280 AGRICULTURAL BACTERIOLOGY 



Fi. 47. A Tubercular Animal 



The animal skewed no physical symptoms although it was eliminating the 

 disease-producing organisms and was thus serving to infect the remainder of 



the herd 



from a physical examination alone whether an animal has 

 tuberculosis or not, or to determine the stage of the disease. 

 An animal may be apparently in perfect health, and yet be 

 dangerous to other animals because of the elimination of 

 tubercle bacilli. 



Many of the open cases can be detected on physical exami- 

 nation by veterinarians highly trained in physical diagnosis, 

 especially when aided by a microscopic examination of the 

 excretions. The physical diagnosis and detection of the 

 open cases form the basis of the Ostertag method of elimi- 

 nating the disease, as practised in Germany. This is ap- 

 plied especially where the percentage. of diseased animals 

 is so high that the removal of the tubercular animals be- 

 comes an economic impossibility. The method has not been 



