446 CHRONIC INFECTIOUS DISEASES 



tuberculin test, (b) Secondary to this is to promote a high 

 resistance to disease in the individuals constituting the 

 herd. This may be accomplished by proper breeding, 

 feeding, good sanitary surroundings and an outdoor life. 

 It would be still safer once yearly to test the herd with 

 tuberculin. 



Eradication. — ^Tuberculosis is a. disease which is spread 

 practically only by infected individuals. To remove these 

 individuals is to remove the soiurce of infection. While it is 

 true that not all tubercular animals are at all times passing 

 tubercle bacilli and thus spreading infection, in practice 

 any attempt to differentiate in favor of one case of the disease 

 as against another (to determine whether "open" or "closed", 

 is not feasible. A tubercular ox is a menace and constant 

 source of danger to the rest of the herd. It should, therefore, 

 be removed from all contact, direct or indirect, with its 

 susceptible companions. 



Generally speaking, there are two methods of eradicating 

 the disease in cattle, both of which are based upon the 

 permanent separation of the diseased from the healthy. 



A. Radical Method. — Commonly used in the United 

 States, and where the disease has made limited progress. 

 This method consists in testing the entire herd with tuber- 

 culin and killing the reacting animals either on the premises, 

 where the carcasses are rendered innocuous, or preferably 

 in a central slaughter house, in which the carcasses are 

 passed upon in regard to whether or not fit for food by 

 competent veterinary inspectors. Subsequently the premises 

 (stables, barns, etc.) are thoroughly cleaned and disinfected. 

 This method is certain in its results but not always applicable. 

 It does away with the necessity of keeping two herds (react- 

 ing and healthy), and the rearing of the calves is not so 

 cumbersome as with the palliative methods. 



B. Palliative Methods. — (a) The Bang method. Where the 

 number of animals in a given herd is too great, or it is the 

 desire to preserve valuable blood lines, a less drastic method, 

 of control has been suggested. It is as follows: All clinical 

 cases of tuberculosis (lung, bowel, uterus, udder) are taken 

 out of the herd and destroyed. Reacting cattle which show 

 no clinical evidences of the disease are kept separated from 



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