DEGENERATIVE CHANGES OF THE HEART. 195 



These two conditions may occur together, and are not un- 

 frequently associated with other abnormal conditions of the 

 heart, as partial or general dilatation. 



Fatty Infiltration. — In health there is a certain quantity 

 of fat covering the surface of the heart, beneath the visceral 

 layer of the pericardium. Under certain circumstances — for 

 example, from want of sufficient exercise — the fat tends to 

 accumulate around the base and origin of the great vessels, 

 and also to gradually insinuate itself between the muscle 

 fibres. The fat is always more abundant near the 

 surface. 



Fatty Metamorphosis. — This condition may afi'ect the 

 cardiac muscle throughout, or in portions only. The muscle 

 becomes softer and more friable, and often breaks with a 

 granular fracture. It is more flabby, paler, and more opaque 

 than normal cardiac muscle. True fatty degeneration is 

 mostly met with in cases of dilatation of the cavities with 

 thinning of the walls of the heart. It is also a not uncom- 

 mon result of aortic incompetence^ in which disease the 

 circulation in the coronary arteries is interfered with, and 

 the heart muscle is badly nourished in consequence. 



Diffuse fatty degeneration sometimes occurs in acute 

 specific fevers. 



There are no diagnostic symptoms of fatty change in the 

 heart, though degeneration renders the organ weak and in- 

 capable of performing any unusual exertion, or, if advanced, 

 of even carrying on the normal circulation. 



CALCAREOUS DEGENERATION OF THE HEART.— 

 Cases of calcareous change in the cardiac muscle of the horse 

 are very rarely met with. Only two cases are recorded, 

 and in each the right auricle only was calcified. 



RUPTURE OF THE HEART.— Kupture of the heart is 

 very rarely met with. In most instances it is due to some 

 previous pathological condition of the organ. The imme- 



13—2 



