SYMPTOMS.—Acute nasal glanders in horses has a period of incubation lasting from three to five days in inoculated cases. Where in infected subjects the incubation appears to have extended over months or a year, there have usually (or always) been deposits in internal organs which passed without recognition until the lesions appeared in the nose. At the outset there is fever, which appears before any local lesions are recognizable, even post-mortem (Chauveau), and soon with languor, and loss of appetite, there is a serous nasal discharge, often from one side only. By the sixth day this has become yellowish, the margin of the nostril is often swollen, and upon the pituitary membrane may be detected elevations of various sizes of a general yellowish tinge, dotted with minute red points and surrounded by a bright-red or purple and slightly elevated areola. These may be simple, pea-like nodules or more or less extensive patches, which in certain cases extend over nearly the whole pituitary membrane. At the same time the submaxillary lymphatic glands on the same side become the seat of a hard nodular painless enlargement, feeling like a conglomerate mass of peas, and often showing a tendency to become more closely adherent to some adjacent part (bone, skin, base of tongue); but they only ulcerate exceptionally. Extensive hot, painful engorgements also often appear on other parts of the body, and if on the limbs or joints cause lameness. Soon the swellings on the mucosa become eroded and are gradually destroyed, forming large unhealthy, chancrous-looking ulcers, tending to become confluent and to eat deeply through the mucosa into the subjacent tissues. These are mostly reddish gray or yellowish gray, with raised ragged red or yellowish-red margins. They bleed readily, and may be black from hemorrhage, or greenish or of some other shade from decomposition. The discharge is always somewhat glutinous and sticky, but it may vary in color from simple white to yellowish, greenish, brownish, or red, according to the destruction of tissue, the septic changes, or the effusion of blood.
By the sixth to the fifteenth day the acme has been reached. The alæ of the nostrils are glued together by the drying discharge, and this, with the general swelling of the nasal passages, renders the breathing snuffling and difficult. The lymphatics on the side of the face are usually inflamed and corded, and the same is true of the cutaneous lymphatics of the hind limbs of some other part of the body (farcy). Death usually ensues from suffocation, preceded by the most painful dyspnoea.
Chronic glanders in horses often sets in insidiously, but frequently also it first shows itself by constitutional disturbance, which gradually subsides as the local lesions are formed. Among frequent premonitory symptoms may be mentioned intermittent or continued lameness, oedema of one or more limbs, infiltration of the testicle, cough, and bleeding from the nose. The general health may appear good, and if in good hygienic condition the digestion and nutrition may be sufficient, the body plump, and the skin shining; but there is usually some dulness of the eye, dryness of the coat, lack of endurance, and a tendency to sweat easily and to run down rapidly under hard work or debilitating conditions. The discharge, at first clear, becomes turbid, grayish, sticky, and purulent, tending to agglutinate the hairs and edges of the alæ nasi, and is expelled by snorting in masses. The nasal mucosa, and especially over the septum, is the seat of the peculiar elevations, ulcers, and firm white, condensed deposits resembling cicatrices, usually low enough down to be seen or felt. The submaxillary lymphatic glands are the seat of the nodular enlargement described in acute glanders, and, as in that affection, there may be pulmonary or skin deposits shown by cough or oedema, with swelling and cording of the cutaneous lymphatics with nodules and ulcers.
These cases often maintain this indolent type for years, spreading the infection widely, but they tend sooner or later to develop the acute type, especially under some debilitating conditions.
When the mucous membrane of the larynx and bronchi is first attacked the nasal lesions may be delayed for a time, but the cough, the variously colored tenacious expectoration, the excessive tenderness of the larynx, and the nodular enlargement of the adjacent lymphatic glands, with the general ill-condition, suggest that which is later confirmed by the specific lesions in nose and skin.
When the affection is confined to the bronchia and pulmonary parenchyma, there are the usual signs of bronchitis, disturbed breathing, with hard, soft, mucous, or dry husky cough, and blowing, mucous or sibilant râle, at points crepitation, and at others some diminution of murmur and resonance. The breath is mawkish or fetid, and expectoration more or less sticky and charged with bacilli; but all these symptoms are at times equivocal, and inoculation alone can attest the true nature of the disease. This should be practised by preference on a donkey or an old horse in poor condition but with general good health. Then the disease shows itself in the acute form in six days. If solipedes are not available, rabbits or guinea-pigs may be used for inoculation.
In acute cutaneous glanders or farcy, premonitory symptoms resemble those of ordinary acute glanders, which indeed is usually present as well, and always supervenes before farcy terminates in death. The local lesions consist in inflammation of the lymphatic vessels, which become like firm cords, the appearance at intervals along these cords of rounded glanderous nodules varying in size from a pea to a hickory-nut, and with a marked tendency to ulceration and the formation of hot, painful oedematous swellings. The swelling of the lymphatics appears by preference in the lower part of a hind limb, and the first nodules may be near the fetlock or tarsus. The ulcers forming about the sixth day have a yellowish-white appearance with red points and raised irregular borders, and the discharge is grumous and viscous, with a yellowish or reddish tinge. The disease extends toward the body, the upper air-passages become involved, and death speedily follows.
Chronic cutaneous glanders, chronic farcy, usually begins by a local swelling, mostly of the fetlock, in the midst of which a careful examination detects a small glanderous nodule. This tardily softens, ulcerates, and discharges the characteristic ichor, the lymphatics leading up from it become thick and rigid (corded), and new nodules appear. Though very indolent, these finally tend to ulcerate, and in time oedematous swellings appear in the vicinity or at distant parts of the body, with nodules at intervals. This will go on for months, or even for years, and recoveries occasionally take place, while in other cases, and especially when the conditions of life are bad, acute glanders supervene.
MORBID ANATOMY.—The lesions consist essentially in a cellular growth in the connective tissue, determined by the presence of the specific poison, and in destructive changes in the elements of such growth—softening, fatty degeneration, ulceration, and discharge. In certain cases of nasal glanders at the earliest stage there is merely an increased proliferation of the mucous corpuscles, which become more granular or purulent. Soon, however, the fibro-vascular layer is involved, the affected part being the seat of dark bluish congestion, and of the proliferation of small rounded lymphoid cells, comparable to those of the early stage of tubercle, and enclosed in more or less dense fibrous areolæ. The common nasal nodule or patch has a soft velvety surface, dirty gray or grayish yellow, and the lymphoid cells are so circumscribed in nests that when soaked in water the cells are washed out and the fibrous reticulum is left hollowed out like a honeycomb. In this fibrous reticulum are many spindle-shaped and a few rounded cells. Its vascularity is easily demonstrated by injection. The centre of each nest is the palest part of the mass, and unless stained by extravasation it contrasts with the reddish areola. These islets of lymphoid cells, at first isolated and each the size of a pin's head, may enlarge and become confluent, forming the larger nodules. With this increase the centre of each becomes turbid, and the cells are found to have become granular and fatty, and to have in part broken up into a granular débris. This characterizes the period of ulceration, and erosions and ulcers follow in ratio with the extent of the neoplasm and the rapidity of its growth. If the growth is tardy, the ulcer, with irregular eroded and everted edges, may remain for some time stationary or even recede, while if rapid, new tubercles form around the margin of the first, and by the disintegration of their elements the ulcer is continuously extended. The lesions are especially common on the septum nasi and turbinated bones. Similar lesions may be found in the nasal sinuses or larynx.
The nodules found in the lungs strongly resemble miliary tubercles, but are usually less numerous. As in the nose, they have a punctiform, central, grayish, turbid portion, encircled by a more translucent ring, surrounded in its turn by a vascular area. They are also composed of the same granular rounded cells, though they may, especially in the chronic forms, have undergone caseous, fibrous, or calcareous degeneration. The acute tubercles are often surrounded by circumscribed pneumonia with considerable exudation. They are distinguished from genuine tubercle by their vascularity and by the absence of giant-cells.