Tuberculosis. 117 



has an injurious effect on bacteria, destroying them 

 within a few moments when they are directly exposed 

 to it. It has been shown by direct experiment that the 

 disease will spread more rapidly in unsanitary barns, 

 than in those which are well lighted and ventilated. The 

 use of whitewash twice a year is advisable as it has a 

 disinfecting action and makes the stable lighter. 



Symptoms of the disease. In the early stages there 

 are no definite symptoms. The disease starts in some 

 part of the body, usually in the lymph glands, and may 

 make headway very slowly. For years it may be con- 

 fined to a single gland, ,but sooner or later on account 

 of some condition that may temporarily impair the re- 

 sistance of the animal, such as calving, the disease 

 develops more rapidly. In the last stages the animal 

 becomes emaciated, the hair is rough, the eyes sunken, 

 the head extended; the appetite may be good, but the 

 food apparently has no effect. If the lungs are in- 

 volved the animal may cough, especially when forced to 

 move rapidly after resting. If there are hard painless 

 swellings in the region of the throat or shoulders, the 

 animal may be suspected of tuberculosis. If there are 

 hard nodules in the udder; if one or more quarters are 

 enlarged and hard, but painless and cold, or if the 

 lymph glands at the top and rear of the hind quarters 

 of the udder are enlarged, suspicion may be aroused. 

 It is absolutely impossible for the most experienced 

 veterinarian, in the great majority of cases, to tell from 

 a physical examination alone, whether the animal has 

 tuberculosis or not, or predict the stage of the disease. 

 An animal may be the picture of health and be as great 

 a source of danger as one in the last stages. 



