DISEASES OF HEART, 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-wiridedness, 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, OR 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- 
exertion or especially hard work continued for a long time may cause 
this muscle to become inflamed. 
Symptoms.—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 oandaged loosely with flannel bandages. Internally the horse 
may have strychnia in 2-grain doses twice daily, whisky in 4-ounce 
