DISEASES OF THE HEART. 



Diseases of the heart are best distinguished from pul- 

 monary diseases, with which they are often confounded, 

 by auscultation. The heart's beats may be felt, heard, and 

 counted, in either health or disease, and can therefore be 

 contrasted. The contrast between the action of a healthy 

 and a diseased heart should be carefully studied. Apply 

 the flat of the hand or the ear to the left side, just be- 

 hind the elbow. The stethoscope (a hollow or perforated 

 piece of wood) may also be used. In health two succes- 

 sive sounds, followed by an interval of silence, are heard. 

 Exercise and agitation increase the heart's action. 



Fig. 21. A horse with Heart Disease. 



Persistent coldness of the extremities, swelling of the 

 legs, chest, and abdomen, fainting fits, dizziness, languor, 

 difficult breathing, especially after severe exertion, are 

 more or less constant symptoms of heart disease. 



Disease of the heart is either the result of functional 

 disturbance or structural alteration. Disease of the heart 

 and its membranes may be either acute or chronic. 



