TUBERCULOSIS 303 



produced In' infection, or a better term would be transmission of tubercle 

 bacilli, direct or indirect, from one subject to another. 



While it is well known that tuberculosis of man and of certain 

 domestic animals, such as cattle, is very common, it is rather rare in dogs. 

 A number of schools have found that only from 2 to 5 per cent, of all of the 

 animals brought to the clinics were affected with tuberculosis. Dogs seem 

 to possess more power of resistance and are able to throw off the disease. 



Certain experiments by inoculation and inhalation have demon- 

 strated the fact that one-third of the cases develop the disease, and the 

 feeding of tubercular matter in the food invariably produced negative 

 results. Considering the rarity of this disease in the dog, we will not 

 give any detailed explanation of any length concerning its etiology, 

 pathological anatomy, etc. 



Etiology and Pathological Anatomy. — A number of observers agree 

 to the fact that, as a rule, an animal affected with tuberculosis has been 

 at some time near or in the vicinity of some person who was in an ad- 

 vanced stage of consumption. In such cases the bacilli may be intro- 

 duced in the form of fine dust and be respired into the lungs or may be 

 taken up by the intestines, finding their way into the bowels mixed with 

 food. In one ease which the writer observed there Avere tuberculous 

 ulcers in the parotid region, and also tubercular deposits in the lymphatic 

 glands of the neck. The disease appears in the dog in the form of an 

 acute or local tuberculosis. The disease may be found in the lungs, 

 the mesenteric glands, the intestines, liver, kidneys, and peritoneum, and 

 in rare instances affecting the entire body. 



Pulmonary Tuberculosis. — This presents numerous anatomical alter- 

 ations: over the entire lung we may find firm round gray nodules (miliary 

 tuberculosis), or they may break down, forming caseous nodes and 

 cavernous hollows or there may lie a chronic indurated broncho-pneu- 

 monia; more rarely we find chronic interstitial indurating pneumonia 

 with secondary alterations, acute and chronic bronchitis, peribronchitis, 

 bronchiectasis, pulmonary hypera^mia, emphysema, and frecjuently 

 adherence of the lung to the pleural wall. 



In nearly 50 per cent, of all cases, the lymphatic glands of the 

 thorax, especially the bronchial glands and the glands which are located 

 above and behind the mediastinum, are invariably infected to a marked 

 degree with tubercular deposits, and are found to be very often enlarged, 

 forming large tumor-like masses. These consist of a lardaccous tissue, 

 grayish-white in color, and generally contain a centre cavity filled with 

 a cheese-like mass. True cheesy tuberculosis is rather rare in the dog, 

 but, on the other hand, we find a peculiar process of absorption of the 

 tissues, foi-ming white masses, which on examination are found to be 

 tuberculous deposits. 



