TUBERCULOSIS. 373 



the chief source of danger to the calves is removed if they are 

 brought up on milk of healthy animals or upon milk that has 

 been boiled. These calves must themselves be tested with 

 tuberculin before they are allowed to mingle with the healthy 

 herd. Lastly, the farmer must have the healthy herd tested 

 each year, or, better, each six months, and must always re- 

 move any reacting animals to the other herd. 



Such a method of treatment involves considerable labor and 

 some expense. It is troublesome and certainly will not be 

 adopted by the farmer without strong incentives. Where it 

 has been tried it has resulted in a great reduction in the 

 amount of the disease, and it has been found that a badly in- 

 fected herd may thus, in a few years, be brought into a tolerably 

 good condition. But even at its best it has not proved com- 

 pletely successful, for it has not resulted in a complete eradi- 

 cation of tuberculosis from the herd, and each time the healthy 

 herd has been tested, some animals respond to the test, 

 although in constantly decreasing numbers. But, although 

 only partially successful, it is the only means yet suggested 

 for protecting a farm from the disease after it has once found 

 its way into the herd, except the radical one of complete 

 slaughter of all reacting animals. 



Whether a farmer will adopt such a method will depend 

 upon the extent of his desire to eradicate the disease from his 

 herd. He must remember that, as long as tuberculous animals 

 are allowed to associate with healthy animals, he is running a 

 risk of their being the means of distributing the disease. His 

 only safeguard for his herd is a complete separation of the 

 infected animals from the others. This may be most easily 

 accomplished by slaughtering the infected individuals ; but if 

 they are especially valuable animals or very numerous, such 

 a course would be ruinous. He may allow the infected ani- 

 mals to mingle with the herd, and for a time, perhaps, see no 

 disadvantage ; but he must always remember that he is running 



