526 



DISEASES OF SWINE 



instead of spitting it out, as in the case of human beings, the 

 sputum is swallowed and passes out with the feces. In this way 

 the feces of tuberculous cattle becomes a very productive source 

 of tuberculosis infection in hogs. In dairy districts a large per- 

 centage of cows are often tuberculous, and as it is the usual custom 

 to allow hogs to follow the cattle in the same feed lot, tuberculosis 

 of the hogs is bound to follow. 



Another very common means of carrying the disease to the 

 hog is through milk. Milk from dairy farms, or from any cow, for 

 that matter, may contain large numbers of tubercle germs. In 

 the creamery districts the milk from an entire community is 



Fig. 80. — Bacillus tuberculosis, 

 human, in pus from lung. Zettnow 

 prep. (Kolle and Wassermann). 



Fig. 81. — Bacillus tuberculosis, 

 bovine, in a section of the peri- 

 toneum (Frankel and Pfeiffer). 



hauled to the creamery, the cream separated out, and the skimmed 

 milk run into a large vat. From this vat each farmer draws off 

 his share and takes it back home to feed to his hogs. Now, if 

 any of the milk brought to this creamery is from tuberculous cows, 

 and in almost every case there is bound to be some of it that does 

 come from cows suffering with the disease, the germs are scattered 

 through the entire skimmed-milk tank, and are carried in this 

 manner to every farm that sends milk to the establishment. It 

 is for this reason that such large numbers of swine coming from 

 the dairy districts are affected with the disease. 



Tuberculosis is predisposed to by insanitary conditions in 



