348 CLEAN MILK 



Those animals in which the temperature does not rise to 103 deg. 

 F. within fifteen, or at most twenty, hours after the injection, may be 

 considered free from tuberculosis. When the temperature is between 

 103 deg. and 103.8 deg. the test is doubtful, and the animals should be 

 re-tested after three months. 



When the temperature rises gradually to 103.8 deg. F., or over, 

 within fifteen hours after the injection, the animals may be considered 

 positively affected with tuberculosis, providing this constitutes a rise 

 of two degrees over the maximum temperature recorded before the 

 injection. 



Before admitting newly acquired cows to a herd they should be 

 kept by themselves until tested twice with tuberculin without re- 

 acting. This is necessary because cows may not react in the early 

 stage and because previous treatment with tuberculin may prevent 

 tuberculous cows from reacting. Therefore, after a first negative 

 test the cows are kept by themselves for three months, when a second 

 test is made with three times the ordinary dose. Milk may be sold as 

 certified from these animals, however, after the first test with a 

 negative result. This is the rule : in re-tests three times the usual 

 dose is injected, and in old and emaciated animals double the ordinary 

 amount is used. 



The average dose of tuberculin, as prepared and diluted for 

 immediate use by the U. S. Government, is 2 c.c, or about one-half 

 dram, representing 0.25 c.c. of pure, old tuberculin. 1 to 1.5 c.c. 

 may be given to yearlings and two-year-olds, according to size, and 

 bulls and large animals may receive 3 c.c. of tuberculin. Tuberculin 

 should be kept in a cool, dark place and be rejected if it becomes 

 cloudy. While testing cattle may be done by the laity, it had much 

 better be done by a competent veterinary surgeon, as there are many 

 exceptional cases which can in no way be properly interpreted by 

 the layman. 



