INFECTIOUS DISEASES OF CATTLE. 413 



tuberculin test, but as the most dangerous of these may be picked 

 out by ordinary clinical examination this fault of tuberculin is not 

 so serious as it at first sight appears. This being the case, it should 

 not be necessary to force the tuberculin test upon owners. They 

 should be anxious to adopt it in their own interests and for the pro- 

 tection of their patrons. There is to-day no greater danger to the 

 cattle and hog industries than that which confronts them in the form 

 of tuberculosis, a disease already widespread and rapidly extending. 

 Furthermore, tuberculin must be considered as harmless for healthy 

 animals in view of the results revealed by numerous tests covering 

 vast numbers of animals. And it has also been clearly demonstrated 

 that tuberculin interferes in no way with the milking function in 

 healthy cattle ; neither in the quantity of milk nor , in butterf at 

 value has any variation been detected. The conclusions of some of 

 the best authorities on the subject of its harmlessness to healthy 

 animals are given below. 



Nocard and Leclainche state : 



Direct experiments and observations collected by thousands show that the 

 tuberculin injections have no unfavorable effect. With healthy animals the sys- 

 tem is indifferent to the inoculation; with tuberculous animals it causes slight 

 changes which are not at all serious. 



Bang has written as follows on this question : 



We will now consider the following question, a very important one, in the appli- 

 cation of tuberculin, viz: Can the reaction produce a worse condition in tubercu- 

 lous animals than before existed ? Hess emphatically states that it can , and on this 

 account he earnestly warns against its application. My attention has been directed 

 to this question from the beginning. In my first publication on tuberculin injec- 

 tion I reported two cases in which acute miliary tuberculosis wa3 proved in two 

 high-grade tuberculous cows several weeks after the tuberculin injection. I then 

 stated my suspicion that perhaps the tuberculin injection had some connection 

 with this, just as is often supposed to be the case in human practice. With my 

 present very large amount of material for observation at hand I may express the 

 following opinion: Such an acute development of tuberculosis as a result of tuber- 

 culin injection is to be feared only exceptionally, and then in cases of advanced 

 tuberculosis. It must not be forgotten that acute miliary tuberculosis by no means 

 rarely accompanies an advanced tuberculosis of long standing. It is therefore 

 impossible to offer strict proof of the causal connection with the injection, and only 

 oft-repeated observation could make this probable. In support of my view I offer 

 tha following: In the course of the last three years I have made careful post- 

 mortem examinations of 83 tuberculous animals, which have been removed from 

 my experiment farm, Thurebylille. Among these were 18 (or, strictly speaking, 

 23) high-grade tuberculous aniraals. I have been able to prove miliary tuberculosis 

 in only 4 of these. Among the others, which showed less developed tuberculosis, 

 I have never found miliary tuberculosis, and with very many I have never found 

 any sign of a more rapid development of the process. On the contrary, it has 

 been proved that the disease was restricted locally, often for years, in spite of 

 yearly repeated injections. Dissections were made at very different periods after 

 the injections— in 17 cases from four to twelve days after the last test. In all of 



