Chapter 55

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, bullæ) 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 hæmorrhagica_ 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 (papillæ) 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 débris 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).