THE DAIRY COW 163 



tions and their average temperature is ol^tained by taking 

 temperatures at 10:00 a.m., 2:00 p.m. and 6:00 p.m. and averag- 

 ing these. In taking temperatures the thermometer is in- 

 serted in the rectum. The thermometer should be left in 

 about two minutes. If an operator uses several thermometers 

 he can test a large herd at once. The same evening the cows 

 are inoculated with tuberculin at the rate of 2 cubic centimeters 

 for each 1000 pounds of live weight. The cows are inoculated 

 from 8:00 to 10:00 o'clock in the evening. The tuberculin 

 is injected under the skin with a hypodermic syringe. The 

 point selected for the injection is back of the shoulder or at 

 any other place where the skin is loose and there are plenty 

 of blood vessels underneath. The needle of the syringe should 

 be put through the skin so that the point is free underneath. 

 The material is absorbed by the blood and carried throughout 

 the body. If the cow has tuberculosis this tuberculin will 

 cause a fever. 



Temperatures are taken the following day at intervals of 

 two hours beginning at 6:00 a. m. If the temperature rises 

 during the day and falls again toward evening and if the rise 

 is 2 or more degrees or if it goes to 104 or 105, an animal almost 

 certainly has the disease. It must not be forgotten, however, 

 that the fall in temperature above mentioned is necessary. 

 Sometimes cows are kept under abnormal conditions or again 

 they may be sick otherwise so that the temperature goes up. 

 But this would not be an indication of tuberculosis. To get a 

 reaction the cows must be kept under normal conditions, must 

 be in normal health and there must be a rise and a fall in 

 temperature. But the fall as a rule is not back to normal by 

 the close of the day. 



When the test is properly carried out it is almost absolutely 

 accurate. But sometimes when cows are in advanced stages 

 of the disease they will not respond to the test. Also, one 

 test should not follow the one preceding for four or more 

 months. 



It is said that dishonest people sometimes keep their cattle 

 ''plugged.'' This means that they keep injecting tuberculin 

 into them at intervals of four months or less so that they will 

 not respond to tests by State officials or others. 



