10 
Farmers’ Bulletin 1009. 
the power to resist the invasion of the organisms. Stabling animals 
in dark, poorly ventilated, and dirty barns helps to spread tuberculosis 
among the stock whenever the germs are present. Introducing a 
tuberculous animal is almost sure to give the disease to healthy 
animals in a short time. If the healthy animals drink water from 
the same trough or bucket the tuberculous animal uses, and if that 
animal is coughing up tuberculous sputum, all the animals are in 
serious danger of infection. Any condition that produces constant 
strain upon the systems of animals, such as the continued forced 
lactation periods of dairy cows, renders them fit subjects for the de¬ 
velopment of tuberculosis. 
HOW CATTLE BECOME INFECTED WITH TUBERCULOSIS. 
The tuberculous cow is the greatest source of danger to healthy 
cattle, and inasmuch as it can not be determined just when that 
animal becomes a “spreader” of the germs, unless daily microscopic 
tests are made of the discharges from the body, and the milk is also 
examined microscopically, it is unsafe to keep it with healthy cattle. 
No cattle from outside sources should be introduced into a healthy 
herd until they have been tuberculin tested and found free from 
the disease. Unquestionably more healthy cattle acquire tubercu¬ 
losis by coming into contact with affected animals than in any other 
Fig. 4.—A tuberculous heifer. The gland at the shoulder was diseased and discharging tuberculous pus. 
