In most of cases of laminitis in the fore feet the animal persists in standing until he is nearly recovered. In other cases he as persistently lies, standing only when necessity seems to compel it, and then for as short a time as possible. If the recumbent position is once assumed, the relief experienced tempts the patient to seek it again; so we often find him down a greater part of the time. But this is not true of all cases; sometimes he will make the experiment, then cautiously guard against a repetition. Even in cases of enforced recumbency, he ofttimes takes advantage of the first opportunity and gets upon his feet, doggedly remaining there until again laid upon his side. How to explain this diversity of action I do not know; theoretically the recumbent position is the only appropriate one, except when complications exist, and the one which should give the most comfort, yet it is rejected by very many patients and, no doubt, for some good reason. It has been suggested as an explanation that when the animal gets upon his feet after lying for a time the suffering is so greatly augmented that the memory of this experience deters him from an attempted repetition. If this were true, the horse with the first attack must necessarily make the experiment before knowing the after effects of lying down, yet many remain standing without even an attempt at gaining this experimental knowledge.

The most-favored position of the animal when down is on the broadside, with the feet and legs extended. While in this position the general symptoms greatly subside; the respirations and pulse become almost normal; the temperature falls and the perspiration dries. It is with difficulty that he is made to rise. When he attempts it he gets up rapidly and "all of a heap," as it were, shifting quickly from one to the other foot until they become accustomed to the weight thrown upon them. Occasionally a patient will get up like a cow, rising upon the hind feet first. Although enforced exercise relieves the soreness to some extent, it is but temporary, for after a few minutes' rest it returns with all its former severity.

Both hind feet.—When only both hind feet are affected, they are, while standing, maintained in the same position as when only the fore ones are the subjects of the disease, but with an entirely different object in view. Instead of being there to receive weight, they are so advanced that the heels only may receive what little weight is necessarily imposed on them; the fore feet at the same time are placed well back beneath the body, where they become the main supports; the animal standing, as Williams describes it, "all of a heap."

Progression is even more difficult now than when the disease is confined to the anterior extremities. The fore feet are dubiously advanced a short distance and the hind ones brought forward with a sort of kangaroo hop that results in an apparent loss of equilibrium which the animal is a few moments in regaining. The general symptoms, or, in other words, the degree of suffering, seem more severe than when the disease affects the fore feet alone. The standing position is not often maintained, the patient seeking relief in recumbency. This fact is easily understood when we consider how cramped and unnatural is the position he assumes while standing and, if it were maintained for any considerable length of time, would, no doubt, excite the disease in the fore feet, as explained by D'Arboval.

All four feet.—Laminitis of all four feet is but uncommonly met with. The author has seen but three such cases. In all these the position assumed was nearly normal. All the feet were slightly advanced, and first one, then another, momentarily raised from the ground and carefully replaced, this action being kept up almost continually during the time the animal remained standing. The suffering is most acute, the appetite lost, and, although the patient lies most of the time, the temperature remains too high. The pulse and respirations are greatly accelerated, the body covered with sweat, and bed sores are unpleasant accompaniments.

Course.—The course which laminitis takes varies greatly in different cases, being influenced more or less by the exciting cause, the animal's previous condition, the acuteness of the attack, and the subsequent treatment. The first symptoms rarely exhibit themselves while the animal is at his work, although we occasionally see the gait impaired by stumbling, the body covered with a profuse sweat, and the respirations become blowing in character as premonitions of the oncoming disease; but, as a rule, nothing amiss with the animal is noted until he has stood for some time after coming in from work, when, in attempting to move him, he is found very stiff. Like all congestions, the early symptoms usually develop rapidly; yet this is not always the case, for often there appears to be no well-defined period of congestion, the disease seemingly commencing at a point and gradually spreading until a large territory is involved in the morbid process.

Simple congestion.—Those cases of simple congestion of the laminae, which we erroneously call laminitis, are rapidly developed, the symptoms are but moderately severe, and but one to three days are required for recovery. There are no structural changes and but a moderate exudate. This is rapidly reabsorbed, leaving the parts in the same condition as they were previous to the attack. If the congestion has been excessive, a rupture of some of the capillaries will be found, a condition more liable to exist if the animal is made to continue work after a development of symptoms has begun.

True, the majority of these last-described cases prove to be the laminitis in fact, yet the congestion may pass away and the extravasated blood be absorbed without inflammation sufficient to warrant calling it laminitis. The seat of greatest congestion will always be found in the neighborhood of the toe, because of the increased vascularity of that part, and, although at times it is limited to the podophyllous tissue alone, any or all parts of the keratogenous membrane may be affected by the congestion and followed finally by inflammation.

Acute.—In the acute form of laminitis the symptoms may all develop rapidly, or it may commence by the appearance of a little soreness of the feet which in 24 or 48 hours develops into a well-marked case. This peculiarity of development is due to one of two causes. Either the congestion is general, but takes place slowly, or it begins in one or more points and gradually spreads throughout the laminae. These acute cases generally run their course in from one to two weeks. Usually a culmination of the symptoms is reached, if the patient is properly treated, in from three to five days; then evidences of recovery are discernible in favorable cases. The lameness improves, the other symptoms gradually subside, and eventually health is regained. It is in these cases that a strong tendency to disorganization of a destructive character exists; hence it is we see so many recover imperfectly, with marked structural changes permanently remaining.

Subacute.—Subacute laminitis is most often seen as a termination of the acute form, although it may exist independent of or precede an acute attack. It is characterized by the mildness of its symptoms, slow course, and moderate tissue changes. It may be present a long time before any pathological lesions result other than those found in the acute form, and when these changes do take place they should be viewed rather as complications.

Chronic.—Chronic laminitis is a term used by many to designate any of the sequelae of the acute and subacute forms of this disease. Pure, chronic inflammation of the laminae is not very commonly met with, but is most frequent in horses that have long done fast track work. They have "fever in the feet" at all times and are continually sore, both conditions being aggravated by work. Like chronic inflammation of other parts, there is a strong tendency to the development of new connective tissue which, by its pressure upon the blood vessels, interferes with nutrition. Wasting of the coffin bone and inflammation of its covering with caries is not unusual. The continued fever and impaired function of secretion result in the production of a horn deficient in elasticity, somewhat spongy in character, and inclined to crumble. In some cases of "soreness" in horses used to hard or fast work there is evident weakness of the coats of the vessels, brought on by repeated functional exhaustion. Here slight work brings on congestion, which results in serous effusion and temporary symptoms similar to those of chronic laminitis.

Complications.—Complications concurrent with or supervening upon laminitis are frequent and varied, and are often dependent upon causes not fully understood.

Excessive purgation is one of the simplest of these, and not usually attended with dangerous consequences. It rarely occurs unless induced by a purgative, and the excessive action of the medicine is probably to be explained upon the theory that the mucous membrane sympathizes with the diseased laminae, is irritable, and readily becomes overexcited. The discharges are thin and watery, sometimes offensively odorous, and occasionally persist in spite of treatment. It may prove disastrous to the welfare of the patient by the rapid exhaustion which it causes, preventing resolution of the laminitis, and may even cause death.

Septicemia and pyemia.—Septicemia and pyemia are unusual complications and are seen only in the most severe cases in which bed sores are present or suppuration of the laminae results. They die, as a rule, within three days after showing signs of the complication.

Pneumonia.—the so-called metastatic—needs no special consideration, for in its lesions and symptoms it does not differ from ordinary pneumonia, although it may be overlooked entirely by the practitioner. Examinations of the chest should be made every day, so as to detect the disease at its onset and render proper aid.

Sidebones.—A rapid development of sidebones is one of the complications, or, perhaps better, a sequel of laminitis not often met with in practice. Here the inflammatory process extends to the lateral cartilages, with a strong tendency to calcification. The deposition of the lime salts is sometimes most rapid, so that the "bones" are developed in a few weeks; in other instances they are deposited slowly and their growth is not noted until long after the subsidence of the laminitis, so that the exciting cause is not suspected. This change in the cartilages may commence as early as the first of the laminitis; and although the trouble in the laminae is removed in the course of a fortnight the symptoms do not entirely subside, the animal retains the shuffling gait, the sidebones continue to grow, and the patient usually remains quite lame. This alteration of the cartilages generally prevents the patient from recovering his natural gait, and the practitioner receives unjust censure for a condition of affairs he could neither foresee nor prevent.

The laminitic process occasionally extends to the covering of the coronet bone, or at least concurrent with and subsequent to laminitis the development of "low ringbone" is seen, and it is apparently dependent upon the disease of the laminae for its exciting cause. The impairment of function and consequent symptoms are much less marked here than in sidebones. The coronet remains hot and sensitive and somewhat thickened after the laminitis subsides, and a little lameness is present. This lameness persists, and the deposits of new bone may readily be detected.

Suppuration of the sensitive membrane is a somewhat common complication, and even when present in its most limited form is always a serious matter; but when it becomes extensive, and especially when the suppurative process extends to the periosteum, the results are liable to be fatal. When suppuration occurs the exudation does not appear to be excessive. It is rich in leucocytes and seems to have caused detachment of the sensitive tissues from the horn prior to the formation of pus in some instances; in others the tissues are still attached to the horn, and the suppuration takes place in the deeper tissues.

Limited suppuration may take place in any part of the sensitive tissues of the foot during laminitis, and may ultimately be reabsorbed instead of being discharged upon the surface, but generally the process begins in the neighborhood of the toe and spreads backward and upward toward the coronet, finally separating the horn from the coronary band at the quarters. At the same time it spreads over the sole and eventually the entire hoof is loosened and sloughs away, leaving the tissues beneath entirely unprotected. In other instances—and these are generally the cases not considered unusually severe—the suppuration begins at the coronary band. It extends but a short distance into the tissues, yet destroys the patient by separating the hoof from the coronary band, upon which it depends for support and growth. This form of the suppurative process usually begins in front. It is this part of the coronary band that is always most actively affected with inflammation, and consequently it is here that impairments first occur.

Suppuration of the sensitive sole is more common than of the sensitive laminae and coronary band. It is present in the majority of cases in which there is a dropping of the coffin bone, and in other instances when the effusion at this point is so great as to arrest the production of horn and uncover the sensitive tissues. Except when the result of injury it begins at the toe and spreads backward, and, if not relieved by opening the sole, escapes at the heel. Suppuration of the sole is much less serious than in other parts of the foot.

If the acute constitutional symptoms developed from sloughing of the foot do not result in death, a new hoof of very imperfect horn may be developed after a time; but unless the animal is to be kept for breeding purposes alone the foot will ever be useless for work and death should relieve the suffering. When only the sole sloughs, recovery takes place with proper treatment.

Peditis.—This is the term that Williams applies to that serious complication of laminitis in which not only the laminae, but the periosteum membrane covering the bone and coffin bone also are subjects of the inflammatory process. Neither is this all; in some of these cases of peditis acute inflammation of the coffin joint is present, and occasionally suppuration of the joint. A mild form of periostitis, in which the exudation is in the outer layer of the periosteum only, is a more common condition than is recognized generally by practitioners. Intimate contiguity of structures is the predisposing cause, for the disease either spreads from the original seat or the complication occurs as one of the primary results of the exciting cause. In the severer cases in which the exudate separates the periosteum from the bone, suppuration, gangrene, and superficial caries are common results. If infiltration of the bone tissues is rapid the blood supply is cut off by pressure upon the vessels and death of the coffin bone follows. Grave constitutional symptoms mark these changes, which soon prove fatal.

In the mild cases of periostitis it is by no means easy positively to determine its presence, for there are no special symptoms by which it may be distinguished from pure laminitis. In a majority of acute cases, though, which show no signs of improvement by the fifth to seventh day, it is safe to suspect periostitis, particularly if the coronets are very hot, the pulse full and hard, and the lameness acute. In the fortunately rare cases in which the bone is affected with inflammation and suppuration the agony of the patient is intense; he occupies the recumbent position almost continually, never standing for more than a few minutes at a time; suffers from the most careful handling of the affected feet; maintains a rapid pulse and respiration, high temperature, loss of appetite, and great thirst. It is in these cases that the patient continually grows worse, and the appearance of suppuration at the top of the hoof in about two weeks after the inception of the disease proves the inefficiency of any treatment which may have been used and the hopelessness of the case. These patients die usually between the tenth and twentieth days either from exhaustion or pyemic infection.

Gangrene occurs in the periosteum as the result of excessive detachment from the bone and compression due to excessive exudation. Other parts of the sensitive tissues are subject occasionally to the same fate, and at times large areas will be found dead.

Pumiced sole is that condition in which the horny sole in the neighborhood of the toe readily crumbles away and leaves the sensitive tissues more or less exposed. It is not a complication of laminitis only, for it is seen under other conditions. Williams has described the horny tissue of pumiced sole as "weak, cheesy, or spongy, like macerated horn, or even grumous (thick, clotted)." Crumbling horn, when critically examined, shows almost an entire absence of the cohesive matter which unites the healthy fibers, while the fibers themselves are irregular and granular in appearance. Pumiced sole depends upon an impairment of the horn-secreting powers of the sensitive sole or upon a separation of the horny from the soft tissues which maintain its vitality.

Punctured wounds of the foot, accompanied with any considerable destruction of the soft tissues, present the same peculiarities of horn in the immediate neighborhood of the injury. Bruises of the sole are followed by this change when the exudation has been excessive and has separated the horn from the living tissues. True, in these cases we rarely see the soft tissues laid bare, for the reason that new horn is constantly secreted and replaces that undergoing disintegration.

Laminitis presents three conditions under which pumiced sole may appear: First, when free exudation separates the horn from the other tissues, or when the process of inflammation arrests the production of horn by impairing or destroying the horn-secreting membrane; second, when depression of the coffin bone causes pressure upon and arrests the formation of horn; and, third, when the elevation of the sole compresses the soft tissues against the pedal bone and induces the same condition.

Pumiced sole, from simple exudation and separation of tissues, is of little importance for the reason given above in connection with bruises; but when suppuration occurs in restricted portions of the foot in conjunction with laminitis, it always lays bare the tissues beneath and temporarily impairs the animal's value. Recovery takes place after a few weeks by the tissues "horning over," as in injuries attended by the same process. Depression of the coffin bone is not sufficient within itself to cause pumiced sole; for, if the relative change in the bone takes place slowly, or if the horn is thin, the sole becomes convex from gradual pressure and the soft tissues adapt themselves to the change without having their function materially impaired. But when the dropping is sudden and the soft tissues are destroyed, the horn rapidly crumbles away and the toe of the bone comes through. In many of these cases the soft tissues remain uncovered for months. When they are eventually covered it is with a thin, slightly adherent horn that stands but little or no wear. The sole being now convex, the diseased tissues bear unusual weight by coming in contact with the ground, and hence it is that these animals are generally incurable cripples.

In most cases in which the sole is raised to meet the pedal bone and pumiced sole occurs it is due not to pressure of the bone from within (for the tissues are capable of adapting themselves to the gradual change) but to impaired vitality of the sensitive tissues from the inflammation and to the constant concussion and pressure applied from without during progression. To this is to be added the paring away of the horn when applying the shoe, thereby keeping the sole at this point too thin.

Turning up of the toe.—In many cases of laminitis which have become chronic it is found that the toe of the foot turns up; that the heels are longer than natural; while the hoof near the coronary band is circled with ridges like the horn of a ram. Even in cases in which recovery has taken place, and in other diseases than laminitis, these ridges may be found in the wall of the foot. In such cases, however, the ridges are equally distant from one another all around the foot, while in turning up of the toe the ridges are wide apart at the heels and close together in front, as seen in the figure. (Plate XXXVII, fig. 4.) These ridges are produced by periods of interference with the growth of horn alternating with periods during which a normal or nearly normal growth takes place. When the toe turns up it is because the coronary band in front produces horn very slowly, while at the heels it grows much faster, causing marked deformity.

Animals so affected always place the abnormally long heel first upon the ground, not alone because the heel is too long, nor as in acute or subacute laminitis to relieve the pain, but for the reason that the toe is too short and lifted away from its natural position. To bring the toe to the ground the leg knuckles at the fetlock joint.

The pain and impairment of function in these cases always result in marked atrophy of the muscles of the forearm and shoulder, and to some extent of the pectorals, while the position of the fore legs advances the shoulder joints so far forward as to cause a sunken appearance of the breast, which the laity recognize as "chest founder."

The lesions of turning up of the toe are permanent, and are the most interesting pathologically of all the complications of laminitis.

Treatment.—The treatment of laminitis is probably more varied than of any other disease, and yet a large number of cases recover for even the poorest practitioner.

Prevention.—To guard against and prevent disease, or to render an unpreventable attack less serious than it otherwise would be, is the highest practice of the healing art. In a disease so prone to result from the simplest causes, especially when the soundest judgment may not be able to determine the extent of the disease-resisting powers of the tissues which are liable to be affected, or of what shall in every instance constitute an overexcitement, it is not strange that horse owners find themselves in trouble from unintentional transgression. If the disease were dependent upon specific causes, or if the stability of the tissues were of a fixed or more nearly determinate quality, some measures might be instituted that would prove generally preventive; but the predisposing causes are common conditions and often can not be remedied. That which is gentle work in one instance may incite disease in another. That which is feed to-day may to-morrow prove disastrous to health. Finally, necessary medical interference, no matter how judicious, may cause a more serious complaint than that which was being treated. Notwithstanding these difficulties there are some general rules to be observed that will in part serve to prevent the development of an unusual number of cases. First of all the predisposing causes must be removed when possible; when impossible, unusual care must be taken not to bring an exciting cause into operation. Under no circumstances should fat animals have hard work. If the weather is warm or the variation of temperature great, all horses should have but slow, gentle labor until they become inured to it, the tissues hardened, and their excitability reduced to a minimum. Green horses should have moderate work, particularly when taken from the farm and dirt roads to city pavements; for under these circumstances increased concussion, changed hygienic conditions, and artificial living readily become active causes of the disease. Army horses just out of winter quarters, track horses with insufficient preparation, and farmers' horses put to work in the spring are among the most susceptible classes, and must be protected by work that is easy and gradual. If long marches or drives are imperative, the incumbrances must be as light as possible and the journey interspersed with frequent rests, for this allows the laminae to regain their impaired functional activity and to withstand much more work without danger. Furthermore, it permits early detection of an attack, and prevents working after the disease begins, which renders subsequent medication more effective by cutting the process short at the stage of congestion.

All animals when resting immediately after work should be protected from cold air or drafts. If placed in a stable that is warm and without draft, no covering is necessary; under opposite conditions blankets should be used until the excitement and exhaustion of labor have entirely passed away. It is still better that all animals coming in warm from work be "cooled out" by slow walking until the perspiration has dried and the circulation and respiration are again normal. Animals stopped on the road even for a few moments should always be protected from rapid change of temperature by appropriate clothing. If it can be avoided, horses that are working should never be driven or ridden through water. If unavoidable, they should be cooled off before passing through, and then kept moving until completely dried. The same care is to be practiced with washing the legs in cold water when just in from work, for occasionally it proves to be the cause of a most acute attack of this disease. Unusual changes in the manner of applying the shoes should not be hastily made. If a plane shoe has been worn, high heels or toes must not be substituted at once; but the change, if necessary, should gradually be made, so that the different tissues may adapt themselves to the altered conditions. If radical changes are imperative, as is sometimes the case, the work must be so reduced in quantity and quality that it can not excite the disease.

Laminitis from the effects of purgatives can scarcely be guarded against. I can not determine from the cases in which I have seen this result that there are any conditions present that would warn us of danger. The trouble does not seem to depend upon the size of the purgative, the length of time before purgation begins, or the activity and severity with which the remedy acts. Medicines known to have unusually irritating effects on the alimentary canal should be used only when necessity demands it, and then in moderate doses.

Experience alone will determine what animals are liable to suffer from this disease through the use of feeds. When an attack can be ascribed to any particular feed it should be withheld, unless in small quantities. Horses that have never been fed upon Indian corn should receive but a little of it at a time, mixed with bran, oats, or other feed, until it has been determined that no danger exists. Corn is less safe in warm than in cold weather, and for this reason it should always be fed with caution during spring and summer months.

When an animal is excessively lame in one foot the shoe of the opposite member should be removed, and cold water frequently applied to the well foot. At the same time, if the subject remains standing, the slings should be used. Horses should under no circumstances be overworked; to guard against this, previous work, nature of roads, state of weather, and various other influences must be carefully considered. Watering while warm is a pernicious habit, and, unless the animal is accustomed to it, is liable to result in some disorder, ofttimes in laminitis.

Curative measures.—In cases of simple congestion of the laminae the body should be warmly clothed and warm drinks administered. The feet should be placed in a warm bath to increase the return flow of blood. In course of an hour the feet may be changed to cold water and kept there until recovery is completed. If the constitutional symptoms demand it, diuretics should be given. Half-ounce doses of saltpeter three times a day in the water answer the purpose. In cases of active congestion the warm footbaths should be omitted and cold ones used from the commencement. Subacute laminitis demands the same treatment, with laxatives if there is constipation, and the addition of low-heeled shoes. The diuretics may need to be continued for some time and their frequency increased. Regarding acute laminitis, what has been called the "American treatment" is simple and efficient. It consists solely in the administration of large doses of nitrate of potash and the continued application to the feet and ankles of cold water.

Three to four ounces of saltpeter in a pint of water, repeated every six hours, is a proper dose. The laminitis frequently subsides within a week. These large doses may be continued for a week without danger. Under no circumstances have I seen the kidneys irritated to excess or other unfavorable effects produced.

The feet should be kept in a tub of water at a temperature of 45 deg. to 50 deg. F., unless the animal is lying down, when swabs are to be used and wet every half hour with the cold water. The water keeps the horn soft and moist and acts directly upon the inflamed tissues by reducing the temperature. Cold maintains the vitality and disease-resisting qualities of the soft tissues, tones up the coats of the blood vessels, diminishes the supply of blood, and limits the exudation. Furthermore, it has an anesthetic effect upon the diseased tissues and relieves the pain.

Aconite may be given in conjunction with the niter when the heart is greatly excited and beats strongly. Ten-drop doses, repeated every 2 hours for 24 hours, are sufficient. The use of cathartics is dangerous, for they may excite superpurgation. Usually the niter will relieve the constipation; yet if it should prove obstinate, laxatives may be carefully given. Bleeding, both general and local, should be guarded against. The shoes must be early removed and the soles left unpared.

Paring of the soles presents two objections: First, while it may temporarily relieve the pain by relieving pressure, it favors greater exudation, which may more than counterbalance the good effects. Secondly, it makes the feet tender and subject to bruises when the animal again goes to work. The shoes should be replaced when convalescence sets in and the animal is ready to take exercise. Exercise should never be enforced until the inflammation has subsided; for although it temporarily relieves the pain and soreness it maintains the irritation, increases the exudation, and postpones recovery.

If at the end of the fifth or sixth day prominent symptoms of recovery are not apparent, apply a stiff blister of cantharides around the coronet and omit the niter for about 48 hours. When the blister is well set, the feet may again receive wet swabs. If one blister does not remove the soreness it may be repeated, or the actual cautery applied. The same treatment should be adopted where sidebones form or inflammation of the coronet bone follows. When the sole breaks through, exposing the soft tissues, the feet must be carefully shod with thin heels and thick toes if there is a tendency to walk on the heels, and the sole must be well protected with appropriate dressings and pressure over the exposed parts. When there is turning up of the toe, blistering of the coronet, in front only, sometimes stimulates the growth of horn, but as a rule judicious shoeing is the only treatment that will enable the animal to do light, slow work.

When suppuration of the laminae is profuse, it is better to destroy your patient at once and relieve his suffering: but if the suppuration is limited to a small extent of tissue, especially of the sole, treatment, as in acute cases, may induce recovery and should always be tried. If from bed sores or other causes septicemia or pyemia is feared, the bisulphite of soda, in half-ounce doses, may be given in conjunction with tonics and such other treatment as is indicated in these diseases.

As to enforced recumbency I doubt the propriety of insisting on it in the majority of cases, for I think the patient usually assumes whatever position gives most comfort. No doubt recumbency diminishes the amount of blood sent to the feet, and may greatly relieve the pain, so that forcing the patient to lie down may be tried, yet should not be renewed if he thereafter persists in standing.

When the animal persistently stands, or constant lying indicates it (to prevent extensive sores), the patient should be placed in slings. When all four feet are affected it may be impossible to use slings, for the reason that the patient refuses to support any of his weight and simply hangs in them. Lastly, convalescent cases must not be returned to work too early, else permanent recovery may never be effected.



DISEASES OF THE SKIN.

By JAMES LAW, F. R. C. V. S.,

Formerly Professor of Veterinary Science, etc., Cornell University.

As we find them described in systematic works, the diseases of the skin are very numerous and complex, which may be largely accounted for by the fact that the cutaneous covering is exposed to view at all points, so that shades of difference in inflammatory and other diseased processes are easily seen and distinguished from one another. In the horse the hairy covering serves to some extent to mask the symptoms, and hence the nonprofessional man is tempted to apply the term "mange" to all alike, and it is only a step further to apply the same treatment to all these widely different disorders. Yet even in the hairy quadruped the distinction can be made in a way which can not be done in disorders of that counterpart and prolongation of the skin—the mucous membrane, which lines the air passages, the digestive organs, the urinary and generative apparatus. Diseased processes, therefore, which in these organs it might be difficult or impossible to distinguish from one another, can usually be separated and recognized when appearing in the skin.

Nor is this differentiation unimportant. The cutaneous covering presents such an extensive surface for the secretion of cuticular scales, hairs, horn, sebaceous matter, sweat, and other excretory matters, that any extensive disorder in its functions may lead to serious internal disease and death. Again, the intimate nervous sympathy of different points of the skin with particular internal organs renders certain skin disorders causative of internal disease and certain internal diseases causative of affections of the skin. The mere painting of the skin with an impermeable coating of glue is speedily fatal; a cold draft striking on the chest causes inflammation of the lungs or pleura; a skin eruption speedily follows certain disorders of the stomach, the liver, the kidneys, or even the lungs; simple burns of the skin cause inflammations of internal organs, and inflammation of such organs cause in their turn eruptions on the skin. The relations—nervous, secretory, and absorptive—between the skin and internal organs are most extensive and varied, and therefore a visible disorder in the skin may point at once and specifically to a particular fault in diet, to an injudicious use of cold water when the system is heated, to a fault in drainage, ventilation, or lighting of the stables, to indigestion, to liver disease, to urinary disorder, etc.



STRUCTURE OF THE SKIN.

The skin consists primarily of two parts: (1) The superficial nonvascular (without blood vessels) layer, the cuticle, or epidermis; and (2) the deep vascular (with blood vessels) layer, the corium, dermis, or true skin. (See Pl. XXXVIII, fig. 1.)

The cuticle is made up of cells placed side by side and more or less modified in shape by their mutual compression and by surface evaporation and drying. The superficial stratum consists of the cells dried in the form of scales, which fall off continually and form dandruff. The deep stratum (the mucous layer) is formed of somewhat rounded cells with large central nuclei, and in colored skin containing numerous pigment granules. These cells have prolongations, or branches, by which they communicate with one another and with the superficial layer of cells in the true skin beneath. Through these prolongations they receive nutrient liquids for their growth and increase, and pass on liquids absorbed by the skin into the vessels of the true skin beneath. The living matter in the cells exercises an equally selective power on what they shall take up for their own nourishment and on what they shall admit into the circulation from without. Thus, certain agents, like iodin and belladonna, are readily admitted, whereas others, like arsenic, are excluded by the sound, unbroken epidermis. Between the deep and superficial layers of the epidermis there is a thin, translucent layer (septum lucidum) consisting of a double stratum of cells, and forming a medium of transition from the deep spheroidal to the superficial scaly cuticle.

The true skin, or dermis, has a framework of interlacing bundles of white and yellow fibers, large and coarse in the deeper layers, and fine in the superficial, where they approach the cuticle. Between the fibrous bundles are left interspaces which, like the bundles, become finer as they approach the surface, and inclose cells, vessels, nerves, glands, gland ducts, hairs, and in the deeper layers fat.

The superficial layer of the dermis is formed into a series of minute, conical elevations, or papillae, projecting into the deep portion of the cuticle, from which they are separated by a very fine transparent membrane. This papillary layer is very richly supplied with capillary blood vessels and nerves, and is at once the seat of acute sensation and the point from which the nutrient liquid is supplied to the cells of the cuticle above. It is also at this point that the active changes of inflammation are especially concentrated; it is the immediately superposed cell layers (mucous) that become morbidly increased in the earlier stages of inflammation; it is on the surface of the papillary layer that the liquid is thrown out which raises the cuticle in the form of a blister, and it is at this point mainly that pus forms in the ordinary pustule.

The fibrous bundles of the true skin contain plain, muscular fibers, which are not controlled by the will, but contract under the influence of cold and under certain nervous influences, as in some skin diseases and in the chill of a fever, and lead to contraction, tightening, or corrugation of the skin, contributing to produce the "hidebound" of the horseman. Other minute, muscular filaments are extended from the surface of the dermis to the hair follicle on the side to which the hair is inclined, and under the same stimulating influences produce that erection of the hair which is familiarly known as "staring coat." Besides these, the horse's skin is furnished with an expansion of red, voluntary muscle, firmly attached to the fibrous bundles, and by which the animal can not only dislodge insects and other irritants, but even shake off the harness. This fleshy envelope covers the sides of the trunk and the lower portions of the neck and head, the parts unprotected by the mane and tail, and serves to throw the skin of these parts into puckers, or ridges, in certain irritating skin diseases.

The hairs are cuticular products growing from an enlarged papilla lodged in the depth of a follicle or sac, hollowed out in the skin and extending to its deepest layers. The hair follicle is lined by cells of epidermis, which at the bottom are reflected on the papilla and become the root of the hair. The hair itself is formed of the same kind of cells firmly adherent to one another by a tough, intercellular substance, and overlapping each other, like slates on a roof, in a direction toward the free end.

The sebaceous glands are branching tubes ending in follicles or sacs and opening into the hair follicles, lined by a very vascular fibrous network representing the dermis, and an internal layer of cells representing the mucous layer of the cuticle. The oily secretion gives gloss to the hair and prevents its becoming dry and brittle, and keeps the skin soft and supple, protecting it at once against undue exhalation of water and undue absorption when immersed in that medium. Besides those connected with the hair follicles there are numerous, isolated, sebaceous glands, opening directly on the surface of the skin, producing a somewhat thicker and more odorous secretion. They are found in large numbers in the folds of the skin, where chafing would be liable if the surface were dry, as on the sheath, scrotum, mammary glands, and inner side of the thigh, around the anus and vulva, in the hollow of the heel, beneath the fine horn of the frog, on the inner side of the elbow, on the lips, nostrils, and eyelids. When closed by dried secretion or otherwise these glands may become distended so as to form various-sized swellings on the skin, and when inflamed they may throw out offensive, liquid discharges, as in "grease," or produce red, tender fungous growths ("grapes.")

The sweat glands of the horse, like those of man, are composed of simple tubes, which extend down through the cuticle and dermis in a spiral manner, and are coiled into balls in the deeper layer of the true skin. In addition to their importance in throwing offensive waste products out of the system, these glands tend to cool the skin and the entire economy of the animal through the evaporation of their watery secretion. Their activity is therefore a matter of no small moment, as besides regulating the animal heat and excreting impurities, they influence largely the internal organs through the intimate sympathy maintained between them and the skin.

Diseases of the skin may be conveniently divided, according to their most marked features, into—

(1) Those in which congestion and inflammation are the most marked features, varying according to the grade or form into (a) congestion with simple redness, dryness, and heat, but no eruption (erythema); (b) inflammation with red-pointed elevations, but no blisters (papules); (c) inflammation with fine, conical elevations, each surmounted by a minute blister (vesicle); (d) inflammation with a similar eruption but with larger blisters, like half a pea and upwards (bullae); (e) inflammation with a similar eruption, but with a small sac of white, creamy pus on the summit of each elevation (pustules); (f) the formation of pustules implicating the superficial layer of the true skin, a small portion of which dies and is thrown off as a slough, or "core" (boils); (g) the formation of round, nodular, transient swellings in the true skin (tubercles); and (h) the excessive production of scales, or dandruff (scaly or squamous affections).

(2) Diseases in which there are only deranged sensations of itching, heat, tenderness, etc. (neurosis).

(3) Diseased growths, such as warts, callosities, horny growths, cancer, etc.

(4) Diseases from parasites, animal and vegetable.

(5) Diseases connected with a specific poison, such as horsepox, erysipelas, anthrax, farcy, or cutaneous glanders, etc.

(6) Physical injuries, like wounds, burns, scalds, etc.

CONGESTION (RED EFFLORESCENCE, OR ERYTHEMA).

This is a congested or slightly inflamed condition of the skin, unattended with any eruption. The part is slightly swollen, hot, tender, or itchy, and dry, and if the skin is white there is redness. The redness is effaced by pressure, but reappears instantly when it is removed. Except in transient cases the hairs are liable to be shed. It may be looked on as the first stage of inflammation, and therefore when it becomes aggravated it may merge in part or in whole into a papular, vesicular, or pustular eruption.

Erythema may arise from a variety of causes, and is often named in accordance with its most prominent cause. Thus the chilling, or partial freezing, of a part will give rise to a severe reaction and congestion. When snowy or icy streets have been salted this may extend to severe inflammation, with vesicles, pustules, or even sloughs of circumscribed portions of the skin of the pastern (chilblain, frost-bite). Heat and burning have a similar effect, and this often comes from exposure to the direct rays of the sun. The skin that does not perspire is the most subject, and hence the white face or white limb of a horse becoming dried by the intensity of the sun's rays often suffers to the exclusion of the rest of the body (white face and foot disease). The febrile state of the general system is also a potent cause; hence the white-skinned horse is rendered the more liable if kept on a heating ration of buckwheat, or even of wheat or maize. Contact of the skin with oil of turpentine or other essential oils, with irritant liquids, vegetable or mineral, with rancid fats, with the acrid secretions of certain animals, like the irritating toad, with pus, sweat, tears, urine, or liquid feces, will produce congestion or even inflammation. Chafing is a common cause, and is especially liable to affect the fat horse between the thighs, by the side of the sheath or scrotum, on the inner side of the elbow, or where the harness chafes on the poll, shoulder, back, breastbone, and under the tail. The accumulation of sweat and dust between the folds of the skin and on the surface of the harness, and the specially acrid character of the sweat in certain horses, contribute to chafing or "intertrigo." The heels often become congested owing to the irritation caused by the short, bristly hairs in clipped heels. Again, congestion may occur from friction by halter, harness, or other foreign body under the pastern, or inside the thigh or arm, or by reason of blows from another foot (cutting, interfering, overreach). Finally, erythema is especially liable to occur in spring, when the coat is being shed, and the hair follicles and general surface are exposed and irritable in connection with the dropping of the hairs.

If due only to a local irritant, congestion will usually disappear when the cause has been removed, but when the feeding or system is at fault these conditions must be first corrected. While the coat is being shed the susceptibility will continue, and the aim should be to prevent the disease from developing and advancing so as to weaken the skin, render the susceptibility permanent, and lay the foundation of persistent or frequently recurring skin disease. Therefore at such times the diet should be nonstimulating, any excess of grain, and above all of buckwheat, Indian corn, or wheat, being avoided. A large grain ration should not be given at once on return from hard work, when the general system and stomach are unable to cope with it; the animal should not be given more than a swallow or two of cold water when perspiring and fatigued, nor should he be allowed a full supply of water just after his grain ration; he should not be overheated or exhausted by work, nor should dried sweat and dust be allowed to accumulate on the skin or on the harness pressing on it. The exposure of the affected heels to damp, mud, and snow, and, above all, to melting snow, should be guarded against; light, smooth, well-fitting harness must be obtained, and where the saddle or collar irritates an incision should be made in them above and below the part that chafes, and, the padding between having been removed, the lining should be beaten so as to make a hollow. A zinc shield in the upper angle of the collar will often prevent chafing in front of the withers.

Treatment.—Wash the chafed skin and apply salt water (one-half ounce to the quart), extract of witch-hazel, a weak solution of oak bark, or camphorated spirit. If the surface is raw use bland powders, such as oxid of zinc, lycopodium, starch, or smear the surface with vaseline, or with 1 ounce of vaseline intimately mixed with one-half dram each of opium and sugar of lead. In cases of chafing rest must be strictly enjoined. If there is constitutional disorder or acrid sweat, 1 ounce cream of tartar or a teaspoon of bicarbonate of soda may be given twice daily.

CONGESTION, WITH SMALL PIMPLES, OR PAPULES.

In this affection there is the general blush, heat, etc., of erythema, together with a crop of elevations from the size of a poppy seed to a coffee bean, visible when the hair is reversed or to be felt with the finger where the hair is scanty. In white skins they vary from the palest to the darkest red. All do not retain the papular type, but some go on to form blisters (eczema, bullae) or pustules, or dry up into scales, or break out into open sores, or extend into larger swellings (tubercles). The majority, however, remaining as pimples, characterize the disease. When very itchy the rubbing breaks them open, and the resulting sores and scales hide the true nature of the eruption.

The general and local causes may be the same as for erythema, and in the same subject one portion of the skin may have simple congestion and another adjacent papules. As the inflammatory action is more pronounced, so the irritation and itching are usually greater, the animal rubbing and biting himself severely. This itching is especially severe in the forms which attack the roots of the mane and tail, and there the disease is often so persistent and troublesome that the horse is rendered virtually useless.

The bites of insects often produce a papular eruption, but in many such cases the swelling extends wider into a buttonlike elevation, one-half to an inch in diameter. The same remarks apply to the effects of the poison ivy and poison sumac.

Treatment.—In papular eruption first remove the cause, then apply the same general remedies as for simple congestion. In the more inveterate cases use a lotion of one-half ounce sulphid of potassium in 2 quarts of water, to which a little Castile soap has been added, or use a wash with one-half ounce oil of tar, 2 ounces Castile soap, and 20 ounces water.

INFLAMMATION WITH BLISTERS, OR ECZEMA.

In this the skin is congested, thickened, warm (white skins are reddened), and shows a thick crop of little blisters formed by effusions of a straw-colored fluid between the true skin and the cuticle. The blisters may be of any size from a millet seed to a pea, and often crack open and allow the escape of the fluid, which concretes as a slightly yellowish scab or crust around the roots of the hairs. This exudation and the incrustation are especially common where the hairs are long, thick, and numerous, as in the region of the pastern of heavy draft horses. The term eczema is now applied very generally to eruptions of all kinds that depend on internal disorders or constitutional conditions and that tend to recurrences and inveteracy. Eczema may appear on any part of the body, but in horses it is especially common on the heels and the lower parts of the limbs, and less frequently on the neck, shoulder, and abdomen. The limbs appear to be especially liable because of their dependent position, all blood having to return from them against the action of gravity and congestions and swellings being common, because of the abundance of blood vessels in this part of the skin and because of the frequent contact with the irritant dung and urine and their ammoniacal emanations. The legs further suffer from contact with wet and mud when at work, from snow and ice, from drafts of cold air on the wet limbs, from washing with caustic soaps, or from the relaxing effects of a too deep and abundant litter. Among other causes may be named indigestion and the presence of irritant matters in the blood and sweat, the result of patent medicated feeds and condition powders (aromatics, stimulants), green food, new hay, new oats, buckwheat, wheat, maize, diseased potatoes, smut, or ergot in grains, decomposing green feed, brewers' grains, or kitchen garbage. The excitement in the skin, caused by shedding the coat, lack of grooming, hot weather, hot, boiled, or steamed feed conduces to the eruption. Lastly, any sudden change of feed may induce it.

The blisters may in part go on to suppuration so that vesicles and pustules often appear on the same patch, and, when raw from rubbing, the true nature of the eruption may be completely masked. In well-fed horses, kept in close stables with little work, eczema of the limbs may last for months and years. It is a very troublesome affection in draft stallions.

Treatment.—This disease is so often the result of indigestion that a laxative of 1 pound Glauber's salt in 3 or 4 quarts water or 1-1/2 pints olive oil is often demanded to clear away irritants from the alimentary canal. Following this, in recent and acute cases, give 2 drams of acetate or bicarbonate of potash twice a day in the drinking water. If the bowels still become costive, give daily 1 ounce sulphate of soda and 20 grains of powdered nux vomica. In debilitated horses combine the nux vomica with one-half ounce powdered gentian root. As a wash for the skin use 1 dram bicarbonate of soda and 1 dram carbolic acid in a quart of water, after having cleansed the surface with tepid water. Employ the same precautions as regards feeding, stabling, and care of harness as in simple congestion of the skin.

In the more inveterate forms of eczema more active treatment is required. Soak the scabs in fresh sweet oil, and in a few hours remove these with tepid water and Castile soap; then apply an ointment of sulphur or iodid of sulphur day by day. If this seems to be losing its effect after a week, change for mercurial ointment or a solution of sulphid of potassium, or of hyposulphite of soda, 3 drams to the quart of water. In these cases the animal may take a course of sulphur (1 ounce daily), bisulphite of soda (one-half ounce daily), or of arsenic (5 grains daily) mixed with 1 dram bicarbonate of soda.

INFLAMMATION WITH PUSTULES.

In this affection the individual elevations on the inflamed skin show in the center a small sac of white, creamy pus, in place of the clear liquid of a blister. They vary in size from a millet seed to a hazelnut. The pustules of glanders (farcy buds) are to be distinguished by the watery contents and the cordlike swelling, extending from the pustules along the line of the veins, and those of boils by the inflammation and sloughing out of a core of the true skin. The hair on the pustule stands erect, and is often shed with the scab which results. When itching is severe the parts become excoriated by rubbing, and, as in the other forms of skin disease, the character of the eruption may become indistinct. Old horses suffer mainly at the root of the mane and tail and about the heels, and suckling foals around the mouth, on the face, inside the thighs, and under the tail.

Pustules, like eczema, are especially liable to result from unwholesome feed and indigestion, from a sudden change of feed—above all, from dry to green. In foals it may result from overheating of the mare and allowing the first milk after she returns, or by milk rendered unwholesome by faulty feeding of the dam. If a foal is brought up by hand the souring and other decompositions in the milk derange the digestion and cause such eruption. Vetches and other plants affected with honeydew and buckwheat have been the cause of these eruptions on white portions of the skin. Disorders of the kidneys or liver are common causes of this affection.

Treatment.—Apply soothing ointments, such as benzonated oxid of zinc, or vaseline with 1 dram oxid of zinc in each ounce. Or a wash of 1 dram sugar of lead or 2 drams hyposulphite of soda in a quart of water may be freely applied. If the skin is already abraded and scabby, smear thickly with vaseline for some hours, then wash with soapsuds and apply the above dressings. When the excoriations are indolent they may be painted with a solution of lunar caustic 2 grains to 1 ounce of distilled water. Internally counteract costiveness and remove intestinal irritants by the same means as in eczema, and follow this with one-half ounce doses daily of hyposulphite of soda, and one-half ounce doses of gentian. Inveterate cases may often be benefited by a course of sulphur, bisulphite of soda, or arsenic. In all, the greatest care must be taken with regard to feed, feeding, watering, cleanliness, and work. In wet and cold seasons predisposed animals should, so far as possible, be protected from wet, mud, snow, and melted snow—above all, from that which has been melted by salt.

BOILS, OR FURUNCLES.

These may appear on any part of the skin, but are especially common on the lower parts of the limbs, and on the shoulders and back where the skin is irritated by accumulated secretion and chafing with the harness. In other cases the cause is constitutional, or attended with unwholesome diet and overwork with loss of general health and condition. They also follow on weakening diseases, notably strangles, in which irritants are retained in the system from overproduction of poisons and effete matter during fever, and imperfect elimination. There is also the presence of a pyogenic bacterium, by which the disease may be maintained and propagated.

While boils are pus producing, they differ from simple pustule in affecting the deepest layers of the true skin, and even the superficial layers of the connective tissues beneath, and in the death and sloughing out of the central part of the inflamed mass (core). The depth of the hard, indurated, painful swelling, and the formation of this central mass or core, which is bathed in pus and slowly separated from surrounding parts, serve to distinguish the boil alike from the pustule, from the farcy bud, and from a superficial abscess.

Treatment.—To treat very painful boils a free incision with a lancet in two directions, followed by a dressing with one-half an ounce carbolic acid in a pint of water, bound on with cotton wool or lint, may cut them short. The more common course is to apply a warm poultice of linseed meal or wheat bran, and renew daily until the center of the boil softens, when it should be lanced and the core pressed out.

If the boil is smeared with a blistering ointment of Spanish flies and a poultice put over it, the formation of matter and separation of the core is often hastened. A mixture of sugar and soap laid on the boil is equally good. Cleanliness of the skin and the avoidance of all causes of irritation are important items, and a teaspoonful of bicarbonate of soda once or twice a day will sometimes assist in warding off a new crop.

NETTLERASH (SURFEIT, OR URTICARIA).

This is an eruption in the form of cutaneous nodules, in size from a hazelnut to a hickory nut, transient, with little disposition to the formation of either blister or pustule, and usually connected with shedding of the coat, sudden changes of weather, and unwholesomeness or sudden change in the feed. It is most frequent in the spring and in young and vigorous animals (good feeders). The swelling embraces the entire thickness of the skin and terminates by an abrupt margin in place of shading off into surrounding parts. When the individual swellings run together there are formed extensive patches of thickened integument. These may appear on any part of the body, and may be general; the eyelids may be closed, the lips rendered immovable, or the nostrils so thickened that breathing becomes difficult and snuffling. It may be attended with constipation or diarrhea or by colicky pains. The eruption is sudden, the whole skin being sometimes covered in a few hours, and it may disappear with equal rapidity or persist for six or eight days.

Treatment.—This consists in clearing out the bowels by 5 drams Barbados aloes, or 1 pound Glauber's salt, and follow the operation of these by daily doses of one-half ounce powdered gentian and 1 ounce Glauber's salt. A weak solution of alum may be applied to the swellings.

PITYRIASIS, OR SCALY SKIN DISEASE.

This affection is characterized by an excessive production and detachment of dry scales from the surface of the skin (dandruff). It is usually dependent on some fault in digestion and an imperfect secretion from the sebaceous glands and is most common in old horses with spare habit of body. Williams attributes it to feed rich in saccharine matter (carrots, turnips) and to the excretion of oxalic acid by the skin. He has found it in horses irregularly worked and well fed and advises the administration of pitch for a length of time and the avoidance of saccharine feed. Otherwise the horse may take a laxative followed by dram doses of carbonate of potash, and the affected parts may be bathed with soft, tepid water and smeared with an ointment made with vaseline and sulphur. In obstinate cases sulphur may be given daily in the feed.

PRURITUS, OR NERVOUS IRRITATION OF THE SKIN.

This is seen in horses fed to excess on grain and hay, kept in close stables, and worked irregularly. Though most common in summer, it is often severe in hot, close stables in winter. Pimples, vesicles, and abrasions may result, but as the itching is quite as severe on other parts of the skin, these may be the result of scratching merely. It is especially common and inveterate about the roots of the mane and tail.

Treatment consists in a purgative (Glauber's salt, 1 pound), restricted, laxative diet, and a wash of water slightly soured with oil of vitriol and rendered sweet by carbolic acid. If obstinate, give daily 1 ounce of sulphur and 20 grains nux vomica. If the acid lotion fails, 2 drams carbonate of potash and 2 grains of cyanid of potassium in a quart of water will sometimes benefit. If from pinworms in the rectum, the itching of the tail may be remedied by an occasional injection of a quart of water in which chips of quassia wood have been steeped for 12 hours.

HERPES.

This name has been applied to a disease in which there is an eruption of minute vesicles in circular groups or clusters, with little tendency to burst, but rather to dry up into fine scabs. If the vesicles break, they exude a slight, gummy discharge which concretes into a small, hard scab. It is apparently noncontagious and not appreciably connected with any disorder of internal organs. It sometimes accompanies or follows specific fevers, and is, on the whole, most frequent at the seasons of changing the coat—spring and autumn. It is seen on the lips and pastern, but may appear on any part of the body. The duration of the eruption is two weeks or even more, the tendency being to spontaneous recovery. The affected part is very irritable, causing a sensitiveness and a disposition to rub out of proportion to the extent of the eruption.

Treatment.—It may be treated by oxid of zinc ointment, and to relieve the irritation a solution of opium or belladonna in water, or of sugar of lead or oil of peppermint. A course of bitters (one-half an ounce of Peruvian bark daily for a week) may be serviceable in bracing the system and producing an indisposition to the eruption.

BLEEDING SKIN ERUPTIONS, OR DERMATORRHAGIA PARASITICA.

In China, Hungary, Spain, and other countries horses frequently suffer from the presence of a threadworm (Filaria haemorrhagica Railliet, F. multipapillosa Condamine and Drouilly) in the subcutaneous connective tissue, causing effusions of blood under the scurf skin and incrustations of dried blood on the surface. The eruptions, which appear mainly on the sides of the trunk, but may cover any part of the body, are rounded elevations about the size of a small pea, containing blood which bursts through the scurf skin and concretes like a reddish scab around the erect, rigid hairs. These swellings appear in groups, which remain out for several days, gradually diminishing in size; new groups appear after an interval of three or four weeks, the manifestation being confined to three or four months of spring and disappearing in winter. A horse will suffer for several years in succession and then permanently recover. A fatal issue is not unknown. To find the worm the hair is shaved from the part where the elevations are felt, and as soon as a bleeding point is shown the superficial layer is laid open with the knife, when the parasite will be seen drawing itself back into the parts beneath. The worm is about 2 inches long and like a stout thread, thicker toward the head than toward the tail, and with numerous little conical elevations (papillae) around the head. The young worms are numerous in the body of the adult female worm. The worm has become common in given localities, and probably enters the system with feed or water.

Treatment is not satisfactory, but the affected surface should be kept clean by sponging, and the pressure of harness on any affected part must be avoided. Thus rest may become essential. The part may be frequently washed with a strong solution of potassium sulphid.

SUMMER SORES FROM FILARIA IRRITANS.

The summer sores of horses (dermatitis granulosa, boils) have been traced to the presence in the skin of another parasite, 3 millimeters in length and extremely attenuated (Filaria irritans Railliet). The sores may be seen as small as a millet seed, but more frequently the size of a pea, and may become an inch in diameter. They may appear on any point, but are especially obnoxious where the harness presses or on the lower parts of the limbs. They cause intense and insupportable itching, and the victim rubs and bites the part until extensive raw surfaces are produced. Aside from such friction the sore is covered by a brownish-red, soft, pulpy material with cracks or furrows filled with serous pus. In the midst of the softened mass are small, firm, rounded granulations, fibrinous, and even caseated, and when the soft, pultaceous material has been scraped off, the surface bears a resemblance to the fine, yellow points of miliary tuberculosis in the lung. The worm or its debris is found in the center of such masses. These sores are very obstinate, resisting treatment for months in summer, and even after apparent recovery during the cold season they may appear anew the following summer. In bad cases the rubbing and biting may cause exposure of synovial sacs and tendons, and cause irremediable injury. Even in winter, however, when the diseased process seems arrested, there remain the hard, firm, resistant patches of the skin with points in which the diseased product has become softened like cheese.

The apparent subsidence of the disease in winter is attributed to the coldness and comparative bloodlessness of the skin, whereas in summer, with high temperature, active circulation, and rapid cell growth, inflammation is increased, itching follows, and from the animal rubbing the part the irritation is persistently increased. The hotter the climate the more troublesome the disease.[4]

Treatment consists, first, in placing the animal in a cool place and showering the surface with cold water. The parasite may be destroyed by rubbing the surface of the wound with iodoform and covering it with a layer of collodion, and repeating the applications very 24 hours for 15 days, or until the sores heal up. Ether or chloroform, poured on cotton wool and applied to the sore for two minutes before painting it with collodion, may be used in place of iodoform.[5]

CRACKED HEELS (SCRATCHES, OR CHAPS ON KNEE AND HOCK).

This usually sets in with swelling, heat, and tenderness of the hollow of the heel, with erections of the hairs and redness (in white skins), with stiffness and lameness, which may be extreme in irritable horses. Soon slight cracks appear transversely, and may gain in depth and width, and may even suppurate. More frequently they become covered at the edges or throughout by firm incrustations resulting from the drying of the liquids thrown out, and the skin becomes increasingly thick and rigid. A similar condition occurs behind the knee and in front of the hock (malanders and salanders), and may extend from these points to the hoof, virtually incasing that side of the limb in a permanent incrusting sheath.

Causes.—Besides a heavy lymphatic constitution, which predisposes to this affection, the causes are overfeeding on grain, unwholesome fodder, close, hot, dirty stables, constant contact with dung and urine and their emanations, working in deep, irritant mud; above all, in limestone districts, irritation by dry limestones or sandy dust in dry weather on dirt roads; also cold drafts, snow, and freezing mud, washing the legs with caustic soap, wrapping the wet legs in thick woolen bandages which soak the skin and render it sensitive when exposed next day, clipping the heels, weak heart and circulation, natural or supervening on overwork, imperfect nourishment, impure air, lack of sunshine, chronic exhausting, or debilitating diseases, or functional or structural diseases of the heart, liver, or kidneys. These last induce dropsical swelling of the limbs (stocking), weaken the parts, and induce cracking. Finally the cicatrix of a preexisting crack, weak, rigid, and unyielding, is liable to reopen under any severe exertion; hence rapid paces and heavy draft are active causes.

Treatment.—In treatment the first step is to ascertain and remove the cause whenever possible. If there is much local heat and inflammation, a laxative (5 drams aloes or 1 pound Glauber's salt) may be given, and for the pampered animal the grain should be reduced or replaced altogether by bran mashes, flaxseed, and other laxative, nonstimulating feed. In the debilitated, on the other hand, nutritious food and bitter tonics may be given, and even a course of arsenic (5 grains arsenic with 1 dram bicarbonate of soda daily). When the legs swell, exercise on dry roads, hand rubbing, and evenly applied bandages are good, and mild astringents, like extract of witch-hazel, may be applied and the part subsequently rubbed dry and bandaged. If there is much heat but unbroken skin, a lotion of 2 drams sugar of lead to 1 quart of water may be applied on a thin bandage, covered in cold weather with a dry one. The same may be used after the cracks appear, or a solution of sulphurous acid 1 part, glycerin 1 part, and water 1 part, applied on cotton and well covered by a bandage. In case these should prove unsuitable to the particular case, the part may be smeared with vaseline 1 ounce, sugar of lead 1 dram, and carbolic acid 10 drops.

INFLAMMATION OF THE HEELS WITH SEBACEOUS SECRETION (GREASE, OR CANKER).

This is a specific affection of the heels of horses usually associated with the growth of a parasitic fungus, an offensive discharge from the numerous sebaceous glands, and, in bad cases, the formation of red, raw excrescences (grapes) from the surface. It is to be distinguished (1) from simple inflammation in which the special fetid discharge and the tendency to the formation of "grapes" are absent; (2) from horsepox, in which the abundant exudate forms a firm, yellow incrustation around the roots of the hair, and is embedded at intervals in the pits formed by the individual pocks, and in which there is no vascular excrescence; (3) from foot scabies (mange), in which the presence of an acarus is distinctive; (4) from lymphangitis, in which the swelling appears suddenly, extending around the entire limb as high as the hock, and on the inner side of the thigh along the line of the vein to the groin, and in which there is active fever, and (5) from erysipelas, in which there is active fever (wanting in grease), the implication of the deeper layers of the skin and of the parts beneath giving a boggy feeling to the parts, the absence of the fetid, greasy discharge, and finally a tendency to form pus loosely in the tissues without any limiting membrane, as in abscess. Another distinctive feature of grease is its tendency to implicate the skin which secretes the bulbs or heels of the horny frog and in the cleft of the frog, constituting the disease known as canker.

Causes.—The predisposing causes of grease are essentially the same as those of simple inflammation of the heel, so that the reader may consult the preceding section. Though a specific fungus and bacteria of different kinds are present, they tend mainly to aggravation of the disease, and are not proved to be essential factors in causation.

Symptoms.—The symptoms vary according to whether the disease comes on suddenly or more tardily. In the first case there is a sudden swelling of the skin in the heel, with heat, tenderness, itching, and stiffness, which is lessened during exercise. In the slower forms there is seen only a slight swelling after rest, and with little heat or inflammation for a week or more. Even at this early stage, a slight, serous oozing may be detected. As the swelling increases, extending up toward the hock or knees, the hairs stand erect, and are bedewed by moisture no longer clear and odorless, but grayish, milky, and fetid. The fetor of the discharge draws attention to the part whenever one enters the stable, and the swollen pastern and wet, matted hairs on the heel draw attention to the seat of the malady. If actively treated, the disease may not advance further, but if neglected the tense, tender skin cracks open, leaving open sores from which vascular bleeding growths grow up, constituting the "grapes." The hair is shed, and the heel may appear but as one mass of rounded, red, angry excrescences which bleed on handling and are covered with the now repulsively fetid, decomposing discharge. During this time there is little or no fever, the animal feeds well, and but for its local trouble it might continue at work. When the malady extends to the frog, there is a fetid discharge from its cleft or from the depressions at its sides, and this gradually extends to its whole surface and upon the adjacent parts of the sole. The horn meanwhile becomes soft, whitish, and fleshy in aspect, its constituent tubes being greatly enlarged and losing their natural cohesion; it grows rapidly above the level of the surrounding horn, and when pared is found to be penetrated to an unusual depth by the secreting papillae, and that at intervals these have bulged out into a vascular fungous mass comparable to the "grapes."

Treatment.—In treatment hygienic measures occupy a front rank, but are in themselves insufficient to establish a cure. All local and general conditions which favor the production and persistence of the disease must be guarded against. Above all, cleanliness and purity of the stable and air must be obtained; also nourishing diet, regular exercise, and the avoidance of local irritants—septic, muddy, chilling, etc. At the outset benzoated oxid of zinc ointment may be used with advantage. A still better dressing is made with 1 ounce vaseline, 2 drams oxid of zinc, and 20 drops iodized phenol. If the surface is much swollen and tender, a flaxseed poultice may be applied, over the surface of which has been poured some of the following lotion: Sugar of lead, one-half ounce; carbolic acid, 1 dram; water, 1 quart. All the astringents of the pharmacopoeia have been employed with more or less advantage, and some particular one seems to suit particular cases or patients. To destroy the grapes, they may be rubbed daily with strong caustics (copperas, bluestone, lunar caustic), or each may be tied round its neck with a stout, waxed thread, or, finally and more speedily, they may be cut off by a black-smith's shovel heated to redness and applied with its sharp edge toward the neck of the excrescence, over a cold shovel held between it and the skin to protect the skin from the heat. The cold shovel must be kept cool by frequent dipping in water. After the removal of the grapes the astringent dressing must be persistently applied to the surface. When the frog is affected, it must be pared to the quick and dressed with dry caustic powders (quicklime, copperas, bluestone) or carbolic acid and subjected to pressure, the dressing being renewed every day at least.

ERYSIPELAS.

This is a specific contagious disease, characterized by spreading, dropsical inflammation of the skin and subcutaneous tissues, attended with general fever. It differs from most specific diseases in the absence of a definite period of incubation, a regular course and duration, and a conferring of immunity on the subject after recovery. On the contrary, one attack of erysipelas predisposes to another, partly, doubtless, by the loss of tone and vitality in the affected tissues, but also, perhaps, because of the survival of the infecting germ.

Cause.—It is no longer to be doubted that the microbes found in the inflammatory product are the true cause of erysipelas, as by their means the disease can be successfully transferred from man to animals and from one animal to another. This transition may be direct or through the medium of infected buildings or other articles. Yet from the varying severity of erysipelas in different outbreaks and localities it has been surmised that various different microbes are operative in this disease, and a perfect knowledge of them might perhaps enable us to divide erysipelas into two or more distinct affections. At present we must recognize it as a specific inflammation due to a bacterial poison and closely allied to septicemia. Erysipelas was formerly known as surgical when it spread from a wound (through which the germ had gained access) and medical, or idiopathic, when it started independently of any recognizable lesion. Depending as it does, however, upon a germ distinct from the body, the disease must be looked upon as such, no matter by what channel the germ found an entrance. Erysipelas which follows a wound is usually much more violent than the other form, the difference being doubtless partly due to the lowered vitality of the wounded tissues and to the oxidation and septic changes which are invited on the raw, exposed surface. As apparently idiopathic cases may be due to infection through bites of insects, the small amount of poison inserted may serve to moderate the violence.

This affection may attack a wound on any part of the horse's body, while, apart from wounds, it is most frequent about the head and the hind limbs. It is to be distinguished from ordinary inflammations by its gradual extension from the point first attacked, by the abundant liquid exudation into the affected part, by the tension of the skin over the affected part, by its soft, boggy feeling, allowing it to be deeply indented by the finger, by the abrupt line of limitation between the diseased and the healthy skin, the former descending suddenly to the healthy level instead of shading off slowly toward it, by the tendency of the inflammation to extend deeply into the subjacent tissues and into the muscles and other structures, by the great tendency to death and sloughing of portions of skin and of the structures beneath, by the formation of pus at various different points throughout the diseased parts without any surrounding sac to protect the surrounding structures from its destructive action, and without the usual disposition of pus to advance harmlessly toward the surface and escape; and, finally, by a low, prostrating type of fever, with elevated temperature of the body, coated tongue, excited breathing, and loss of appetite. The pus when escaping through a lancet wound is grayish, brownish, or reddish, with a heavy or fetid odor, and inter-mixed with shreds of broken-down tissues. The most destructive form, however, is that in which pus is deficient and gangrene and sloughing more speedy and extensive.

Treatment resolves itself mainly into the elimination from the system of the poisonous products of the bacteria by laxatives and diuretics, the sustaining of the failing vitality by tonics and stimulants, above all those of the nature of antiferments, and the local application of astringent and antiseptic agents. Internal treatment may consist in 4 drams tincture of muriate of iron and one-half dram muriate of ammonia or chlorate of potash, given in a pint of water every two hours. To this may be added, liberally, whisky or brandy when the prostration is very marked. Locally a strong solution of iron, alum, or of sulphate of iron and laudanum may be used; or the affected part may be painted with tincture of muriate of iron or with iodized phenol. In mild cases a lotion of 4 drams sugar of lead and 2 ounces laudanum in a quart of water may be applied. It is desirable to avoid the formation of wounds and the consequent septic action, yet when pus has formed and is felt by fluctuation under the finger to be approaching the surface it should be freely opened with a clean, sharp lancet, and the wound thereafter disinfected daily with carbolic acid 1 part to water 10 parts, with a saturated solution of hyposulphite of soda, or with powders of iodoform or salol.

HORSEPOX, ANTHRAX, AND CUTANEOUS GLANDERS (FARCY).

These subjects are discussed under the head of contagious diseases.

CALLOSITIES.

These are simple thickening and induration of the cuticle by reason of continued pressure, notably in lying down on a hard surface. Being devoid of hair, they cause blemishes; hence, smooth floors and good bedding should be provided as preventives.

HORNY SLOUGHS (SITFASTS), OR SLOUGHING CALLOSITIES.

These are circumscribed sloughs of limited portions of the skin, the result of pressure by badly fitting harness or by irritating masses of dirt, sweat, and hairs under the harness. They are most common under the saddle, but may be found under collar or breeching as well. The sitfast is a piece of dead tissue which would be thrown off but that it has formed firm connections with the fibrous skin beneath, or even deeper with the fibrous layers (fascia) of the muscles, or with the bones, and is thus bound in its place as a persistent source of irritation. The hornlike slough may thus involve the superficial part of the skin only, or the whole thickness of the skin, and even of some of the structures beneath. The first object is to remove the dead irritant by dissecting it off with a sharp knife, after which the sore may be treated with simple wet cloths or a weak carbolic-acid lotion, like a common wound. If the outline of the dead mass is too indefinite, a linseed-meal poultice will make its outline more evident to the operator. If the fascia or bone has become gangrenous, the dead portion must be removed with the hornlike skin. During and after treatment the horse must be kept at rest or the harness must be so adjusted that no pressure can come near the affected parts. (See also page 496.)