FORMS AND LESIONS OF GLANDERS IN SOLIPEDS.
Glanders appears in two primary forms—acute and chronic, and each of these is further divided according as the lesions are exclusively or mainly seated in one part of the body or another. The generic term glanders is habitually used to designate that form in which the lesions are situated in the nose, the nasal sinuses, and the submaxillary lymphatic glands—nasal glanders. When the principle lesions are situated in the lungs and lymph glands of the chest, the case is one of pulmonary glanders. When the skin and subcutaneous lymphatics are most prominently affected it is known as farcy or cutaneous glanders. When the skin and nose are simultaneously affected the name farcy glanders is sometimes applied. But as the bacillus may enter by very varied channels the primary lesions may appear in still other organs. Thus in stallions the first symptom is often a glanderous orchitis. In other horses it may be a glanderous arthritis, and in still others infected by ingestion it may be an abdominal infection.
Symptoms of Nasal Glanders in Solipeds. Acute. After an incubation of three to five days the subject shows prostration, weariness, stiffness, erection of the hair, and even tremor or shivering, inappetence, thirst, hyperthermia, rapid pulse, weeping eyes, the discharge becoming purulent, snuffling breathing, and a discharge from the nose, at first serous, with a remarkable viscidity which tends to glue together the long hairs or even the margins of the nostrils. This discharge may be reddish, greenish, or brownish and may become distinctly purulent and opaque. The alæ nasi are swollen, hot and painful, and the mucosa red, congested, thickened, with a blackish or violet tint especially along the median part of the septum nasi. On these, violet patches appear on the second or third day, pronounced elevations of very varying size indicating the centres of active hyperplasia. They are usually yellowish or grayish, surrounded by a deep violet areola, and may become confluent forming patches. The centre of each undergoes rapid degeneration, forming a rounded ulcer with salient edges, a yellowish base, more or less pointed or streaked with red, and a viscid seropurulent or bloody discharge which may concrete in crusts or scale. The whole septum may become one continuous ulcer with excavations of various depths surrounded by hyperplastic elevations, and involving not only the mucosa, but even the cartilage and leading to perforations.
From an early stage of the attack the submaxillary lymphatic glands and the investing connective tissue become swollen, forming a mass of firm bean- or pea-like nodules, with no excessive heat nor tenderness, and with little disposition to suppurate and discharge. If this has lasted for some time the glands often become more firmly attached to adjacent parts (maxilla, tongue) by the contraction of the exudate.
The swelling of the alæ nasi also often extends to the skin of the face, and firm, rounded cords formed by the swollen lymphatics stretch upward toward the eye, or the submaxillary glands. Upon the turgid lymphatics may appear more or less rounded nodules from the size of peas to hazel nuts, which, unlike the submaxillary glands, tend to soften, burst and discharge a viscid, glairy, sanious liquid.
At the same time the morbid process is liable to show itself in the cutaneous lymphatics of one limb, usually a hind one, in the form of firm cords, with degenerating or ulcerous nodules (farcy buds) and pasty patches. Or the throat or lungs may become involved, with local swellings, violent cough, dyspnœa and fever. The swellings of the cutaneous lymphatics usually follow the course of the veins, in the hind limbs the branches of the saphena, and extend from below upward, and the first nodules may be on the fetlock or hock.
Symptoms of Chronic Nasal Glanders in Solipeds. The chronic form of the disease follows an indolent course, and local symptoms are often so slight or equivocal that the true nature of the malady is unsuspected. If the patient is well fed and cared for and not overworked, the malady may run a course of three, five or seven years, and the victim may pass through many hands leaving infection in every stable it occupies. Diagnostic symptoms, more or less clear, may be obtained from the discharge; the lesions of the mucosa and the submaxillary glands.
The nasal discharge may be bilateral, but if confined to one nostril is strongly suggestive of glanders. It may be profuse or scanty, continuous or intermittent, of a yellowish, purulent tint, or greenish, or grayish and with a special tendency to viscidity. In some indolent cases the nostrils may be clean but if there is any matting of the long hairs, or adhesion of the alæ nasi, the case is specially suspicious. If it is sanious, flocculent, or bloody it is all the more characteristic, and suggests the supervention of an acute attack.
The lesions of the pituitary membrane are varied. Hyperæmia of a purple or violet color is common, especially along the septum, and the mucosa is liable to be somewhat tumid or œdematous. Nodules the size of a pin’s head, a pea or larger appear inside the inner ala, or on the septum or turbinated bones, and at first red from extravasation and, as it were vesicular, become grayish, whitish or yellow with points of red and surrounded by a deeply congested areola. Larger nodules forming in the submucosa approach the surface and stand out the size of the tip of the finger and with the same general character as the smaller. Sooner or later these degenerate and form ulcers which bear a resemblance to those of acute glanders but are less angry, and when small and solitary may be taken for simple erosions. In other cases they become thickened and indurated with sharply defined projecting margins, and a yellowish base with points or lines of red. The presence of red, black, green, or brown crusts may also be noted.
Another lesion frequently observed in indolent cases is a cicatricial white spot or patch in which the hyperplasia has become partially developed into tissue and shows no tendency to ulcerate. The mucosa may even be drawn or puckered around the cicatrix, making the illusion all the more complete.
The submaxillary swelling is even less sensitive than in acute glanders and produces the same sensation as of an aggregation of small, hard, pea-like, masses with no tendency to ulcerate.
Symptoms of Cutaneous Glanders (Farcy) in Solipeds. Acute cutaneous glanders has been already referred to under nasal glanders. The chronic type is often less characteristic, yet may be detected by careful observation of the symptoms. The main symptom may be the swelling of a joint with more or less engorgement of the limb from attendant lymphangitis. There can usually be detected around the margins of such swellings firm, tender cords representing the larger lymphatic vessels and often branching in their course. In the absence of the engorgement, or when it is slight, these cords may be the main evidence of the disorder, and in the hind limb usually follow the course of the flexor tendons on the inner side of the digit, metacarpus and thigh. At intervals along the line of the cords appear nodular masses (farcy buds) varying in size from a pea to a hen’s egg, and showing a great disposition to soften and discharge a glairy, sanious or more or less bloody liquid. The inner sides of the fetlock and tarsus are favorite seats of these nodules but they may form at any point. On the trunk also the corded lymphatics and nodules follow the lines of the veins and lymphatics, and here there may be the complication of large intermuscular abscesses often in connection with the groups of lymphatic glands.
Latent or occult glanders is often met with, the indolent, specific lesions being confined to some internal organs, like the larynx, lungs or womb, or to the testicles, the nasal diagnostic symptoms being absent. A chronic cough, with a slight purulent discharge from the nose, a chronic leucorrhœa, a swollen testicle, or simply a persistent low condition or weakness without apparent cause, may be the only indications, and special means of diagnosis are demanded.
Special Means of Diagnosis. In occult cases, the disease may be identified by inoculation, or by the mallein test.
Inoculation is best performed on a very susceptible animal. If the suspected discharge from the nose, vagina, open sore or preferably from a freshly incised nodule is inoculated subcutem in the flank of a male Guinea pig, or better in the peritoneum, there develops a local ulcerous sore and on the second or third day a violent orchitis in which pure cultures of the bacillus can be obtained. The caseous and purulent centres are found not only in the testicle but along the line of the spermatic cord, affecting the tunica vaginalis and connective tissue. Death usually follows in four to fifteen days. The cat and dog can also be utilized, inoculation being made on the forehead. Old wornout, but otherwise healthy asses, and even horses make very available subjects, inoculation in the nose speedily developing acute glanders. In the absence of a good subject the suspected animal is sometimes availed of, scarifications being made in the nose and the morbid product rubbed in freely. The rapid development of ulcerous wounds is characteristic. If, however, the case is chronic, and if a fair measure of immunity has been acquired this test may prove misleading.
Test by Mallein. Mallein is the sterilized and concentrated toxic product obtained from a pure culture of bacillus mallei in a peptonized glycerine bouillon. When injected hypodermically in a small physiological dose this has no effect on a sound horse, but in one affected with glanders it develops in several hours an extended swelling in the seat of inoculation, hot, tense and painful, which continues to enlarge for 24 to 36 hours and does not subside for 4 or 5 days. From the margin of the swelling, swollen lymphatics may often be traced running toward the adjacent lymphatic glands. There is also decided dulness, prostration, inappetence, staring coat and tremors. The body temperature rises 1.5° to 2.5° and upward from the eighth hour after inoculation attaining its maximum from the tenth to the eighteenth hour and subsiding slowly to the forty-eighth to the sixtieth.
Mallein must be used under precautions like tuberculin. It must be obtained freshly prepared from a reputable maker. If preserved for months its force may be largely lost. The animal to be tested should be in his customary environment, and not just arrived from a railroad journey nor other cause of excitement. He must not be fevered as any rise of temperature is then equivocal, and a fall of temperature, which sometimes occurs in the febrile system under mallein, is no sure evidence of glanders. Reaction sometimes fails in advanced cases of glanders, but in such a case other symptoms are usually diagnostic so that mallein is superfluous and should not be misleading. The greatest care should be taken to prevent infection from the syringe, nozzle, skin, hands, etc., as other infections may give rise to local swelling and hyperthermia (see tuberculin test). If a first test leaves the matter in doubt, the animal should be secluded and tested again in a month (some prefer 3 months).
Pathological Anatomy. The colonization of the bacillus mallei in a tissue usually determines a concentration and multiplication of leucocytes, so as to form rounded nests of small lymphoid cells in a scanty fibrous network. These may be miliary or by aggregation they form masses the size of a pea or larger, which bear a close resemblance to the neoplasms of tuberculosis. As in tubercle the central cells of the group, degenerate, forming a granular fatty debris, and constituting an ulcer or abscess. In certain cases with a proliferation of fibrous tissue a cicatricial material is developed. Another characteristic lesion is the occurrence of hyperplasia in the walls of the lymph vessels so as to constitute firm tender cords, and the infiltration of the adjacent lymphatic plexus.
In the nasal mucosa the bacilli form prolific colonies at different points of the membrane and submucosa with the active production of lymphoid cells, followed by granular fatty degeneration and ulceration. Hence may be found different lesions representing the different stages. First there may be miliary deposits with clear contents and standing out like grains of sand. Then there are the larger pea-like nodules with congested vessels and minute hæmorrhages, but made up largely of the nests of lymphoid cells. These may bear on the surface a distinct blood extravasation, or the epithelium may be raised from the corium layer by a liquid exudation. The more advanced nodules show the centre light colored, grayish or yellowish with a distinct granular degeneration of the cells. Later still the degeneration involves the superficial layers and epithelium and an open ulcer is formed with a strong tendency to extend in depth and width. The formation and degeneration of numerous foci of cell proliferation gives the ulcer a very uneven outline. The continuous growth of fresh centres of proliferation may cause marked elevations between the ulcers, constituting extended patches, or the entire nasal mucosa may be thickened as the result of the morbid deposit. The cicatrices resulting from the apparent healing of deep or extensive ulcers or from a fibroid, transformation of the neoplasm consist of condensed connective tissue with small scattered nests of lymphoid cells and bacilli. In chronic cases the bacilli are very scanty.
The mucosa of the Eustachian pouches and tubes, the larynx, trachea and bronchia often present lesions similar to those of the pituitary membrane.
The lungs are usually marked in chronic cases by circumscribed lobular pneumonia, interlobular and peribronchial inflammations and miliary or larger areas of degeneration resembling tubercles. These may begin as a minute congestion and ecchymosis, which later shows in the centre a translucent or gray mass of lymphoid cells, with a surrounding area of congestion. Later still this central mass becomes yellowish and caseated from granular and fatty degeneration and this gradually extends so as to involve the whole area of the nodule. The peripheral portion may condense into a fibroid envelope, but usually this is less smooth and evenly rounded than in the case of an inspissated abscess or bladder-worm. The bacilli are found in the affected tissue but not always abundantly.
In cutaneous glanders the lesions may begin in the papillary layer by active congestion and infiltration and proliferation of lymphoid cells which cause an eruption of rounded papules like small peas that degenerate and soften and form superficial ulcers. When the derma is mainly involved the inflamed area becomes the seat of larger hard nodules which are at first deeply congested, with capillary thrombi, minute extravasations and rapid cell proliferation; later on section they show numerous caseated centres with a dense fibroid framework and surrounded by an area of active congestion and capillary hæmorrhage; later still the caseation and softening has caused rupture of the investing epithelium and the discharge from the ulcerous cavity of a yellowish, glairy, grumous liquid (open farcy buds). Sometimes the nodule undergoes fibroid induration and fails to ulcerate, becoming the counterpart of the cicatrices in the nose. When the infective inflammation extends to the subcutaneous connective tissue, diffuse engorgements and extensive swellings occur from the general infiltration of the abundant lymph plexuses. Lymphoid cells accumulate in the perivascular sheaths and lymph plexuses, the walls of the lymphatic trunks running out of these swellings become swollen and indurated and at intervals, mostly on the seat of the valves there is the proliferation of small round cells to form farcy buds. In chronic cases the fibroid thickening involves the skin, subcutaneous connective tissue and walls of the lymph vessels binding the whole into one dense resistant mass, more or less studded with corded lymphatics, firm nodules, and ulcerous sores.
The lymphatic glands in the line of circulation from the infected centres are constantly involved. Hypertrophy, congestion, serous infiltration, and rapid cell proliferation are present and a section will usually show caseated or caseopurulent centres confined by the outer dense fibrous envelope. Exceptionally, these necrosed contents will escape through an ulcerous opening, forming a deep cavity which is slow and difficult to heal. In the vicinity of these glands and in the loose intermuscular connective tissue abscesses of the size of an egg or an orange or larger are sometimes met with.
Nodules and ulcers are found on the pharyngeal and intestinal mucosa, similar to those of the larynx.
The spleen, and less frequently the liver, may be the seat of caseating nodules exactly comparable to those of the lungs. Glanders of the kidney is rare.
Nodules have been seen on the ventricular endocardium and one case of nodules of the choroid plexus (Boschetti).
In stallions, glanderous, caseating foci in the testicle and dropsy of the scrotum are common, while mares may have similar formations in the mammary glands or ulcers of the vaginal or uterine mucosa.
Infiltrations of the joints and other synovial cavities are not uncommon and glanderous infiltration of the bones with caries is also found. In chronic cases, fragility of the bone is marked, and the blood contains an excess of leucocytes. These may be traced to disease of the bone marrow, as well as of the spleen and lymphatic system.