384 The Diseases of Animals 



bringing oxygen, carrying away the waste, and keeping 

 the quarters dry. Sunlight, fresh air, dryness and 

 cleanliness, with good food, are essentials in preserving 

 a healthy herd. 



The Tuberculin Test 



The most accurate means of detecting tuberculosis 

 in cattle is by injecting a small amount of "tuberculin" 

 beneath the skin. If the animal has the disease, there 

 follows, in about twelve hours, a rise of temperature 

 or fever, which lasts for a few hours and then sub- 

 sides. Tuberculin is a toxin excreted by the tubercle 

 bacillus during the process of its growth. When 

 prepared for use, tuberculin contains no germs of tuber- 

 culosis, and is incapable of producing the disease. 



In testing animals with tuberculin the temperature 

 of the tested subject is taken with a clinical (fever) 

 thermometer every two hours, beginning at 6 A. M. 

 and continuing until 12 p. M., when a small quantity of 

 tuberculin is injected under the skin and the tempera- 

 ture again taken as on the preceding day. If the 

 animal has tuberculosis there is a rise of tempera- 

 ture of two to six degrees Fahr. If the animal is free 

 from the disease the temperature does not rise or vary 

 more than the normal daily variation. Careful attention 

 should be given to the manner in which the temperature 

 rises. A sudden and rapid rise of temperature is to 

 be regarded with suspicion. In a typical reaction to 

 the tuberculin test, the temperature rises gradually for 

 two hours or more until it attains its maximum; then 



