TUBERCULIN TEST 



217 



nervous chill. Why we get this reaction* is not positively 

 determined. 



Applying the tuberculin test. In brief, the method for 

 applying the tuberculin test in cattle is as follows : 



1. The normal temperature of the animal to be tested 

 must be determined. It is recommended that it be taken 

 hourly or ever}' two hours for the day preceding the test. In 

 practice veterinarians usually take the temperature but once 

 or twice before injecting the tuberculin. 



2. The tuberculin is injected subcutaneously in the side 

 of the neck. Care must be taken that the syringe is sterile 

 and the site of injection should be disinfected. The size of the 

 dose depends upon the preparation of tuberculin, that is, the 

 degree of concentration. 



*Trudeau {Johns Hopkins Hospital Bulletin, }u\y , 1899) gives the 

 following summary of the mechanism of the tuberculin reaction. "The 

 most generally accepted theory at present in regard to it is, briefly, the 

 «mall dose of tuberculin injected is a partly specific irritant both to 

 tuberculous foci and to the susceptible organism in general. It pro- 

 duces intense hyperemia of all tuberculous tissue in the body (local 

 reaction), and as the result of this hyperemia much toxin stored up in 

 the tubercles themselves is thrown into the general circulation and pro- 

 duces fever and characteristic symptoms which go to make up what is 

 termed 'a general, reaction.' That these poisons stirred up in the tuber- 

 cles are in part at least derived from the dead or weakened bacilli has 

 been shown by the experiments of Babes and Proca, who found that if 

 two sets of rabbits be injected with equal quantities of living and dead 

 bacilli, the latter react to the tuberculin test at a much earlier period 

 than those inoculated with living germs. This hypothesis that the gen- 

 eral reaction is brought about by toxins already stored up in the tuber- 

 culous lesions and exploded as it were by the hyperemia produced 

 about these lesions as the result of the test of injection of tuberculin, is 

 borne out by the fact that a greater amount of albumose can be recov- 

 ered from the evaporated urine collected during the reaction than was 

 contained in the test injection also by clinical observations which indi- 

 cate that patients suffering from localized surgical tuberculous processes 

 of limited extent, and where the vascular supply to the part is limited, 

 required a larger test injection to produce the reaction than those who 

 have extensive or scattered visceral lesions in highly vascular organs 

 like the lungs." The reader is referred to this paper for a careful con- 

 sideration of the vexed questions relating to tuberculin. 



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