1070 Mywarditis. 



cle^'elop!s upon the basis of an intinenzal infection. Since in 

 infections diseases the heart mnscle behaves like a parenchyma- 

 tous organ, the frequency of myocarditis in infections diseases 

 may best be indicated by the comparatively frequent occurrence 

 of renal albuminuria, whioh points to a parenchymatous disease 

 of the kidney. 



Of poisons, especially the heavy metals (mercury, copper, 

 antimony), also phosphorus and arsenic are capable of causing 

 a degeneration of the heart muscle. 



Myocarditis, usually purulent in character, develops if 

 infected emboli have been carried into the blood vessels of 

 the heart (myocarditis embolica), which occurs most frequently 

 in cattle. The emboli may be derived from any part of the 

 body where suppuration or gangrenous disintegration of tissues 

 is present, but most frequently a purulent or gangrenous in- 

 Ilanunation of the lungs or of the intestinal tract, a disintegrat- 

 ing thrombus of the umbilical vessels, purulent inflammation 

 of the hoof, puerperal endometritis, strangles, glanders or 

 decubital gangrene are responsible for the affection. In cattle 

 the necrosis bacillus sometimes gives rise to the formation 

 of dry necrotic foci in the heart muscle (Kitt). 



There is also a possibility in the case of ulcerating valvular 

 inflammation that portions of the blood clots deposited upon 

 the valves together with pathogenic bacteria are arrested in 

 the smaller branches of the coronary arteries. The transpor- 

 tation of bacteria into the blood vessels of the valves and into 

 those of the heart muscle are probably simultaneous (see 

 endocarditis), but the inflammation may be continued directly 

 from the diseased valves to the heart muscle. The same is 

 sometimes the case in purulent or ichorous pericarditis. 



Injuries of the heart muscle produce a purulent or ichorous 

 myocarditis most frequently in cattle and in the same manner 

 as the inflammation of the pericardium which has usually 

 developed earlier from the same cause (see p. 1040). It is 

 much less frequent that foreign bodies which have penetrated 

 the wall of the thorax and have entered the heart produce 

 myocarditis, because such injuries usually cause death even 

 before an inflammatory process could possibly be developed. 



Anatomical Changes. A very variable number of muscular 

 fibers is finely granular, swollen, and they sometimes contain 

 fat globules. If the disease is extensive the muscular fibers 

 disintegrate into larger or smaller clumps (Zschokke). The 

 interstitial tissue frequently shows serous-cellular infiltration 

 and sometimes contains red blood cells (Myocarditis parenchym-, 

 atosa). The heart muscle is of a lighter brown-red than normal, 

 or grayish-red. It is flabby and friable. The cut surface con- 

 tains light gray or even butter-yellow dots and stripes (which 

 are especially noticeable in animals dead of foot and mouth 

 disease), sometimes also dark red dots. In the case of more 



