TUBERCULIN REACTION 641 



TUBERCULIN REACTIONS AMONG THE LOWER ANIMALS 



In veterinary practice tuberculin is used almost solely for diagnostic 

 and only occasionally for therapeutic purposes. 



Four reactions are in common use : 

 The Subcutaneous Test. 

 The Conjunctival Test. 

 The Cutaneous Test. 

 The Intracutaneous Test. 



The technic for conducting these tests and the reactions secured are 

 quite similar to those just described, and I would refer the veterinary 

 surgeon to these respective descriptions. Differences in technic are 

 confined principally to dosage. 



The Subcutaneous Tuberculin Test. This is conducted with Koch's 

 old tuberculin. The method of preparation is given in the succeeding 

 chapter, under Tuberculin Therapy. Concentrated tuberculin is pre- 

 pared by concentrating the bouillon nitrate to one-tenth its original 

 volume. Diluted tuberculin is the concentrated product diluted to its 

 original volume by mixing 1 part of the dilution with 9 parts of 0.5 to 1 

 per cent, phenol in sterile normal salt solution or distilled water. 



The injections are always given subcutaneously hi some convenient 

 area, preferably around the shoulder, which has been shaven and cleaned 

 beforehand with a solution of creolin. 



The first dose for horses and cattle is usually 0.4 c.c. of concentrated 

 or 4 c.c. of diluted tuberculin; the second dose is usually 0.8 c.c. of con- 

 centrated or 9 c.c. of the diluted tuberculin. 



The general local and focal reactions are similar to those previously 

 described. 



The Conjunctival Tuberculin Test. For this test Koch's concen- 

 trated tuberculin may be used. Preference is usually given to the puri- 

 fied product, prepared as follows: Mix one part of Koch's concentrated 

 tuberculin with 20 parts of absolute alcohol. The precipitate that forms 

 is filtered off and dried over sulphuric acid. This powder is then made 

 up into a 4 per cent, and 8 per cent, solution in sterile distilled water. 



Two or three drops of the 4 per cent, dilution are placed in the inner 

 canthus of one eye, to sensitize the tissues. After twenty-four hours, 

 unless a positive reaction is present, two or three drops of the 8 per 

 cent, solution are instilled in the same eye in the same manner. The 

 reaction is usually apparent in from six to twelve hours (Fig. 128). 



For the types of reaction and precautions to be observed see the 

 previous description. 



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