484 ANNUAL REPORT OF THE Off. Doc. 



be left as they are U4itil the education of the farmer in the matter 

 of tuberculosis has been finished. If there are any practicable and 

 reasonable UH^Tsnres by which, figuratively speaking, the flow of 

 tubercle bacilli from tuberculous cows to healthy human beings can 

 be stopped or impeded, they ought to be immediately enforced. 



As soon as the valua])Ie diagnostic properties of tuberculin had 

 been proved by experience, it occurred to a good many people that its 

 assistance ought to be called in in order to exclude tuberculous cows 

 from milking herds. In other words, it was thought that although 

 it might not be practicable to insist upon the application of the 

 tuberculin test to all infected herds, and lo compel the isolation or 

 slaughter of all cattle thus found to be infected, it might still be pos- 

 sible to require that only cows found to be free from the disease by 

 the application of the lest should be kept for milch purposes. I 

 doubt whether anyone who is well acquainted with the circum- 

 stances of the case now believes this practicable. Here, again, the 

 fact that one-third of the cows now giving milk are tuberculous is 

 an insurmountable obstacle. The cost of carrying out the tuber- 

 culin test several times annually in all the milking herds in this 

 country would be cnorm.ous, and the exclusion of all reacting cows 

 from such herds would seriously disorganize cattle breeding as well 

 as milk production. Moreover, to rely blindly on the tuberculin 

 test, and to pronounce the milk of every cow that does not react 

 to it free from tubercle bacilli, would be very unsafe. The test is 

 recognized to be one of great value, but it is not infallible. Rather 

 serious defects in connection with it are: — (1) That for a period after 

 infection — a period that is sometimes very considerable — an animal 

 will not react; (2) that in some advanced cases of tubercnlosis no 

 distinct reaction is obtainable; and (3) that in a considerable pro- 

 portion of cases a second reaction is not obtainable for some days or 

 weeks after the first. It is therefore clear that if we wish to ex- 

 clude the milk of tuberculous cows, or if the object is the more re- 

 stricted one of preventing the sale of milk from tuberculous udders, 

 some system of inspection is necessary. This was the conclusion at 

 which the Second Royal Commislson on Tuberculosis arrived. We 

 have already seen that whatever danger attaches to milk comes 

 mainly from the cows with tuberculosis of the udder, and the public 

 health would be almost entirely safeguarded from this danger if 

 we could exclude such animals from our dairies. Periodic examina- 

 tion by competent inspectors would go a long way to securing this 

 object, but the inspection would require to be at rather short in- 

 tervals, for a tuberculosis of the udder may come into existence and 

 attain most dangerous dimensions in a period of a few weeks. The 

 more froquent the inspection the better, but. of course, this means a 

 great deal of expense. 



