INFECTIOUS DISEASES OF CATTLE. 419 



Similar precautions should be observed in removing the manure of 

 the infected herd from the barnyard and other places accessible to 

 ■ cattle, since it is known that tuberculous cattle frequently eliminate 

 large numbers of tubercle bacilli from their bodies through the feces. 

 The ground under the manure pile could then be disinfected either 

 by applying the above-mentioned formalin solution or unslaked lime 

 thickly sprinkled over the soil. 



If all the animals which react are destroyed and the stables dis- 

 infected in this manner, the herd should remain free from the disease 

 unless other affected animals are added to it. The introduction of 

 the disease in this manner may be avoided by requiring a tuberculin 

 test of all new animals admitted on the premises. 



It is unfortunately a fact that animals with tuberculosis which have 

 been tested several times may become so accustomed to tuberculin 

 that they will no longer react; consequently it is always advisable to 

 purchase cattle from some one who is known to be reliable, as other- 

 wise tubercular animals may be treated with tuberculin for the pur- 

 pose of hiding the disease. 



In the case of very valuable thoroughbred animals it may be more 

 advantageous to retain the reacting animals which are in good con- 

 dition, in order to breed from them, and in that manner avoid the 

 excessive loss which would follow from their immediate slaughter. 

 This may be done safely if proper precautions are adopted. The 

 healthy animals should be separated from the diseased ones, and the 

 stable in which the diseased animals have been should be frequently 

 disinfected. When calves are dropped by the tubercular cows they 

 should be immediately removed, or at least not allowed to drink the 

 mother's milk more than once or twice, and after that fed upon the 

 milk of healthy cows. The milk from the animals which have reacted 

 should not be used until after it has been boiled and the tubercle 

 bacilli thus destroyed. The young animals which are raised from 

 tubercular dams should be tested when they are about six months 

 old, and all of those which react should be immediately slaughtered. 

 It has been found that by following the plan suggested above not 

 more than 1 or 2 per cent of the calves will develop tuberculosis. It 

 is of course some trouble to follow this method, but it enables the 

 owner of a purebred herd to retain the strains of blood which ha has 

 been breeding and gradually to eliminate the disease. At the end of 

 six or eight years he should have a herd of cattle free from tubercu- 

 losis and be prepared to destroy all of those which have reacted. 



BOVINE TUBERCULOSIS AND THE PUBLIC HEALTH. 



The increasing amount of evidence pointing to the identity of 

 human and animal tuberculosis, combined with the extraordinary 



