TUBERCULOSIS. 367 



A farmer who has a healthy herd may keep it free from this 

 disease if he will take sufficient precautions along these lines. 

 It has been sometimes asserted that an important source of 

 contagion for cattle is from attendants who are themselves 

 consumptives. It is almost certain, however, that this danger 

 need not be feared, inasmuch as the human tubercle bacillus 

 is only very slightly pathogenic for cattle. 



THE TREATMENT OF AN INFECTED HERD. 



This problem is a far more difficult one and no satisfactory 

 solution has been reached. There seem to be no means yet 

 devised which will eradicate the disease, except the complete 

 destruction of the whole herd and absolute disinfection of the 

 premises. But nevertheless much may be done in the way 

 of reducing the trouble, and, perhaps in some cases, the herd 

 may be perfectly freed. 



The first question which will arise is whether the herd is 

 infected, and then it must be determined which of the animals 

 are diseased and which are still healthy. The method of 

 doing this by clinical symptoms, which has been the only 

 reliance in past years, is wholly insufficient for the farmer who 

 desires to rid his herd of the disease, or reduce it to a mini- 

 mum. Such a method only enables the veterinarian to pick 

 out the worst cases, and it inevitably leaves others in the 

 herd which are sure, in time if not immediately, to scatter the 

 bacilli among the healthy animals. Clinical symptoms pick 

 out only a small part of the animals infected with the disease. 

 Whether or not most of the milder cases are likely to develop 

 into serious ones is not in this connection of much importance, 

 for there is positive evidence that some of them are likely to, 

 and will soon become sources of infection to the herd. Al- 

 though the farmer may feel that many of these animals are 

 still useful, and that they may continue to be legitimately 

 useful for a number of years, no one can fail to recognize that 



