420 DISEASES OF CATTLE. 



only of injecting the tuberculin but also of interpreting the results, 

 and particularly of picking out all clinical cases by physical exami- 

 nation. The latter observation is extremely important and should 

 always be made on every animal tested. 



In the second class, where the temperature test is used, errors are 

 avoided by eliminating from the test those cases that are nearing 

 parturition or are in heat or show evidence of the previously men- 

 tioned diseases or exhibit temperatures sufficiently high to make them 

 unreliable for use as normal. "\Miere other methods of test are used 

 these conditions do not have an important bearing on the results. In 

 addition, a satisfactory tuberculin must be used: also an accurate 

 thermometer and a reliable syringe, in order that a sufficient dose of 

 tuberculin may be given. Finally, the number of apparent errors of 

 the tuberculin test will be greatly diminished if a careful post- 

 mortem examination is made, giving especial attention to the lymph 

 glands. This low percentage of failures being the case, cattle owners 

 should welcome the tuberculin test, not only for their own interest 

 but for the welfare of the public as well. Where this method of 

 diagnosing the disease has been adopted tuberculosis is gradually 

 being eradicated. Without its use the disease can not be controlled 

 and the owner is confronted with serious and continuous losses; with 

 its use the disease can be eradicated from the herd, a clean herd 

 established in a few years without very serious loss or hardship, and 

 the danger of its spread to man removed. Tuberculin may therefore 

 be considered a most beneficial discovery for the stock raiser. 



Law has clearly stated the question when he says — 



Many stock owners still entertain an ignorant and unwarranted dread of the 

 tuberculin test. It is true that when recklessly used by ignorant and careless 

 people it may be made a root of evil, yet as employed by the intelligent and 

 careful expert it is not only perfectly safe, but it is the only known means of 

 ascertaining approximately the actual number affected in a given herd. In 

 most infected herds living under what are in other respects good hygienic condi- 

 tions two-thirds or three-fourths are not to be detected without its aid, so that 

 in clearing a herd from tuberculosis and placing both herd and products above 

 suspicion the test becomes essential. * * * in skilled hands the tubercu- 

 lin test will show at least nine-tenths of all cases of tuberculosis when other 

 methods of diagnosis will not detect one-tenth. 



Probably the most pox:)ular objection to tuberculin is that it is too 

 searching, since it discovers cases in which the lesions are small and 

 obscure. ^Yhi\e this fact is admitted, it should also be remembered 

 tliat such a small lesion to-day may break down and become widely 

 disseminated in a relatively short period. Therefore any cow 

 affected with tuberculosis, even to a slight degree, must be considered 

 as dangerous not only to the other animals in the herd but also to 

 the consumer of her products. 



In 1898 Bang, of Copenhagen, one of the highest European 

 authorities, in his paper presented to the Congress for the Study 

 of Human and Animal Tuberculosis, at Paris, said : 



