The epizootic diseases affecting the horse are not numerous, and
may generally be considered as specific and infectious or contagious
Epizootic and contagious diseases.
in their nature, circumstances of a favourable kind leading
to their extension by propagation of the agent upon which
their existence depends. This agent, in most of the
maladies, has been proved to be a micro-organism, and
there can be little doubt that it is so for all of them.
Glanders (q.v.), or equinia, one of the most serious maladies of the horse, ass and mule, prevails in nearly every part of the world. Glanders: farcy. It is a contagious, inoculable disease, caused by the bacillus mallei, and specially affects the lungs, respiratory mucous membrane and the lymphatic system. The virulent agent of glanders appears to establish itself most easily among horses kept in foul, crowded, badly ventilated stables, or among such as are over-worked, badly fed or debilitated. Glanders, however, is always due to contagion, and in natural infection it may be contracted by inhalation of the bacilli, by ingestion of the virus with food or water, or by inoculation of a wound of the skin or a mucous membrane. Carnivorous animals—lions, tigers, dogs and cats—have become infected through eating the flesh of glandered horses; and men attending diseased horses are liable to be infected, especially if they have sores on the exposed parts of their bodies. Though in man infection through wounds is the readiest way of receiving the disease, the bacillus may also obtain access through the digestive organs, the lungs and mucous membranes of the eyes, nose and lips.
In descriptions of the equine disease sometimes a distinction is made between glanders with nasal ulcers and other symptoms of respiratory disease, and glanders of the skin, or farcy, but there is no essential difference between them. Glanders and farcy are due to the same causal organism, and both may be acute or chronic. Acute glanders is always rapidly fatal, and chronic glanders may become acute or it may terminate by apparent recovery.
The symptoms of acute glanders are initial fever with its accompaniments, thirst, loss of appetite, hurried pulse and respiration, emaciation, languor and disinclination to move. Sometimes the legs or joints are swollen and the horse is stiff; but the characteristic symptoms are a greyish-yellow viscid discharge from one or both nostrils, a peculiar enlarged and nodulated condition of one or both submaxillary lymphatic glands, which though they may be painful very rarely suppurate, and on the nasal membrane small yellow pimples or pustules, running into deep, ragged-edged ulcers, and sometimes on the septum large patches of deep ulceration. The discharge from the nose adheres to the nostrils and upper lip, and the infiltrated nasal lining, impeding breathing, causes snuffling and frequent snorting. The lymphatic vessels of the face are often involved and appear as painful subcutaneous “cords” passing across the cheek. These vessels sometimes present nodules which break and discharge a glutinous pus. As the disease progresses, the ulcers on the nose increase in number, enlarge or become confluent, extend in depth and sometimes completely perforate the septum. The nasal discharge, now more abundant and tenacious, is streaked with blood and offensive, the respiration is noisy or roaring, and there may be coughing with bleeding from the nose. Painful oedematous swellings appear on the muzzle, throat, between the fore legs, at the flank or on the limbs, and “farcy buds” may form on some of the swollen parts. Symptoms of congestion of the lungs, or pneumonia and pleurisy, with extreme prostration, diarrhoea and gasping respiration, precede death, which is due to asphyxia or to exhaustion.
Chronic or latent glanders generally presents few definite symptoms. The suspected animal may have a discharge from the nose, or an enlarged submaxillary gland, or both, and small unbroken nodules may exist on the septum, but usually there is no visible ulceration of the nasal membrane. In some horses suspicion of glanders may be excited by lameness and sudden swelling of a joint, by profuse staling, sluggishness, loss of condition and general unthriftiness, or by refusal of food, rise of temperature, swollen fetlocks, with dry hacking cough, nasal catarrh and other symptoms of a common cold. With rest in the stable the horse improves, but a one-sided nasal discharge continues, the submaxillary gland enlarges, and, after an interval, ulcers appear in the nose or “farcy buds” form on a swollen leg. In occult glanders the horse may appear to be in good health and be able to perform ordinary work. In these cases the existence of glanders can only be discovered by resorting to inoculation or the malleia test.
In cutaneous glanders, or farcy, symptoms occur on the skin of a limb, usually a hind one, or on the body, where the lymphatics become inflamed and ulcerated. The limb is much swollen, and the animal moves with pain and difficulty. The lymphatic vessels appear as prominent lines or “cords,” hard and painful on manipulation, and along their course arise nodular swellings—the so-called “farcy buds.” These small abscesses break and discharge a yellow, glutinous, blood-stained pus, leaving sores which heal very slowly. There is a rise of temperature with other symptoms of constitutional disturbance.
Medical treatment of glanders or farcy should not be attempted. The disease is dealt with under the Contagious Diseases (Animals) Acts. Horses which present suspicious symptoms, or those which have been in contact, or have stood in the same stable with glandered horses, should be isolated and tested with mallein. Animals which are found affected should immediately be destroyed, and their harness, clothing and the utensils employed with them thoroughly cleansed, while the stalls, horse-boxes and places which the horses have frequented should be disinfected. Forage left by glandered horses should be burned or fed to cattle.
Mallein, which is almost indispensable in the diagnosis of latent glanders, was discovered in 1888 by Helman, a Russian military veterinary surgeon, and the first complete demonstration of its diagnostic value was given in 1891 by Kalning, also of Russia. Mallein, prepared for the diagnosis of glanders in animals, is the sterilized and filtered liquid-culture of glanders bacilli. It therefore does not contain even dead bacilli, but it has in solution certain substances which are added to the liquid by the bacilli during their growth (McFadyean). Employed under proper precautions and subcutaneously injected in a glandered horse, mallein causes a marked rise of temperature and an extensive painful swelling at the seat of injection.
Epizootic lymphangitis is a contagious eruptive disease of the horse caused by the cryptococcus farciminosus, and characterized Epizootic lymphangitis. by nodular swellings and suppuration of the superficial lymphatics. Infection can be transmitted by mediate or immediate contagion. The eruption usually appears on the limbs, but it may occur on the body or on the head and neck. The symptoms closely resemble those of cutaneous glanders or farcy, from which this disease may readily be distinguished by microscopic examination of the pus discharged from the sores, or by testing the horse with mallein. Glanders and epizootic lymphangitis may coexist in the same animal. It is a scheduled disease, and treatment should not be attempted.
Strangles is a specific contagious eruptive fever peculiar to horses, and is more especially incidental to young animals. It is particularly Strangles. characterized by the formation of abscesses in the lymphatic glands, chiefly those between the branches of the lower jaw (submaxillary). Various causes have been ascribed for its production, such as change of young horses from field to stable, from to dry feeding, from idleness to hard work, irritation of teething, and change of locality and climate. But the sole cause is infection by the strangles streptococcus. Languor and feverishness, diminution of appetite, cough, redness of the nasal membrane, with discharge from the eyes and nose, and thirst are among the earliest symptoms. Then there is difficulty in swallowing, coincident with the development of swelling between the branches of the lower jaw, which often causes the water in drinking to be returned through the nose and the masticated food to be dropped from the mouth. The swelling is hot and tender, diffused, and uniformly rounded and smooth; at first it is hard, with soft, doughy margins; but later it becomes soft in the centre, where an abscess is forming, and soon “points” and bursts, giving exit to a quantity of pus. Relief is now experienced by the animal; the symptoms subside, and recovery takes place. In some cases the swelling is so great or occurs so close to the larynx that the breathing is interfered with, and even rendered so difficult that suffocation is threatened. In other cases the disease assumes an irregular form, and the swelling, instead of softening in the centre, remains hard for an indefinite time, or it may subside and abscesses form in various parts of the body, sometimes in vital organs, as the brain, lungs, liver, kidneys, &c., or in the bronchial or mesenteric glands, where they generally produce serious consequences. Not unfrequently a pustular eruption accompanies the other symptoms. The malady may terminate in ten days or be protracted for months, sometimes terminating fatally from complications, even when the animal is well nursed a kept in a healthy stable.
Good nursing is the chief part of the treatment. The strength should be maintained by soft nutritious food, and the body kept warm and comfortable; the stable or loose-box must have plenty of fresh air and be kept clean. The swelling may be fomented with warm water or poulticed. The poultice may be a little bag containing bran and linseed meal mixed with hot water and applied warm to the tumefaction, being retained there by a square piece of calico, with holes for the ears and eyes, tied down the middle of the face and behind the ears. If the breathing is disturbed and noisy, the animal may be made to inhale steam from hot water in a bucket or from bran mash. If the breathing becomes very difficult, the windpipe must be opened and a tube inserted. Instead of the swelling being poulticed, a little blistering ointment is sometimes rubbed over it, which hastens pointing of the abscess. When the abscess points, it may be lanced, though sometimes it is better to allow it to break spontaneously.
It is important to distinguish strangles from glanders, and the distinction can, with certainty, be ascertained by resorting to the mallein test for glanders, or by microscopical examination of the pus from the strangles abscess.
Under influenza several diseases are sometimes included, and in different invasions it may (and doubtless does) assume varying Influenza. forms. It is a specific fever of a low or asthenic type, associated with inflammation of the mucous membrane lining the air-passages, and also sometimes with that of
