TUBERCULOSIS. 365 



sible absolutely to get rid of this disease by any method of 

 limiting its facility of distribution, it is certainly possible to 

 reduce it, and to protect many an animal that would other- 

 wise contract the disease. Our brief consideration of this highly 

 important matter must be given from two standpoints: (i) 

 The healthy herd, (2) the infected herd. 



1. Protection of a Healthy Herd. If a farmer has a herd in 

 which the disease has not appeared it is of especial interest to 

 him to keep his herd in this condition ; for once the disease 

 has entered the herd it is very difficult to get rid of it. So 

 long as he can keep his animals from becoming contaminated 

 from without, he may be practically sure that the disease will 

 not appear among them. All evidence shows that tuber- 

 culosis does not develop spontaneously in a herd of animals, 

 but always comes by being introduced from the outside. A 

 farmer who can raise his own cattle, and can properly pro- 

 tect them from contact with outsiders, need have no tuber- 

 culosis among them. But to protect the herd requires some 

 knowledge and considerable vigilance. To prevent the en- 

 trance of the disease into his herd from without the farmer 

 must exercise care in four directions. 



First : In buying stock he must be sure not to purchase in- 

 fected animals. This is perhaps the greatest difficulty, for it 

 is most commonly by purchase that the disease is introduced 

 into a herd. There is only one way by which he may be sure 

 that he is not purchasing infected cattle and this is by a 

 proper tuberculin test, under the guidance of a reliable veteri- 

 narian. Unfortunately, with the numerous conflicting rules of 

 different states and countries, it is not always possible to make 

 use of this test. But one thing is certain. No farmer can be 

 confident of keeping his herd free from this disease unless he 

 can be assured by the tuberculin test that he is purchasing 

 animals freed from every suspicion of the disease. Careless- 

 ness in this regard will surely be regretted. 



