FIFTIETH ANNUAL CONVENTION 115 



tutionally and lose 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 tubercu- 

 lous animal is almost sure to give the disease to healthy ani- 

 mals 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 con- 

 dition 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 development 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 microscopic- 

 ally, 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 ac- 

 quire! tuberculosis by coming into contact with affected ani- 

 mals than in any other way. It has been observed fre- 

 quently that cattle which stand on either side of or face 

 tuberculosis animals in barns are the first to contract the 

 disease. 



The continuous water trough in barns is also account- 

 able to, a very large extent for spreading the disease. Cat- 

 tle may become infected by picking over manure infected 

 with the germs of tuberculosis. Hay, straw, or any other 

 feed contaminated with the germs may give the disease to 

 animals that consume such material. 



Water holes and creeks into which infected milk or 

 the washings from infected milk cans have been dumped 

 may also be a source of the infection. The teat siphon or 

 milking tube, in a number of instances, has been the medi- 



