BOVINE TUBERCULOSIS. 



151 



disposing conditions undoubtedly have much to do with the de- 

 velopment of this disease ; for instance, close confinement, lack 

 of ventilation and sunshine, injudicious inbreeding' and inherited 

 susceptibility. 



Modes of entrance. — (i) Lungs, with inhaled air; (2) 

 stomach and intestines, with food and drink; (3) by inoculation 

 through broken skin or mucous membrane: (4) by infection in 

 iitcro, i. e., before birth. This (4) is very rare and probably of 

 small importance compared with the others. 



FIG. 57. BOVINE TUBERCULOSIS. (M. H. R.) 

 A case showing plain symptoms of disease. Rare type. 



Structures affected. — Tuberculosis may aflfect any tissue or 

 organ of the body. ]\lilk from tuberculous cows may be tubercu- 

 lous, but the danger is especially great when the udders are af- 

 fected. 



Extent of tissue diseased may vary from a few small lym- 

 phatic glands to a general invasion of lungs, liver, kidneys, mesen- 

 teric glands, peritoneum and pleura. 



Symptoms. — These vary according to extent and location of 

 the disease. A few cases become thin and rough in appearance, 

 and have chronic cough or chronic diarrhoea and show that they 



