HISTOLOGY 



341 



The agglomeration of tubercular glands form irregular and nodular 

 hard, not painful masses up to the size of a fist. Later they become 

 softened, fluctuation followed by ulceration appears, and the fistulous 

 tracts formed discharge a purulent, caseous secretion. The intestines 

 show infiltrations, nodule formation, and ulceration. Tuberculosis of 

 the liver and spleen is common in hogs; the bones and the muscles 

 become secondarily involved. The lungs, the pleura, and the peri- 

 toneum generally show the form of a miliary tuberculosis. Tuber- 

 culosis of the central nervous system occurs, but it is rare. Acute 

 miliary tuberculosis also occurs in the hog, and is rapidly fatal. 



FIG. 151 



Transverse section through the spinal cord of a hog suffering from tubercular cerebrospinal 

 meningitis. (Preparation by Dr. L. E. Day.) 



Histology. Stewart and Kinsley, who have studied the histology of 

 the tubercle in hogs, found that there are two general types. One 

 type is represented by the cellular necrotic and calcified necrotic 

 tubercle. "This group of tubercular lesions is probably the result of the 

 activity of quite virulent tubercle bacilli. The second type of lesions 

 are those described as fibrous tubercles, which may be preceded by 

 cellular tubercles and usually contain calcareous foci in the later 

 stages; these lesions are no doubt the result of infection with slightly 

 virulent tubercle bacilli. In the examination of 770 sections no giant 

 cells were seen, and it is, therefore, believed that the tissue reaction in 

 hogs against infection with the tubercle bacillus does not favor the 

 production of giant cells." 



