THE PROTECTION OF THE HERD. 275 



This does away with most of the danger to the public consuming the 

 milk, but does nothing toward eradicating the disease from the herd. 



2. All animals that have the disease as shown by clinical or 

 tuberculin test may be slaughtered. The attempt to enforce by 

 law such a treatment of the disease has failed wherever tried. It 

 involves too great a loss and dooms to slaughter many animals in the 

 incipient stages of the disease that might recover and are still 

 useful animals. It is sometimes done voluntarily by private owners 

 in their determination to keep a herd free from the disease. It 

 protects the herd and the public at the same time. 



3. The great losses that are frequently involved in the slaughter 

 of all reacting animals have led to the adoption of other plans for 

 freeing the herd of the disease without such sacrifices. A plan 

 was devised some fifteen years ago by Bang, consisting of separating 

 the reacting animals from the others. The first step is to detect by 

 tuberculin all tuberculous animals. The advanced cases are slaugh- 

 tered. The other reacting animals are separated from the others 

 and placed by themselves, removed from every possible contact 

 with the rest of the animals in the herd. This is not because all 

 reacting animals are necessarily sources of danger, but simply 

 because there is no means of determining when any one of them 

 may become a source of danger to the animals about it. The healthy 

 (non-reacting) animals are then placed by themselves, either in a 

 new barn or the old one after it is thoroughly disinfected. By 

 this means a practical isolation is accomplished. 



If the farmer wishes to preserve the healthy herd from future 

 attack, he must take precautions to have the isolation thorough. 

 It may be effected by simply building a partition in his cattle shed; 

 but in this case there should be no door in the partition, for that 

 would surely result in a carrying of bacilli from one compartment 

 to the other. The farmer should remember the facts already 

 pointed out as to the methods of distributing bacilli. If possible, 

 he should have separate attendants for the two herds, and at all 

 events, the boots worn in attendance on the infected herd should 

 not be worn in the shed occupied by the healthy animals. He 

 must remove all calves from the infected herd a few days after birth 



