330 SWINE PRACTICE 



of tuberculosis. In 1865 Villemin proved the infectiousness of the 

 disease, while Koch discovered the tubercle bacillus in 1882, thus 

 establishing firmly the theory of the infectiousness of tuberculosis. 

 The study of tuberculosis has been advanced and its recognition clin- 

 ically has been made possible by the use of tuberculin, which was dis- 

 covered by Koch in 1890. In 1901 he startled the scientific world by 

 announcing at tlie tuberculosis congress in London that human and 

 bovine tuberculosis were separate and distinct diseases, a statement 

 that was responsible for the organization of different scientific bodies 

 that, after careful investigation, reported that although there may be 

 some slight difference between the tubercle of human and bovine 

 origin, the disease produced is the same and that the disease is inter- 

 transmissible between animals and man. 



Occurrence. — Tuberculosis is becoming very prevalent among swine. 

 This is due to the fact that the dairying industry is becoming more 

 extensive and the by-products of milk are used for swine feed. A 

 relatively large percentage of dairly cattle is tuberculous, and the in- 

 fection gains entrance to the milk on filth tliat is contaminated with 

 infected discharges, such as saliva and feces. The organism may also 

 be eliminated direct from the mammary gland into the m.ilk. 



Swine from some sections of the United States have been found by 

 experience to be so extensively tuberculous that some packers will 

 buy them only subject to post-mortem inspection. 



In Germany from 2.46 to 2.81 per cent of swine slaughtered at 

 abattoirs are condemned on account of tuberculosis. The disease is 

 very prevalent in Belgium, France, Norway and Sweden, and procine 

 tuberculosis is a common disease in the British Isles. According to 

 the annual report of the Bureau of Animal Industry for the fiscal 

 . year of 1911, 29,920,260 carcasses of swine were inspected in abattoirs, 

 and of that number 31,517 carcasses and 870,361 parts were con- 

 demned on account of tuberculosis. And, for the fiscal year ending 

 June 30, 1919, 44,398,389 hogs were slaughtered at official establish- 

 ments, of which 65,838 were condemned, and tuberculosis in some 

 degree was found in 4,103,377, or over 9 per cent of the 44,398,389 

 swine slaughtered were affected with tuberculosis. The disease is 

 becoming more extensive in swine in the United States and should 

 receive more consideration tlian it does, as the economic loss annually 

 is enormous. 



Etiology. — The cause of tuberculosis is the tubercle bacillus or the 

 Bacillus of -Koch, ■ It is a rod-shaped organism from 1.5 to 4 microns 



