270 DISEASES OF CATTLE, SHEEP, GOATS, ETC. 



affected as are the bones, joints and skin. Tuberculosis is also 

 found in the reproductive organs. The udder is affected in about two 

 per cent of tubercular animals. The disease may be located in parts 

 of the body not usually examined, and it may be present in any 

 part; hence, it is very difficult and often impossible to say from 

 an ordinary post-mortem examination that an animal that has re- 

 acted to tuberculin is actually free from the disease and that the 

 tuberculin test is in error. The tissue can sometimes be shown to 

 be tubercular by microscopical examination when no signs are 

 visible to the naked eye. 



What is the Appearance of the Diseased Organs? The word 

 consumption is often applied to tuberculosis and thus many have 

 been led to believe that tubercular organs are shriveled or shrunken 

 in size, i. e., consumed by disease. On the contrary, a tubercular 

 organ, especially in domestic animals, is usually larger, often sev- 

 eral times larger, than normal. The lymph glands especially, be- 

 come enormously enlarged, and if such enlarged glands are in the 

 neck, may often ca^use difficulty in breathing, due to the pressure 

 on the wind pipe. The lungs frequently may be much enlarged, 

 often weighing several times as much as healthy organs. Hard 

 bunches or swellings, are usually present in the diseased organs, 

 and are the cause of the enormous increase in size so often noted. 



What Gives the Disease the Name Tuberculosis? The name 

 is derived from the characteristic bunches or swellings known as 

 tubercles which are invariably found in diseased animals. These 

 tubercles are at first microscopic in size, but due to growth and by 

 fusion of two or more, they may often become several inches in 

 diameter. On the membranes of the body cavities they sometimes 

 appear as pearl-gray nodules, thus giving rise to the name pearl 

 disease. The tubercles attached to these membranes often look 

 like clusters of small grapes. This has caused the term grapes to 

 be sometimes applied to such an appearance. A tuberculous liver 

 generally shows bright yellow spots on the surface and upon cutting 

 tubercular abscesses are revealed. 



What is the Internal Appearance of the Tubercles? The 

 smaller tubercles when cut show a uniform, gray color. As they 

 increase in size, a small, yellow mass which slowly enlarges is de- 

 veloped in the center. The larger tubercles are often filled with 

 creamy, yellow pus. Again they may be hard and gritty, due to 

 the deposition of lime salts. This condition is known as calcifica- 

 tion. \Vhen the blade of a knife is drawn across the cut surface a 

 scratching sound is heard. The appearance is that of yellow, gran- 

 ular material, which often reminds one of corn meal. The Targe 

 cavities filled with pus are usually called tubercular abscesses. They 

 are found in the lungs, liver and lymphatic glands. The material 

 within the tubercle contains the tubercle bacilli. 



How Does the Tuberculous Udder Appear? The healthy 

 udder is uniformly soft, while the tuberculous udder con-tains the 

 hard tubercles, which, when near the surface or when large, can be 

 felt. As the disease progresses, the infected quarter (for the dis- 



