180 CLINICAL BACTERIOLOGY AND 



tincture of iodine well rubbed into the skin ; and a dose 

 of from 2 to 3 c.c, according to size and age of animal, of 

 tuberculin injected. The temperature should be taken 

 at least once before injection, and on the ninth, twelfth, 

 fifteenth, and eighteenth hours after injection. 



The animal should be comfortably housed, moderately 

 fed, and in cold weather allowed chilled water only to 

 drink. Animals in season, in advanced pregnancy, or when 

 suffering from other diseases, or with high temperatures, 

 should not be tested until these conditions disappear. It 

 must be remembered, in estimating reactions, that young 

 animals have a slightly higher normal temperature than 

 adults. When the temperature rises 2" 7° F. above the 

 average pre-injection temperature, particularly if the rise 

 should go beyond 103*3° F. on the index, one may safely 

 conclude the animal is tuberculous. 



In very advanced cases of generalized tuberculosis, one 

 may obtain no reaction whatever to the test; but the 

 appearance clinically of such cases should arouse grave 

 suspicions in the mind of the clinician, which, with a know- 

 ledge of the above fact, will prevent him falling into the 

 " no reaction, no tuberculosis " fallacy. On the other hand, 

 an animal may give a diagnostic reaction, and on post- 

 mortem reveal no macroscopical indication of tubercular 

 lesions. Such cases require very careful and systematic 

 investigation, for the infective centre may be so very small 

 as to escape notice. The various organs may be apparently 

 healthy, and a small gland or chain of glands harbour the 

 disease in its mildest form. It is cases such as these that 

 bring the test into bad repute, when, owing to a superficial 

 examination, an infective centre, due to its smallness, is 

 perhaps overlooked. 



When an animal shows a persistent high temperature, 

 one must wait for it to fall before the tuberculin may be 

 used. An animal which has been injected with tuberculin, 

 and reacts, ought not to be injected again for at least a 

 month ; for until the full effects of the first injection have 



