Tubercles of the Skin. These are not very uncommon in cattle being the counterpart of the tuberculous warts and ulcers of the hands of butchers, tanners and others that handle the products of diseased animals. They may show as little pea-like nodules in the substance of the skin, or immediately beneath, very commonly on the side of the abdomen, where their presence in life furnishes a useful suggestion, as enlarged masses forming raw, warty projections with centres of caseation, or as clusters of warty-like growths of this kind (grapes).
Tuberculosis of the Muscles. This is comparatively rare in cattle, though by no means unknown, appearing as tubercles of the size of a pea and upward, in or between the muscular masses, often showing a caseated centre.
Tubercle of Lymph Glands. No organs in the body suffer more than the lymph glands as they receive through their afferent trunks and develop the bacilli coming from any adjacent tissue to which they are subsidiary. There is also evidence to show that bacilli entering from the lungs or bowels may pass through these without apparent effect to develop in the connected lymph glands. The frequent infection of the pharyngeal, bronchial, mediastinal and mesenteric lymph glands has been already sufficiently noticed, and if the other groups suffer less it is mainly because the tissues from which they derive their lymph are less frequently infected. An intimate knowledge of the different groups of lymph glands is a most essential prerequisite to the diagnosis of tuberculosis in life, and no less to a satisfactory post mortem examination. The order of relative susceptibility and importance is somewhat as follows: Bronchial, mediastinal, mesenteric, hepatic, sublumbar, mammary inguinal, subdorsal, phrenic, intercostal (especially the first and second), pharyngeal, parotid, submaxillary, prescapular, prefemoral (stifle), prepectoral, axillary, cubital and popliteal.
Relative Frequency of Tubercle in Different Parts in Cattle. The following table gives the seat of tubercle as noted by a number of observers. It is open to the objection that it is the result of examination for diagnosis, and therefore gives the most obvious rather than the complete list of lesions. Examination of the brain, bones, deep muscles and intermuscular glands, etc., was usually omitted. Again, as the animals were often steers, the indications as regards the generative organs are unreliable. The œsophagostoma nodules on the bowels have been so often mistaken for tubercles that I have omitted all reference to intestinal tubercle.
| DISTRIBUTION OF TUBERCLES IN DIFFERENT ORGANS OF CATTLE: PER CENT OF AFFECTED CATTLE. | ||||||||||||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| % Right Lung. % Left Lung. | % Mediastinal Glands. % Bronchial Glands. | % Costal Pleura. % Visceral Pleura. | % Mesenteric Glands. | % Liver. | % Spleen. | % Uterus. | % Lumbar Glands. | % Liver Lymph Glands. | % Peritoneum. | % Pharyngeal Glands. | % Diaphragm. | % Stomach. | % Udder. | % Iliac and Inguinal Glands. | % Lymph Glands of Udder. | % Lymph Glands of Flank. | % Lymph Glands of Shoulder. | % Pericardium. | % Heart. | % Kidneys. | % Bones. | % Muscles. | % Larynx. | |
| German Abattoirs, | 75 | 29 | 47–55 | 28 | 19 | 10 | 5 | 1 | 4 | 0.2 | 0.16 | 1 | 0.06 | 0.9 | 0.7 | 0.1 | 0.13 | |||||||
| Pearson, (Penna), | 63–57 | 60.7–33.8 | 22 | 23.25 | 20.7 | 5.7 | 5.5 | 10.3 | 14 | 15.15 | 11.4 | 7.2 | 8.75 | 13.5 | 9 | 7.75 | 8.2 | 2.1 | 0.4 | |||||
| Bryce (Canada), | 77.27 | 56.8 | 11.36 | 11.36 | 40.9 | 45 | 2.27 | |||||||||||||||||
| Reynolds (Minn. Agr. Ex. Station), | 89.4 | 33.3–64.9 | 79 | 12.5 | 35.4 | 27 | 8.3 | 18.7 | 16.6 | 2 | ||||||||||||||
| Law (N.Y. Grade Herds), | 34.8 | 64 | 6.4 | 9.6 | 1.6 | 17.7 | 6.4 | 6.4 | ||||||||||||||||
| Nelson (N. J. Exp. Station Cows), | 33.9 | 28 | ||||||||||||||||||||||
| Russell (Wis. Exp. Station), | 55 | 72.4 | 24 | 10 | 31 | 6.9 | ||||||||||||||||||
| Stalker & Niles (Ia. Exp. Sta.), | 36 | 61 | 8.3 | 5 | ||||||||||||||||||||
| Reick (Leipsic), | 100 | [[2]]57 | 83 | 18 | [[2]]57 | 17 | 52 | 9 | 49 | |||||||||||||||
[2]. All serosæ.
Swine. The lesions in swine, though essentially like those in cattle, differ in some particulars. The primary tubercles are more commonly pharyngeal or intestinal and mesenteric, in keeping with infection by ingestion; caseation will often proceed to liquefaction, so that the tubercles appear like grumous abscesses with irregular outlines and vascular growths on their walls; there is less tendency to cretefaction than in cattle; the muscular and intermuscular tissues and the lymph glands are far more frequently affected; ulceration of the pharyngeal and intestinal mucosæ is more common. The lungs, liver, spleen and visceral lymph glands are very subject to tubercle, the kidneys, uterus and testicles somewhat less so, and the nerve centres least of all. The serosæ are often involved and the seat of clusters of vascular or caseated neoplasms (grapes). The bones and joints also suffer, particularly in young growing animals.
Horse. The horse suffers much less frequently than cattle or swine, probably largely because of his outdoor life, his better tone as the result of muscular work, and the absence of the excessive milk secretion which is secured from cows and of the dangers from ingestion that attend on swine. Yet, according to Nocard, it is even more susceptible, and the disease once established is liable to advance more rapidly to a diffuse generalization. The lesions in the lungs and abdominal cavity resemble those of cattle, both in nature and abundance; tuberculous polypi and ulcers are more common; the visceral lymph glands (bronchial and mesenteric) are early and severely attacked; the liver and spleen suffer extensively, the serosæ somewhat less so; lesions have been noted in the vertebræ, skin and muscles (Cadiot). In rare instances tubercles have been seen in the heart, and the aorta has been atheromatous (Cadiot). Necrotic degeneration, caseation and cretefaction occur as in cattle.
Sheep and Goat. Tuberculosis is infrequent in the goat and especially so in the sheep, owing perhaps largely to open air life and their predilection for high, airy pastures. When inoculated they show a marked susceptibility, and under favorable conditions they contract the infection casually. The tubercles may be found in all parts of the body,—lungs, thoracic lymph glands, intestines, mesenteric and sublumbar glands liver, spleen, serosæ, lymph glands at large, vertebræ, etc. There is less tendency to calcification than in the ox, the older tubercles remaining in the caseated condition or bursting and forming vomicæ. A common seat of casual tubercle in sheep is around the throat or on the sides of the cranium or face.
More frequently than in cattle, verminous affections (œsophagostoma columbiana, and venulosum in the bowels, stongylus filaria and rufescens in the lungs, linguatula denticula in the mesenteric glands) are mistaken for tuberculosis, hence the necessity for a careful investigation into the nature of the neoplasm, the presence of the tubercle bacillus, and the absence of the worms and their eggs. Except in the case of the linguatula the lymph glands are little affected by the worms.