TUBERCULOSIS OF SWINE 145 



thoracic form is referable to human tuberculosis, the abdominal form, 

 as already mentioned, is more closely allied to the bacillus of avian 

 tuberculosis. 



CANINE TUBERCULOSIS. 



In the dog the disease also occurs in two forms, the abdominal and 

 the thoracic. Many cases have been recorded, the principal lesions 

 mentioned occurring in the liver, hepatic and mesenteric glands, as well 

 as generalized tuberculosis of both lungs and the bronchial glands. 



TUBERCULOSIS OF SWINE. 



The pig is very susceptible to experimental disease, and according 

 to some authors, the scrofulous conditions (see Photograph, Fig. 53) 

 occasionally observed in pigs are due to tuberculosis. According to 

 Nocard the disease in the pig often develops with great rapidity and 

 passes unperceived. In the chronic form the bacilli are rare, and 

 appear to have lost part of their virulence ; and when inoculated into 

 guinea-pigs they produce a disease of slow course, but the period of 

 incubation becomes shortened when the bacilli are inoculated from 

 the first guinea-pig to others in series. 



According to Nocard, nine out of every ten pigs are infected 

 through the alimentary canal. Many investigators have produced 

 the disease by feeding pigs with milk from cows with tuberculous 

 udders. In 1877, pigs were kept under the shambles in San 

 Francisco, and fed on the offal which fell down a shoot. The 

 percentage of tuberculosis that occurred in those swine was beyond 

 conception, the livers and spleen being studded with masses of 

 tuberculous nodules. (For Photograph of a tuberculous spleen of pig, 

 see Fig. 54, and for Photomicrograph of a section of a tubercle from 

 same, see Fig. 52.) 



Tuberculin. The use of tuberculin as a curative agent has not 

 fulfilled the expectations at first anticipated. When injected into healthy 

 persons it has no reaction, but in tubercular patients a pronounced 

 systemic reaction results. Koch has lately produced a new tuberculin, 

 known as TO. and TR., prepared by triturating dried cultures of tubercle 

 bacilli in a mortar without anything being added for a considerable time. 

 The mass is then mixed with distilled water and placed in a centripetal 

 machine, when an opalescent, transparent, whitish fluid is obtained free 

 from bacilli. Trudeau and Baldwin have recently conducted experiments 

 with this new preparation in New York, and found that it still contained 

 living tubercle bacilli, capable of producing tuberculosis in guinea-pigs ; 



K 



