire anterior surface of the coffin bone. They are present in great numbers, and by fitting into corresponding grooves on the inner surface of the horn of the wall the union of the soft and horny tissues is made complete. (Plate XXXII, fig. 1.)

The plantar cushion is a thick pad of fibrous tissue placed behind and under the navicular and coffin bones and resting on the sole and frog, for the purpose of receiving the downward pressure of the column of bones and to destroy shock. (Plate XXXII, fig. 4.)

The lateral cartilages are attached, one on each side, to the wings of the coffin bone by their inferior borders. They are thin plates of fibro-cartilage, and their function is to assist the frog and adjacent structures to regain their proper position after having been displaced by the weight of the body while the foot rested on the ground. (Plate XXXII, fig. 2.)

FAULTS OF CONFORMATION.

A large percentage of horses have feet which are not perfect in conformation, and as a consequence they are especially predisposed to certain injuries and diseases.

_Flatfoot_ is that condition in which the sole has little or no convexity. It is a peculiarity common to some breeds, especially heavy, lymphatic animals raised on low, marshy soils. It is confined to the fore feet, which are generally broad, low-heeled, and with a wall less upright than is seen in the perfect foot.

In flatfoot there can be little or no elasticity in the sole, for the reason that it has no arch, and the weight of the animal is received on he entire plantar surface, as it rests upon the ground instead of on the wall. For these reasons such feet are particularly liable to bruises of the sole, corns, pumiced sole, and excessive suppuration when the process is once established. Horses with flatfoot should be shod with a shoe having a wide web, pressing on the wall only, while the heels and frog are never to be pared. Flatfoot generally has weak walls, and as a consequence the nails of the shoe are readily loosened and the shoe cast.

_Clubfoot_ is a term applied to such feet as have the walls set nearly perpendicular. When this condition is present the heels are high, the fetlock joint is thrown forward, or knuckles, and the weight of the animal is received on the toes. Many mules are clubfooted, especially behind, where it seems to cause little or no inconvenience. Severe cases of clubfoot may be cured by cutting the tendons, but as a rule special shoeing is the only measure of relief that can be adopted. The toe should not be pared, but the heels are to be lowered as much as possible and a shoe put on with a long, projecting toe piece, slightly turned up, while the heels of the shoe are to be made thin.

_Crookedfoot_ is that condition in which one side of the wall is higher than the other. If the inside wall is the higher, the ankle is thrown outward, so that the fetlock joints are abnormally wide apart and the toes close together. Animals with this deformity are "pigeon-toed," and are prone to interfere, the inside toe striking the opposite fetlock. If but one foot is affected, the liability to interfere is still greater, for the reason that the fetlock of the perfect leg is nearer the center plane.

When the outside heel is the higher the ankle is thrown in and the toe turns out. Horses with such feet interfere with the heel. If but one foot is so affected, the liability to interfere is less than when both feet are affected, for the reason that the ankle of the perfect leg is not so near to the center plane. Such animals are especially liable to stumbling and to lameness from injury to the ligaments of the fetlock joints. This deformity is to be overcome by such shoeing as will equalize the disparity in length of walls, and by proper boots to protect the fetlocks from interfering.

INTERFERING.

An animal is said to interfere when one foot strikes the opposite leg, as it passes by, during locomotion. The inner surface of the fetlock joint is the part most subject to this injury, although, under certain conditions, it may happen to any part of the ankle. It is seen more often in the hind than in the fore legs. Interfering causes a bruise of the skin and deeper tissues, generally accompanied with an abrasion of the surface. It may cause lameness, dangerous tripping, and thickening of the injured parts. (See also p. 387.)

_Causes._--Faulty conformation is the most prolific cause of interfering. When the bones of the leg are so united that the toe of the foot turns in (pigeon-toed), or when the fetlock joints are close together and the toe turns out, when the leg is so deformed that the whole foot and ankle turn either in or out, interfering is almost sure to follow. It may happen, also, when the feet grow too long, from defective shoeing, rough or slippery roads, from the exhaustion of labor or sickness, swelling of the leg, high knee action, fast work, and because the chest or hips are too narrow.

_Symptoms._--Generally, the evidences of interfering are easily detected, for the parts are tender, swollen, and the skin broken. But very often, especially in trotters, the flat surface of the hoof strikes the fetlock without evident injury, and attention is directed to these parts only by the occasional tripping and unsteady gait. In such cases proof of the cause may be had by walking and trotting the animal, after first painting the inside toe and quarter of the suspected foot with a thin coating of chalk, charcoal, mud, or paint.

_Treatment._--When the trouble is due to deformity or faulty conformation it may not be possible to overcome the defect.

In such cases, and as well in those due to exhaustion or fatigue, the fetlock or ankle boot must be used. In many instances interfering may be prevented by proper shoeing. The outside heel and quarter of the foot on the injured leg should be lowered sufficiently to change the relative position of the fetlock joint by bringing it farther away from the center plane of the body, thereby permitting the other foot to pass by without striking.

A very slight change is often sufficient to effect this result. At the same time the offending foot should be so shod that the shoe may set well under the hoof at the point responsible for the injury. The shoe should be reset every three or four weeks.

When the cause has been removed, cold-water bandages to the injured parts will soon remove the soreness and swelling, especially in recent cases. If, however, the fetlock has become calloused from long-continued bruising, a Spanish-fly blister over the parts, repeated in two or three weeks if necessary, will aid in reducing the leg to its natural condition.

KNUCKLING, OR COCKED ANKLES.

Knuckling is a partial dislocation of the fetlock joint, in which the relative position of the pastern bone to the cannon and coronet bones is changed, the pastern becoming more nearly perpendicular, with the lower end of the cannon bone resting behind the center line of the large pastern, while the lower end of this bone rests behind the center line of the coronet. While knuckling is not always an unsoundness, it nevertheless predisposes to stumbling and to fracture of the pastern.

_Causes._--Young foals are quite subject to this condition, but in the great majority of cases it is only temporary. It is largely due to the fact that before birth the legs were flexed, and time is required after birth for the ligaments, tendons, and muscles to adapt themselves to the function of sustaining the weight of the body.

As they grow old, horses with erect pasterns are very prone to knuckle, especially in the hind legs. All kinds of heavy work, particularly in hilly districts, and fast work on hard race tracks or roads are exciting causes of knuckling. It is also commonly seen as an accompaniment of that faulty conformation called clubfoot, in which the toe of the wall is perpendicular and short, and the heels high--a condition most often seen in the mule, especially in the hind feet.

ANATOMY OF FOOT.]

ANATOMY OF FOOT.]

ANATOMY AND DISEASES OF THE FOOT.]

SOUND AND CONTRACTED FEET.]

Lastly, knuckling is produced by disease of the suspensory ligament or of the flexor tendons, whereby they are shortened, and by disease of the fetlock joints. (See p. 372.)

_Treatment._--In young foals no treatment is necessary, unless there is some deformity present, since the legs straighten up without interference in the course of a few weeks. When knuckling has commenced, the indications are to relieve the tendons and ligaments by proper shoeing. The foot is to be prepared for the shoe by shortening the toe as much as possible, leaving the heels high; or if the foot is prepared in the usual way the shoe should be thin in front, with thick heels or high calks. For the hind feet a long-heeled shoe with calks seems to do best. Of course, when possible, the causes of knuckling are to be removed; since this can not always be done, however, the time may come when the patient can no longer perform any service, particularly in those cases in which both fore legs are affected, and it becomes necessary either to destroy the animal or obtain relief by surgical interference. In such cases the tendons between the fetlock and knee may be divided for the purpose of obtaining temporary relief. Firing and blistering the parts responsible for the knuckling may, in some instances, effect a cure; but a consideration of these measures belongs properly to the treatment of the disease in which knuckling appears simply as a sequel.

WINDGALL.

Joints and tendons are furnished with sacs containing a lubricating fluid called synovia. When these sacs are overdistended by reason of an excessive secretion of synovia, they are called windgalls. They form a soft, puffy tumor about the size of a hickory nut, and are most often found in the fore leg, at the upper part of the fetlock joint, between the tendon and the shin bone. When they develop in the hind leg it is not unusual to see them reach the size of a walnut. Occasionally they appear in front of the fetlock on the border of the tendon. The majority of horses are not subject to them after colt-hood has passed. (See also p. 355.)

_Causes._--Windgalls are often seen in young, overgrown horses, in which the body seems to have outgrown the ability of the joints to sustain the weight. In cart and other horses used to hard work, in trotters with excessive knee action, in hurdle racers and hunters, and in most cow ponies there is a predisposition to windgalls. Street-car horses and others used to start heavy loads on slippery streets are the ones most liable to develop windgalls in the hind legs.

_Symptoms._--The tumor is more or less firm and tense when the foot is on the ground, but is soft and compressible when the foot is off the ground. In old horses windgalls generally develop slowly and cause no inconvenience. If they are caused by excessive tension of the joint the tumor develops rapidly, is tense, hot, and painful, and the animal is exceedingly lame. The patient stands with the joint flexed, and walks with short steps, the toe only being placed on the ground. When the tumor is large and situated upon the inside of the leg it may be injured by interfering, causing stumbling and inflammation of the sac. Rest generally causes the tumor to diminish in size, only to fill up again after renewed labor. In old cases the tumors are hardened, and may become converted into bone by a deposit of the lime salts.

_Treatment._--The large, puffy joints of suckling colts, as a rule, require no treatment, for as the animal grows older the parts clean up and after a time the swelling entirely disappears.

When the trouble is from an injury, complete rest is to be obtained by the use of slings and a high-heeled shoe. Cold-water douches should be used once or twice a day, followed by cold-water bandages, until the fever has subsided and the soreness is largely removed, when a blister is to be applied.

In old windgalls, which cause more or less stiffness, some relief may be had by the use of cold-compress bandages, elastic boots, or the red iodid of mercury blisters. Opening the sacs, as recommended by some authors, is of doubtful utility, and should be adopted only by the surgeon capable of treating the wound he has made. Enforced rest until complete recovery is effected should always be insisted upon, since a too early return to work is sure to be followed by relapse.

SPRAIN OF THE FETLOCK.

Sprain of the fetlock joint is most common in the fore legs, and, as a rule, affects but one at a time. Horses doing fast work, as trotters, runners, steeplechasers, hunters, cow ponies, and those that interfere, are particularly liable to this injury.

_Causes._--Horses knuckling at the fetlock, and all those with diseases which impair the powers of locomotion, such as navicular disease, contracted heels, sidebones, chronic laminitis, etc., are predisposed to sprains of the fetlock. It generally happens from a misstep, stumbling, or slipping, which results in the joint being extended or flexed to excess. The same result may happen where the foot is caught in a rut, a hole in a bridge, or in a car track, and the animal falls or struggles violently. Direct blows and punctured wounds may also set up inflammation of the joint.

_Symptoms._--The symptoms of sprain of the fetlock vary with the severity of the injury. If slight, there may be no lameness, but simply a little soreness, especially when the foot strikes on uneven ground and the joint is twisted a little. In more severe cases the joint swells, is hot and puffy, and the lameness may be so intense as to compel the animal to hobble on three legs. While at rest the leg is flexed at the joint affected, and the toe rests on the ground.

_Treatment._--If the injury is slight, cold-water bandages and a few days' rest are sufficient to effect recovery. When there is an intense lameness, swelling, etc., the leg should be placed under a constant stream of cold water, as described in the treatment for quittor. When the inflammation has subsided, a blister to the joint should be applied.

In some cases, especially in old horses long accustomed to fast work, the ligaments of the joints are ruptured, in whole or in part, and the lameness may last a long time. In these cases the joint should be kept completely at rest; this condition is best obtained by the application of plaster of Paris bandages, as in cases of fracture. As a rule, patients take kindly to this bandage, and, while wearing it, may be given the freedom of a roomy box or yard. If they are disposed to tear it off, or if sufficient rest can not otherwise be obtained, the patient must be kept in slings.

In the majority of instances the plaster bandage should remain on from two to four weeks. If the lameness returns when the bandage is removed, a new one should be put on. The swellings which always remains after the other evidences of the disease have disappeared, may be largely dissipated and the joint strengthened by the rise of the firing iron and blisters.

A joint once injured by a severe sprain never entirely regains its original strength, and is ever after particularly liable to a repetition of the injury.

RUPTURE OF THE SUSPENSORY LIGAMENT.

Sprain with or without rupture of the suspensory ligament may happen in either the fore or hind legs, and is occasionally seen in horses of all classes and at all ages. Old animals, however, and especially hunters, runners, and trotters, are the most subject to this injury, and with them the seat of the trouble is nearly always in one or both the fore legs. Horses used for heavy draft are more liable to have the ligament of the hind legs affected.

When the strain upon the suspensory ligament becomes too great, one or both of the branches may be torn from the sesamoid bones, one or both of the branches may be torn completely across, or the ligament may rupture above the point of division.

_Symptoms._--The most common injury to the suspensory ligament is sprain of the internal branch in one of the fore legs. The trouble is indicated by lameness, heat, swelling, and tenderness of the affected branch, beginning just above the sesamoid bone and extending obliquely downward and forward to the front of the ankle. If the whole ligament is involved, the swelling comes on gradually, and is found above the fetlock and in front of the flexor tendons. The patient stands or walks upon the toe as much as possible, keeping the fetlock joint flexed so as to relieve the ligament of tension.

When both branches are torn from their attachments to the sesamoids, or both are torn across, the lameness comes on suddenly and is most intense; the fetlock descends, the toe turns up, and, as the animal attempts to walk, the leg has the appearance of being broken off at the fetlock. These symptoms, followed by heat, pain, and swelling of the parts at the point of injury, will enable anyone to make a diagnosis.

_Treatment._--Sprain of the suspensory ligament, no matter how mild it may be, should always be treated by enforced rest of at least a month, and the application of cold douches and cold-water bandages, firmly applied until the fever has subsided, when a cantharides blister should be put on and repeated in two or three weeks if necessary. When rupture has taken place the patient should be put into slings and a constant stream of cold water allowed to trickle over the seat of injury until the fever is reduced. In the course of a week or ten days a plaster of Paris splint, such as is used in fractures, is to be applied and left on for a month or six weeks. When this is taken off, blisters may be used to remove the remaining soreness; but it is useless to expect a removal of all the thickening, for, in the process of repair, new tissue has been formed which will always remain.

In old cases of sprain the firing iron may often be used with good results. As a rule, severe injuries to the suspensory ligament incapacitate the subject for anything but slow, light work.

OVERREACH.

When the shoe of the hind foot strikes and injures the heel or quarter of the forefoot the horse is said to overreach. It rarely happens except when the animal is going fast; hence is most common in trotting and running horses. In trotters the accident generally happens when the animal breaks from a trot to a run. The outside heels and quarters are most liable to the injury.