INFECTIOUS DISEASES OF CATTLE. 427 



the disease has been adopted tuberculosis is gradually being eradi- 

 cated, while it is spreading rapidly and becoming widely dissemi- 

 nated in those districts where the tuberculin test has not been 

 employed. Without its use the disease can not be controlled and 

 the cattle 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 j-ears 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. 

 Strange to say, many of these men have been incredulous, antago- 

 nistic, or prejudiced against the tuberculin test by misinterpreting 

 published statements, by incorrect, unsubstantiated, or exaggerated 

 reports, and by alleged injurious effects to healthy cattle. 

 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 ij^iorant 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 conditions 

 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 tuberculin 

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

 methods of diagnosis will not detect one-tenth. 



It is perfectly natural that there .should be objection to its use 

 among those who are not acquainted with its method of preparation 

 or its properties, but it is difficult to explain the antagonism of farm- 

 ers who are familiar with the facts connected with the manufacture 

 and use of tuberculin. Probably the most popular objection to tuber- 

 culin is that it is too searching, since it discovers cases in which the 

 lesions are small and obscure. \Aliile this fact is admitted, it should 

 also be borne in mind that such a small lesion to-day may break down 

 and become widely disseminated in a relatively short period. There- 

 fore any cow affected with tuberculosis even to a slight degree must 

 l)e 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 author- 

 ities, in his paper presented to the Congress for the Study of Human 

 and Animal Tuberculosis, at Paris, said : 



Numerous tests made in almost every civilized country have demonstrated 

 that in the majority of cases tuberculin is an excellent means for diagnosing 

 the existence or the nonexistence of the disease, but giving us no positive infor- 

 mation as to the extent to which the disease has progressed. When tuberculin 

 produces a typical reaction we may be almost sure that there exists in the body 

 of the animal a tubercular process. The cases in which a careful examiner has 

 not succeeded in finding it are very rare, and I am led to believe that when, 



