FIFTIETH ANNUAL CONVENTION 121 



ease is of recent origin or if a slightly diseased area has been 

 encapsulated or closed up, it is often very difficult to find 

 evidence of the disease. Lesions in advanced cases gener- 

 ally appear as nodules or lumps, which are tubercles form- 

 ed as a result of the disease. These lumps may be found in 

 great numbers in the lungs and abdominal organs. The 

 lesions are of various sizes and may contain pus, either soft 

 or hard; many times it is gritty. Tubercles are often found 

 in various numbers attached to the walls of the thoracic and 

 abdominal cavities. Lesions of the disease also occur in 

 the lungs, liver, and spleen. The lymph glands, to some ex- 

 tent, are usually affected, and, when cut into, show diseased 

 areas characteristic of tuberculosis. 



Lesions of the disease may be found also in the skin 

 and in or on the bones. In animals only slightly diseased, 

 the lesion may be hidden so that it is impossible for even the 

 most skilful person in post-mortem work to find it. A mi- 

 croscopic examination of the lymphatic glands or other 

 tissues often reveals the presence of tubercle bacilli when 

 no lesion can be seen by the naked eye, a condition show- 

 ing that the disease is just starting. When animals have 

 reacted to the tuberculin test, a very careful post-mortem 

 examination should be made. The action of tuberculin is 

 often discredited when on post-mortem the lesions are not 

 plainly seen, but experience of many years has shown that 

 very few animals reacting to the test were not affected with 

 tuberculosis to some extent even though some were very 

 slight. 



Methods of Eradication. 



Cattle owners who do not know whether tuberculosis 

 exists among their animals should ascertain the fact by 

 having them tuberculin-tested and physically examined by 

 a qualified veterinarian. In many cases thousands of dol- 

 lars and very valuable breeding animals might have been 

 saved by taking up tuberculosis-eradication work in time. 

 Three main projects comprise the general campaign of erad- 

 ication, as follows: 



1. Eradication of tuberculosis from pure-bred herds 

 of cattle. 



