DISEASES OF HEART, 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, hut 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 process 
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 soarked 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 
