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RURAL VETERINARY SECRETS 



THE NATURE AND APPLICATION OF TUBERCULIN TEST 



Tuberculin is tlic sterilized and filtered glycerin extract of cul- 

 tures of tubercle bacilli. It contains cooked products of the growth 

 of these bacilli, but not the bacilli themselves. Consequently, when 

 this substance is injected under the skin of any animal it is abso- 

 lutel}^ unable to produce the disease, cause abortion, or otherwise 

 injure the animal. In case the injected animal is tuberculous, a de- 

 cided rise of temperature will follow the use of tuberculin. 



In practice the tuberculin test is applied by first taking a suf- 

 ficient number of temperatures, usually three, at intervals of two 

 hours, to ascertain the normal variation of temperature of the ani- 

 mal to be tested. The dose of tuberculin (which should always be 

 specified on the label) is then injected hypodermically between 8 

 and 10 p. m. on the day of taking the preliminary temperatures. On 

 the following day the "after" temperatures are recorded every two 

 hours, beginning at 6 a. m. and continuing until twenty hours fol- 

 lowing the injection. 



Typical tubercular heifer. 

 Photo by author. 



