146 DISEASES OF SWINE 



in most cases of noticeable symptoms that so lit- 

 tle attention is given it. 



Causes.— The specific cause is bacillus tuber- 

 culosis, which was first described by Koch in 1882. 

 The bacilli occur in the form of slender rods 

 having rounded ends singly, in pairs, or in small 

 bundles. They are found in the nodules and 

 tubercles, which they produce in the tissues. 

 There is, perhaps, no disease producing germ that 

 undergoes greater modifications in form and char- 

 acter under various conditions and environments. 

 Even in the same animal, it may take on dififerent 

 forms. There is a wide variation in the types 

 of the germ. It does not form spores, but vacuoles. 



The most important factor in the production 

 of tuberculosis in hogs is the presence of the 

 disease among dairy cattle. The milk from a 

 single tubercular herd, when taken to the cream- 

 ery, may infect a large number of hogs in the 

 neighborhood through the skim-milk, buttermilk, 

 and slops. The percentage of tubercular hogs is 

 greater in places where dairying is an important 

 industry than in other sections of the country, 

 a condition that proves beyond a doubt the above 

 method of infection. A common source of the 

 disease in young pigs, is through the milk of a 

 tubercular mother. 



The feeding of offal to hogs, as is frequently 

 the practice at the country slaughter-house, will 

 cause the disease, because of the germs of tuber- 

 culosis sometimes present in the carcasses, or 



