Since the introduction of the mallein test it is not of so much importance as it formerly was to estimate the value of certain indications which were once looked upon as sufficient to render an animal suspected. The distinctive symptoms of the worst stage of glanders are not easily mistaken; in fact, they are quite familiar to most persons who have been in any way concerned with the management of horses. Ulceration of the lining membrane of the nostrils, with an adhesive discharge at first of semi-transparent character and later of a purulent nature, with swelling of the glands under the jaw, are among the most characteristic symptoms. The local disease of the nasal membrane is commonly confined to one side, so far at least as clinical examination can determine, and the enlarged glands are always on the side corresponding to the diseased nostril. In the chronic form of glanders the discharge from the nostril is sometimes so slight as to attract very little attention, and no ulcers can be seen on any part of the nasal membrane, which, however, is frequently pallid or of a bluish discoloration. Even these symptoms are, however, absent in many cases in which a post-mortem examination will prove the animal to be affected with glanders.
When glanders presents itself in the form of farcy, the real difference in the symptoms results from the presence of the local disease in the skin, chiefly that of the hind extremities. The nodules and subsequent ulceration in the mucous membrane, which are characteristic of glanders, are accepted as indications of farcy when they appear in the skin. In both forms of the disease there is the same affection of the lymphatic vessels and their associated glands, and the distinctive nodules of glanders which are found in the lungs are also seen in cases of farcy.
Accompanying the eruption of the so-called farcy buds in the skin of the extremities there is usually a tumefaction of the lymphatic vessels and general enlargement of the affected limb. Indeed, the first symptom of the disease is commonly a certain degree of stiffness of movement, which becomes more marked as the swelling increases. Farcy, when treated as a separate disease, was considered to be less serious and more amenable to treatment than glanders. In many instances animals apparently recovered under a course of tonic medicine with liberal rations, but it was allowed that such recovered animals often exhibited distinctive symptoms of glanders after an attack of any acute disease, as influenza or pneumonia.
The symptoms of farcy are so definite that any experienced stableman would consider himself competent to decide whether or not the disease existed in any horse under his charge, but recent investigations by Algerian veterinary surgeons, and also by Professor Nocard, indicate that it is extremely likely for the most marked symptoms to lead to a wrong diagnosis, as there exists in horses a form of inflammation of the lymphatics - which was first noticed by the veterinary surgeons of the Algerian army, and described by them as suppurating lymphangitis - which presents the chief symptoms of farcy, i.e. swelling of the limb, enlargement of the lymph vessels, formation of small tumours (farcy buds) which burst and subsequently undergo ulceration.
How extremely close the resemblance between the two diseases - epizootic lymphangitis and farcy - is may be judged from Professor Nocard's remarks in reference to fifty-nine cases of apparent farcy - forty-three only were really the subjects of the true disease (glanders); the other sixteen were affected with suppurating lymphangitis. The two affections may be distinguished by microscopic examination of the matter discharged from the pustules in the skin. In epizootic lymphangitis will be observed a number of small, highly retractile lemon-shaped bodies, some free and others contained in the pus corpuscles. These are the cryptococci by which the disease is caused. Glanders, on the other hand, will be recognized by the mallein test, and, in addition, the inoculation of guinea-pigs and the cultivation of the organism on different media, as potato, bouillon, agar-agar, and serum-gelatine. Such complicated tests are, of course, not likely to be applied excepting in cases where a valuable horse is condemned as suffering from farcy, and the symptoms are limited to the lymphatics of the extremities.