BOVINE TUBERCULOSIS 287 
BOVINE TUBERCULOSIS 
In recent years, owing largely to the feeding of swine with 
creamery refuse, the disease is coming to be somewhat common 
among swine. But it is among cattle that the trouble is most 
widely distributed and of the most serious import. In cattle it 
attacks chiefly the glands of the neck, the glands of the intestinal 
tract, and the lungs. It may be located in the udder; and in these 
cases the milk of the animal becomes a source of danger. Fortu- 
nately, the percentage of cases of udder disease is comparatively 
small. In cattle it rarely attacks the bones, joints, or muscles. 
METHODS OF DISTRIBUTION 
Tuberculosis is contagious. By this is meant that the relation 
of the bacillus to the animal is such that there is an easy means 
of communication between one animal and another under the 
ordinary conditions of life. The knowledge of this fact in regard 
to human consumption has been of great value, since it has been 
followed by a steady decline in the amount of the disease. Such 
knowledge has not yet reduced the amount of bovine tuberculosis. 
We can easily understand the methods of contagion when we 
remember that the bacilli are discharged from any of the open 
tubercles. If the disease is located only in an internal lymphatic 
gland it may not result in breaking down the gland, and there may 
be no discharge. Under this condition there is no contagion from 
one animal to another. But if it be located in the lungs the bacilli 
will be discharged into the air passages and pass through the 
trachea into the mouth. They will then infect all the discharges 
from the mouth and nose. It is true that the cow does not expec- 
torate, but by putting her nose in the drinking trough she will be 
sure to contaminate the drinking-water, and when she licks an- 
other animal, as she will be sure to do if she stands near others, 
she will leave some of the bacilli clinging to the second individual, 
ready to begin their mischief if they chance to get carried to a 
susceptible part, as they are very likely to do by being swallowed. 
