398 CHRONIC .INFECTIOUS DISEASES 



Acute Miliary Tuberculosis. — This form of tuberculosis is 

 usually seen to accompany a primary lesion from which it 

 sprang by way of thrombosis or direct eruption into a blood- 

 vessel. Not infrequently, in the same lung, along the course 

 of a bronchus is found a large, irregular-shaped caseous or 

 calcified primary focus, and throughout the rest of the 

 lung tissue, a number of small, round tubercles all of about 

 the same size and alike caseous (secondary foci). These 

 tubercles are usually evenly distributed, and each surrounded 

 by a red zone. In the liver, spleen and kidneys similar lesions 

 may be present. The corresponding lymph glands in miliary 

 tuberculosis are always acutely swollen and"* their cortical 

 substance abnormally reddened. 



Symptoms. — Fully 90 per cent, of the cases of tuberculosis 

 in animals present no clinical symptoms. As long as the 

 disease is local and does not seriously involve the gastro- 

 intestinal tract, or if there is no general intoxication of the 

 organism with the toxins of secondary infection, a remarkable 

 destruction of parenchymatous organs may follow and the 

 patient appear healthy. In generalized tuberculosis or, as 

 noted, if the bowels are much involved, or sapremia is attend- 

 ing, symptoms develop. The character of the symptoms is, 

 however, so indefinite that they cannot be relied upon with 

 any degree of certainty. Any of them may be caused by 

 other diseases and none are pathognomonic of tubercu- 

 losis. 



Fever. — The temperature of the body in tuberculosis is 

 usually not disturbed until the late stages of the disease, when 

 fever of an intermittent or remittent type sets in. Sometimes 

 the temperature is higher in the morning than in the evening. 

 -As a rule, following a period of fever, there may be several 

 weeks of normal temperature. Only in the last stages is the 

 fever of a continuous type. As the symptoms of tubercu- 

 losis vary in the different domesticated animals, each kind of 

 animal will be considered separately as follows : 



Ox. — The period of incubation after artificial infection in 

 bovine tuberculosis is two weeks or more. Following natural 

 infection it is probably much longer. As a rule months or 

 years elapse before appreciable symptoms appear. In cattle 



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