CttROKlC PERICARDITIS. 



389 



is of little importance, because the opening is inclined downwards, 

 and also because it is impossible to hope for aseptic healing. 



The dressing is renewed after forty-eight hours, and every three or 

 four days afterwards. 



The cedematous infiltration about the front portion of the body 

 disappears rapidly in two to three days, and should the animal be 

 slaughtered the meat is quite sound in appearance. 



This operation does not aim at effecting a cure, but is simply for the 

 purpose of allowing animals which would otherwise be valueless to be 

 slaughtered and sold. 



CHRONIC PERICARDITIS. 



Pericarditis when due to tuberculosis may assume the chronic form. 

 Tuberculous pericarditis, at least in a large number of cases, is only accom- 



FiG. ISO. — Photograph of the same subject as Fig. 179, taken six claj's later. 



panied by slight exudation, which might remain unnoticed unless the 

 animals were carefully examined; but it causes the internal surface of the 

 pericardial sac and the surface of the myocardium to become covered 

 with exuberant vascular growths, which by setting up adhesions lead to 

 partial or generalised union of the heart and pericardial sac. Between 

 these adhesions, which form partitions, are found little cavities filled 

 with sero-sanguinolent, grumous, or caseous liquid. In time the ad- 

 hesions increase in number, pericarditis obliterates the free space, and 

 the heart becomes wholly adherent to the pericardium. 



As in acute pericarditis, the fibrous layer undergoes thickening and 

 hardening processes. The superficial layers of the myocardium undergo 

 sclerous transformation, and the tissues forming the adhesions them- 

 selves may assume the characters of fibrous tissue. 



