Part 55

If the caustic injections prove successful, the discharge will become healthy and gradually diminish, so that by the end of the second week the fistulous tracts are closing up and the injections are made with much difficulty.

If, on the other hand, there is but little or no improvement after this treatment has been used for three weeks, it may reasonably be concluded that the operation for the removal of the lateral cartilage must be resorted to for the cure of the trouble. As this operation can be safely undertaken only by an expert surgeon, it will not be described in this connection.

THRUSH.

Thrush is characterized by an excessive secretion of unhealthy matter from the cleft of the frog. While all classes of horses are liable to this affection, it is more often seen in the common draft horse than in any other breed, owing to the conditions of servitude and not to the fault of the breed. Country horses are much less subject to the disease, except in wet, marshy districts, than are the horses used in cities and towns.

Causes.—The most common cause of thrush is the filthy condition of the stable in which the animal is kept. Mares are more liable to contract the disease in the hind feet when filth is the cause, while the gelding and stallion are more liable to develop it in the fore feet. Hard work on rough and stony roads may also induce the disease, as may a change from dryness to excessive moisture. The latter cause is often seen to operate in old track horses, whose feet are constantly soaked in the bathtub for the purpose of relieving soreness. Muddy streets and roads, especially where mineral substances are plentiful, excite this abnormal condition of the frog. Contracted heels, scratches, and navicular disease predispose to thrush, while by some a constitutional tendency is believed to exist among certain animals which otherwise present a perfect frog.

Symptoms.—At first there is simply an increased moisture in the cleft of the frog, accompanied with an offensive smell. After a time a considerable discharge takes place—thin, watery, and highly offensive, changing gradually to a thicker puriform matter, which rapidly destroys the horn of the frog. Only in old and severe cases is the patient lame and the foot feverish—cases in which the whole frog is involved in the diseased process.

Treatment.—Thrushes are to be treated by cleanliness, the removal of all exciting causes, and a return of the frog to its normal condition. As a rule, the diseased and ragged portions of horn are to be pared away and the foot poulticed for a day or two with boiled turnips, to which may be added a few drops of carbolic acid or a handful of powdered charcoal to destroy the offensive smell. The cleft of the frog and the grooves on its edges are then to be cleaned and well filled with dry calomel and the foot dressed with oakum and a roller bandage. If the discharge is profuse, the dressing should be changed daily; otherwise it may be left on two or three days. Where a constitutional taint is supposed to exist, with swelling of the legs, grease, etc., a purgative, followed by dram doses of sulphate of iron, repeated daily, may be prescribed. In cases where the growth of horn seems too slow a Spanish-fly blister applied to the heels is often followed by good results. Feet in which the disease is readily induced may be protected in the stable with a leather boot. If the thrush is but a sequel to other disease, a permanent cure may not be possible.

CANKER.

Canker of the foot is due to the rapid reproduction of a vegetable parasite. It not only destroys the sole and frog, but, by setting up a chronic inflammation in the deeper tissues, prevents the growth of a healthy horn by which the injury may be repaired. Heavy cart horses are more often affected than those of any other class.

Causes.—The essential element in the production of canker is the parasite; consequently the disease may be called contagious. As in all other diseases due to specific causes, however, the seeds of the disorder must find a suitable soil in which to grow before they are reproduced. It may be said, then, that the conditions which favor the preparation of the tissues for a reception of the seeds of this disease are simply predisposing causes.

The condition most favorable to the development of canker is dampness—in fact, dampness seems indispensable to the existence and growth of the parasite; the disease is rarely, if ever, seen in high, dry districts, and is much more common in rainy than in dry seasons. Filthy stables and muddy roads have been classed among the causes of canker; but it is very doubtful whether these conditions can do more than favor a preparation of the foot for the reception of the disease germ.

All injuries to the feet, by exposing the soft tissues, may render the animal susceptible to infection; but neither the injury nor the irritation and inflammation of the tissues which follow are sufficient to induce the disease.

For some unknown reason horses with lymphatic temperaments—thick skins, flat feet, fleshy frogs, heavy hair, and particularly with white feet and legs—are especially liable to canker.

Symptoms.—Usually, canker is confined to one foot; but it may attack two, three, or all of the feet at once; or, as is more commonly seen, the disease attacks first one then another, until all may have been successively affected. When the disease follows an injury which has exposed the soft tissues of the foot, the wound shows no tendency to heal, but instead there is secreted from the inflamed parts a profuse, thin, fetid, watery discharge, which gradually undermines and destroys the surrounding horn, until a large part of the sole and frog is diseased. The living tissues are swollen, dark colored, and covered at certain points with particles of new, soft, yellowish, thready horn, which are constantly undergoing maceration in the abundant liquid secretion by which they are immersed. As this secretion escapes to the surrounding parts, it dries and forms small, cheesy masses composed of partly dried horny matter, exceedingly offensive to the sense of smell. When the disease originates independently of an injury, the first evidences of the trouble are the offensive odor of the foot, the liquid secretion from the cleft and sides of the frog, and the rotting away of the horn of the frog and sole.

In the earlier stages there is no interference with locomotion, but later the foot becomes sensitive, particularly if the animal is used on rough roads, and, finally, when the sole and frog are largely destroyed the lameness is severe.

Treatment.—Since canker does not destroy the power of the tissues to produce horn, but rather excites them to an excessive production of an imperfect horn, the indications for treatment are to restore the parts to a normal condition, when healthy horn may again be secreted. In my experience, limited though it has been, the old practice of stripping off the entire sole and deep cauterization, with either the hot iron or strong acids, is not attended with uniformly good results.

I am of the opinion that recovery can generally be effected as surely and as speedily with measures which are less heroic and much less painful. True, the treatment of canker is likely to exhaust the patience, and sometimes the resources, of the attendant; but after all success depends more on the persistent application of simple remedies and great cleanliness than on the special virtues of any particular drug.

First, then, clean the foot with warm baths and apply a poultice containing powdered charcoal or carbolic acid. A handful of the charcoal or a tablespoonful of the acid mixed with the poultice serves to destroy much of the offensive odor. The diseased portions of horn are to be carefully removed with sharp instruments, until only healthy horn borders the affected parts. The edges of the sound horn are to be pared thin, so that the swollen soft tissues may not overlap their borders. With sharp scissors cut off all the prominent points on the soft tissues, shorten the walls of the foot, and nail on a broad, plain shoe. The foot is now ready for the dressings, and any of the many stimulating and drying remedies may be used; but it will be necessary to change frequently from one to another, until finally all may be tried.

The list from which a selection may be made comprises wood tar, gas tar, petroleum, creosote, phenic acid; sulphates of iron, copper, and zinc; chlorid of zinc, bichlorid of mercury, calomel, caustic soda, nitrate of silver, chlorid of lime; carbolic, nitric, and sulphuric acids.

In practice I prefer to give the newly shod foot a bath for an hour or two in a solution of the sulphate of iron made by adding 2 ounces of the powdered sulphate to a gallon of cold water. When the foot is removed from the bath it is dressed with oakum balls dipped in a mixture made of Barbados tar 1 part, oil of turpentine 8 parts, to which is slowly added 2 parts of sulphuric acid, and the mixture well stirred and cooled. The diseased parts being well covered with the balls, a pad of oakum sufficiently thick to cause considerable pressure is placed over them, and all are held in place by pieces of heavy tin fitted to slip under the shoe. The whole foot is now incased in a boot or folded gunny sack and the patient turned into a loose, dry box. The dressings are to be changed daily or even twice a day at first. When they are removed, all pieces of new horny matter which are now firmly adherent must be rubbed off with the finger or a tent of oakum. As the secretion diminishes, dry powders, such as calomel, sulphates of iron, copper, etc., may prove of most advantage. The sulphates should not be used pure, but are to be mixed with powdered animal charcoal in the proportion of one of the former to eight or ten of the latter. When the soft tissues are all horned over, the dressings should be continued for a time, weak solutions being used to prevent a recurrence of the disease. If the patient is run down in condition, bitter tonics, such as gentian, may be given in 2-dram doses twice a day and a liberal diet of grain allowed.

CORNS.

A corn is an injury to the living horn of the foot, involving the soft tissues beneath, whereby the capillary blood vessels are ruptured and a small quantity of blood escapes which, by permeating the horn in the immediate neighborhood, stains it a dark color. If the injury is continuously repeated, the horn becomes altered in character and the soft tissues may suppurate or a horny tumor develop. Corns always appear in the sole in the angle between the bar and the outside wall of the hoof. In many cases the laminae of the bar, of the wall, or of both, are involved at the same time.

Three kinds of corns are commonly recognized—the dry, the moist, and the suppurative—a division based solely on the character of the conditions which follow the primary injury.

The fore feet are almost exclusively the subjects of the disease, for two reasons: First, because they support a greater part of the body; secondly, because the heel of the fore foot during progression is first placed upon the ground, whereby it receives much more concussion than the heel of the hind foot, in which the toe first strikes the ground.

Causes.—It may be said that all feet are exposed to corns, and that even the best feet may suffer from them when conditions necessary to the production of the peculiar injury are present. The heavier breeds of horses generally used for heavy work on rough roads and streets seem to be most liable to this trouble. Mules rarely have corns.

Among the causes and conditions which predispose to corns may be named high heels, which change the natural relative position of the bones of the foot and thereby increase the concussion to which these parts are subject; contracted heels, which in part destroy the elasticity of the foot, increase the pressure upon the soft tissues of the heel, and render lacerations more easy; long feet, which by removing the frog and heels too far from the ground deprive them of necessary moisture; this, in turn, reduces the elastic properties of the horn and diminishes the transverse diameter of the heels; weak feet, or those in which the horn of the wall is too thin to resist the tendency to spread, whereby the soft tissues are easily lacerated. Wide feet with low heels are always accompanied with a flat sole whose posterior wings either rest upon the ground or the shoe, and as a consequence are easily bruised; at the same time the arch of the sole is so broad and flat that it can not support the weight of the body, and in the displacement which happens when the foot is rested upon the ground the soft tissues are liable to become bruised or torn.

It is universally conceded that shoeing, either as a direct or predisposing cause, is most prolific in producing corns. One of the most serious as well as the most common of the errors in shoeing is to be found in the preparation of the foot. Instead of seeking to maintain the integrity of the arch, the first thing done is to weaken it by freely paring away the sole; nor does the mutilation end here, for the frog, which is nature's main support to the branches of the sole and the heels, is also largely cut away. This not only permits of an excessive downward movement of the contents of the horny box, but it at the same time removes the one great means by which concussion of the foot is destroyed. As adjuncts to the foregoing errors must be added the faults of construction in the shoe and in the way it is adjusted to the foot. An excess of concavity in the shoe, extending it too far back on the heels, high calks, thin heels which permit the shoe to spring, short heels with a calk set under the foot, and a shoe too light for the animal wearing it or for the work required of him, are all to be avoided as causes of corns. A shoe so set so as to press upon the sole or one that has been on so long that the hoof has overgrown it until the heels rest upon the sole and bars becomes a direct cause of corns. Indirectly the shoe becomes the cause of corns when small stones, hard, dry earth, or other objects collect between the sole and shoe. Lastly, a rapid gait and excessive knee action, especially on hard roads, predispose to this disease of the feet.

Symptoms.—Ordinarily a corn induces sufficient pain to cause lameness. It may be intense, as seen in suppurative corn, or it may be but a slight soreness, such as that which accompanies dry corn. It is by no means unusual in chronic corns to see old horses apparently so accustomed to the slight pain which they suffer as not to limp at all. But they are generally very restless. They paw their bedding behind them at night and often refuse to lie down for a long rest. The lameness of this disease, however, can hardly be said to be characteristic, for the reason that it varies so greatly in intensity; but the position of the leg while the patient is at rest is generally the same in all cases. The foot is so advanced that it is relieved of all weight, and the fetlock is flexed until all pressure by the contents of the hoof is removed from the heels. In suppurative corn the lameness subsides or entirely disappears as soon as the abscess opens. When the injured tissues are much inflamed, as may happen in severe and recent cases, the heel of the affected side, or even the whole foot, is hot and tender to pressure. In dry corn and in most chronic cases all evidences of local fever are often wanting. It is in these cases that the patient goes well when newly shod, for the smith cuts away the sole over the seat of injury until all pressure by the shoe is removed and lowers the heels so that concussion is reduced to a minimum.

If a corn is suspected, the foot should be examined for increased sensibility of the inside heel. Tapping the heel of the shoe with a hammer and grasping the wall and bar between the jaws of pincers with moderate pressure will cause more or less flinching if the disease is present. For further evidence the shoe is removed and the heel cut away with the drawing knife. As the horn is pared out, not only the sole in the angle is found discolored, but in many instances the insensible laminae of the bar and wall adjacent are also stained with the escaped blood. In moist and suppurative corns this discoloration is less marked than in dry corn and even may be entirely wanting. In these cases the horn is soft, often white, and stringy or mealy, as seen in pumiced sole resulting from founder. When the whole thickness of the sole is discolored and the horn dry and brittle it is generally evidence that the corn is an old one and that the exciting cause has existed continuously. A moist corn differs from the dry one in that the injury is more severe. The parts affected are more or less inflamed, and the horn of the sole in the angle is undermined by a citron-colored fluid, which often permeates the injured sole and laminae, causing the horn to become somewhat spongy.

A suppurative corn differs from others in that the inflammation ends in suppuration. The pus collects at the point of injury and finally escapes by working its way between the sensitive and insensible laminae to the top of the hoof, where an opening is made between the wall and coronary band at or near the heels. This is the most serious form of corns, for the reason that it may induce gangrene of the plantar cushion, cartilaginous quittor, or caries of the coffin bone.

Treatment.—Since a diversity of opinion exists as to what measures must be adopted for the radical cure of corns, the author will advise the use of those which have proved most efficient in his hands.

As in all other troubles, the cause must be discovered, if possible, and removed. In the great majority of cases the shoeing is at fault. While sudden changes in the method of shoeing are not advisable, it may be said that all errors, either in the preparation of the foot, in the construction of the shoe, or in its application may very properly be corrected at any time. Circumstances may at times make it imperative that shoes be worn which are not free from objections; as, for instance, the shoe with a high calk; but in such cases it is considered that the injuries liable to result from the use of calks are less serious than those which are sure to happen for the want of them.

For a sound foot perfectly formed, a flat shoe, with heels less thick than the toe, and which rests evenly on the wall proper, is the best. In flat feet it is often necessary to concave the shoe as much as possible on the upper surface, so that the sole may not be pressed upon. If the heels are very low the heels of the shoe may be made thicker. If the foot is very broad and the wall light toward the heels, a bar shoe resting upon the frog will aid to prevent excessive tension upon the soft tissues when the foot receives the weight of the body. A piece of leather placed between the foot and shoe serves largely to destroy concussion, and its use is absolutely necessary on some animals to enable them to work.

Last among the preventive measures may be mentioned those which serve to maintain the suppleness of the hoof. The dead horn upon the surface of the sole not only retains moisture for a long time, but protects the living horn beneath from the effects of evaporation; for this reason the sole should be pared as little as possible. Stuffing the feet with flaxseed meal, wet clay, or other like substances, or damp dirt floors or damp bedding of tanbark, greasy hoof ointments, etc., are all means which may be used to keep the feet from becoming too dry and hard.