384 PERICARDITIS. 



The quantity of liquid also varies within very wide limits. There 

 may be scarcely any exudation. In that case the pericarditis is of a 

 partially adhesive character, with abundant false membranes. As a 

 rule the quantity of fluid exudation varies between seven and eight 

 quarts, but sometimes the quantity is much greater. Trasbot de- 

 scribed an instance in which the united weights of the heart and peri- 

 cardium exceeded 36 lbs. Hamon mentioned a case of pericarditis in 

 which the liquid exudate exceeded twenty quarts. 



When inflammation is first set up the liquid is serous, yellowish, 

 or reddish-yellow. It contains fibrinous Hocculi in suspension. Little 

 by little this exudate becomes purulent, whilst the internal layers of the 

 pericardial serous membrane undergo desquamation. These are next 

 covered with false membranes of varying appearance ; the iibro-albu- 

 minous exudation is wrinkled, villous and tufted. The two layers of 

 serous membrane are connected at certain points by this exudation, the 

 adhesions being sometimes very extensive. The pericardial sac pro- 

 perly so called becomes the seat of marked lardaceous thickening, due 

 to inflammation. The heart appears entirely covered with a layer of 

 greyish or earthy-coloured granulation tissue, which appears as though 

 baked, and was compared by Hamon to the back of a toad. It is atro- 

 phied as a consequence of prolonged compression. 



Under the influence of the excentric pressure of the liquid the peri- 

 cardial sac is distended and comes in contact with the walls of the chest, 

 to which it may adhere. The foreign body, especially if small, is not 

 always easy to find. 



The myocardium often displays interesting lesions. At first there is 

 thickening, or more commonly sclerous degeneration, of the superflcial 

 layers covering the ventricles, and then appears a crop of little miliary 

 abscesses. Abscesses of considerable size have several times been 

 detected in the walls of the ventricles and in the interventricular 

 septum. 



The foreign body, moreover, may not only injure the myocardium, 

 but may even perforate it completely and produce ulcerative endocarditis 

 (Cadeac). In this case infectious germs very rapidly invade the circu- 

 lation and all the tissues, and the animal dies of pyaemia. 



These essential lesions are accompanied by others of varying im- 

 portance. Thus the lung is congested throughout, and by contiguity 

 of tissue inflammation may extend from the pericardium to the lower 

 part of the pulmonary lobes and to the pleura. 



Interference with the return circulation induces lesions due to venous 

 stasis : dropsy of the chief serous membranes, oedema of the connective 

 tissue, pleural and peritoneal exudations, etc. If the hind limbs never 

 become swollen it is because the skin covering them is very resistant 



