702 



Infectious diseases. 



limb bones are attacked as a rule only in the vicinity of diseased 

 articulations. 



The vertebral lesions corresponding to those in Pott's disease in 

 human beings are very difficult to discover before they produce com- 

 plications, such as depression of the spine, compression of the spinal 

 cord, paralysis, etc. 



Lesions of the bones of the head or of the limbs are charac- 

 terised by local deformity, destruction of osseus tissue, invasion of 

 surrounding tissues, and by local symptoms peculiar to tumours 

 originating in the periosteum. 



Tuberculosis of joints produces special symptoms resembling those 

 seen in the " white swellings " of man, that is, diffuse, cedematous, 



warm and moderately 

 painful swelling of 

 adjacent parts, ac- 

 companied by lame- 

 ness of varying in- 

 tensity. According to 

 Guillebeau and Hess, 

 many conditions de- 

 scribed as strain or 

 rheumatic arthritis 

 are really tuberculous 

 in character. They 

 may remain station- 

 ary for a long time, 

 or even recede under 

 treatment. As a rule, 

 however, these forms 

 of tuberculous arthritis assume the fungoid type and prove incurable. 

 They are clinically distinguished from ordinary arthritis by the 

 enormous swelling, which involves the extremities and a portion of 

 the shafts of the bones. The adjacent muscles are chronically con- 

 tracted, and the diseased joint is held semi-flexed. In course of time, 

 if the patients are kept alive, abscess formation may occur, but this 

 is seldom seen in practice, because the animals are slaughtered. 



Fict. 280. — Perforating tuberculosis of the right 

 frontal region. 



TUBERCULOSIS OF THE BRAIN. 



Tuberculosis of the nervous centres, localised either in the meninges 

 or the brain proper, may attack both young and old animals, not as a 

 primary condition, but as a sequel to visceral disease, which, however, 

 may have produced no outward indications, a fact that renders the 

 diagnosis extremely difficult. 



