DISEASES OF HEAET, BLOOD VESSELS, AND LYMPHATICS. . 253 



while the effects of the inflammation in the membrane lining the 

 walls of the ventricles may subside to such a degree as to cause little 

 or no inconvenience, or even wholly disappear, yet after the valvular 

 structures have been involved, causing them to be thicker, less flexible 

 than normal, they usually remain, obstructing the free passage of the 

 blood through the openings of the heart, thereby inducing secondary 

 changes, which take place slowly at first, but "ultimately seriously 

 impair the animal's usefulness. What was but a slight .obstruction to 

 the circulation during the first few weeks after the subsidence of 

 the cardiac inflammatory attack becomes in process of time so much 

 increased as to induce increased growth in the muscular structure of 

 the heart, constituting hypertrophy of the walls of the ventricles, 

 more particularly of the left, with corresponding fullness of the left 

 auricle and pulmonary veins, thereby producing fullness of the cap- 

 illaries in the lungs, pressure upon the air cells, difficult or asth- 

 matic breathing — greatly increased in attempts to work — ^until in a 

 few months many of these cases become entirely disabled for work. 

 Sometimes, too, dropsical effusions in the limbs or into the cavities 

 of the body result from the irregular and deficient circulation. 

 Derangement of the urinary secretion, with passive congestion of 

 the kidneys, may also appear. 



Endocardial inflammation is seldom fatal in its early stages, but 

 in many cases the recovery is incomplete, for a large proportion is 

 left with some permanent thickening of the valves, which constitutes 

 the beginning of valvular disease. 



Symptoms. — Endocarditis may be ushered in by a chill, with sud- 

 den and marked rise in temperature. The pulse rapidly decreases 

 in strength or may become irregular, while the heart beats more or 

 less tumultuously. In the early stages soft-blowing sounds may be 

 heard by placing the ear over the heart on the left side, which corre- 

 spond in number and rhythm to the heart's action. Excessive pain, 

 though not so great as in acute pleuritis, is manifested when the 

 animal is compelled to trot; very often difficulty in breathing, or 

 shortness of breath, on the slightest exertion develops early in the 

 attack. When the valves are involved in the inflammatory proces? 

 the visible mucous membranes become either very pale or very dark 

 colored, and fainting may occur when the head is suddenly elevated. 

 When the valves of the right side are affected we may find a regurgi- 

 tant pulsation in the jugular vein. Occasionally it happens that the 

 heart contracts more frequently than the pulse beats — that is, there 

 may be twice as many contractions of the heart in a minute as there 

 are pulse waves in the arteries. The pulse is always very fast. In 

 some cases we find marked lameness of the left shoulder, and when 

 the animal is turned short to the left side he may groan with pain, 

 and the heart's action become violently excited, although pressure 



