232 CLINICAL DIAGNOSTICS. 



Dose.* The tuberculin prepared as above described is 

 diluted with 9 volumes of water to which y^fo of carbolic 

 acid has been added. Cattle and horses receive 5 cc of this 

 solution, yearlings 2.5 cc, calves 1 cc and dogs 0.5 — lcc. 



Technique. The tuberculin is injected subcutane- 

 ously at the neck or in front of the shoulder. Before and 

 after using, the hypodermic syringe should be disinfected with 

 a 2% solution of carbolic acid. Before inserting the hypo- 

 dermic needle smooth down the hair at the point of injection. 

 Disinfection of the injected area is not necessary if care is 

 exercised otherwise. The best time for injection is in the 

 evening between 9 and 10 o'clock. The bodily temperature of 

 the animal to be injected should have been ascertained at noon 

 of the day of injection and also just before injection. Eight 

 or nine hours after injection of the tuberculin, hence at 6 A. 

 M., next day, the temperature of each animal should again be 

 taken, and thereafter every two hours until the 18th hour 

 after injection. Perhaps it is unnecessary to state that the 

 temperatures should be recorded. 



Interpretation of Results. In tuberculous animals the 

 injection of tuberculin produces fever (reaction), healthy an- 

 imals are not affected. 



a. Cattle with pre-injection temperatures not exceeding 

 39.5° C. [103.1° F.'J and post-injection temperatures exceed- 

 ing 39.5° C. [103.1° F.], providing the difference between 

 the highest pre-injection temperature and the highest post-in- 

 jection temperature is at least 1" C. [1.8° F.] are regarded as 

 tuberculous. 



b. In calves under 6 months of age a rise of temperature 

 exceeding 40° C. (104° F.) after injection of the tuberculin. 



f*This applies, of course, to the German tuberculin. In America the article is man- 

 ufactured by a number of reliable firms. It should always be used as fresh as possible 

 and the dose regulated according to the strength of the material. This is always indi- 

 cated in the "directions for use."] 



