MYOCARDITIS 83 



heart muscle leading to inflammation and fatty degeneration. 

 The other organs in the body are often similarly affected 

 during the course of infectious diseases. 



(d) From poisons (arsenic, phosphorous, silver, mercury, 

 etc.) being absorbed, carried through the circulation to the 

 heart muscle, producing irritation, congestion, and some of 

 them (phosphorous, arsenic) later fatty degeneration of the 

 muscle. 



(e) Often results by spread of the inflammation from the 

 endocardium and pericardium, especially in ulcerous endo- 

 carditis and suppurative pericarditis, the infection reaching 

 via blood the heart muscle. 



(/) Direct injuries to the heart which occur quite frequently 

 in small animals from foreign bodies perforating the esoph- 

 agus or chest wall; also by being run over, the heart muscle 

 becoming contused. 



Necropsy. Pathologically numerous conditions are found, 

 the changes in the myocardium are quite varied, and in acute 

 myocarditis may be classed under two heads as follows: 



(a) Acute Parenchymatous Myocarditis. This as a primary 

 condition, is not very common, and is usually associated with 

 acute inflammation in other organs. In this form there is 

 found interstitial infiltration, inflammation of the muscle 

 fibers, which are colored reddish-gray, yellowish-white, or 

 even white. The muscle fibers are indistinct and show a 

 more or less homogeneous structure. 



Microscopically, the fibers show a loss of striation, with 

 small cellular infiltration in the interstitial connective tissue. 

 Large numbers of white corpuscles are found between the 

 fibers. 



(6) Purulent Myocarditis. This form occurs quite com- 

 monly in the dog, less commonly in cats and birds, and is 

 found mostly in pyemic conditions. Small abscesses are dis- 

 tributed through the connective tissue varying in size from a 

 millet seed to a pea. Sometimes by confluence the abscesses 

 are much larger. 



Symptoms. In the early stages the symptoms are similar 

 to those of insufficiency or weakness of the heart. The heart 

 beat is very rapid, three to four times normal, throbbing, and 



