DISEASES OF HEAET, BLOOD VESSELS, AND LYMPHATICS. 251 



Disease of the heart may occur at any age, but it is witnessed most 

 frequently in young horses, which, when being trained for fast work, 

 are often subjected to excessive hardship and fatigue. Nervous or 

 timid animals also suffer from such diseases more frequently than 

 those of a sluggish disposition. Any cause which induces a violent 

 or sudden change in the circulation may result in injury to the heart. 

 Symptoms which may frequently denote disease of the heart are 

 difficult breathing or short-windedness, dropsies of the limbs, ha- 

 bitual coldness of the extremities, giddiness or fainting attacks, in- 

 ability to stand work, although the general appearance would indi- 

 cate strength and ability, etc. 



MYOCARDITIS, OE INFLAMMATION OF THE MUSCULAR STRUCTURE OF THE 



HEART. 



The heart muscle sometimes becomes inflamed as a complication or 

 result of the existence of general or febrile and of infectious diseases. 

 Severe influenza or infectious pneumonia is not infrequently followed 

 by myocarditis. By extension of inflammation of the endocardium 

 or pericardium the muscle of the heart may become involved. Over- 

 exei-tion or especially hard work continued for a long time may cause 

 this muscle to become inflamed. 



Symft&ms. — Inflammation of the heart muscle is shown by inabil- 

 ity to contract forcibly. This results in a rapid but weak, soft pulse 

 and irregular heart sounds. The pulse may be quite irregular as a 

 result of the irregular, tumultuous action of the heart. There is 

 great general weakness, shortness of breath, and rapid respiratory 

 movements. In some cases, where the muscle is very much softened 

 and weakened, or, perhaps when an abscess forms in the wall of the 

 heart, the course of the disease is very rapid and terminates suddenly 

 from paralysis or rupture of the heart. 



Alterations.^ — The heart muscle has a brownish or yellowish, boiled 

 appearance, and is so brittle that it tears easily. There may be a 

 spotted appearance of the muscle from the intense changes in struc- 

 ture in small areas. These small areas may be due to suppuration, in 

 which case they have the characteristics of small abscesses. This last 

 condition is seen in pyemia (blood poisoning). If the disease is of 

 long duration, the fibrous tissue in the wall of the heart may increase 

 to such an extent as to produce an unnatural hardness of the wall. 



Treatment. — In this disease the nutrition and strength of the heart 

 should be kept up as much as possible with good food, good care, 

 and heart tonics and stimulants. The horse should be tempted to eat 

 such foods as he will take ; he should be kept in an airy box stall ; his 

 legs should be well rubbed as often as necessary to keep them warm 

 and bandaged loosely with flannel bandages. Internally the horse 

 may have strychnia in 2-grain doses twice daily, whisky in 4-ounce 



