254 MICROBIOLOGY 



Application of tuberculin for diagnosis. The following 

 precautions should be taken in the use of tuberculin. 21 The 

 old tuberculin is employed. 



1. The tuberculin test for diagnosing tuberculosis should 

 not be applied to an animal that is suffering from any other 

 known infectious disease or other conditions giving rise to an 

 elevated temperature, or an animal that is far advanced in 

 pregnancy. 



2. The animals to be tested should be kept during the 

 test under perfectly normal conditions with the possible ex- 

 ception that it is necessary to keep them up in stables rather 

 than to allow them to run in a pasture. Before injection the 

 temperature of the animals should be taken. It is recom- 

 mended that the temperature be taken every two hours for 

 four to six hours preceding the injection of tuberculin. The 

 real purpose of taking these preliminary temperatures is to 

 ascertain whether or not the animals are suffering from any 

 disorder that affects the temperature. It is required by some 

 livestock sanitary boards that a definite number of tempera- 

 tures should be taken before injecting the tuberculin. In 

 practice two preliminary temperatures taken two hours apart 

 before making an injection are quite sufficient. 



3. The tuberculin is administered subcutaneously. It is 

 usually injected under the loose skin in the neck or in the 

 axilla. Care should be taken that the syringe is sterilized. It 

 has been advised that the skin of the cow at the point of in- 

 jection should also be disinfected. This is a safe precaution; 

 but the difficulty of disinfecting the skin quickly and the in- 

 frequency with which cattle become infected with skin organ- 

 isms suggest that this precaution is not necessary. If the 

 syringe is sterilized in the beginning, the method recommended 

 by Dr. Law, to insert the needle in pure (liquid) carbolic acid 

 between each two injections, gives good results. This destroys 

 any organisms that might become attached to the needle in 

 withdrawing it from one animal, and the acid that adheres to 



21 Circular No. 1. N. Y. State Vet. Coll., 1908. 



