s 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 capillaries in the lungs, pressure upon the air cells, difficult or
asthmatic 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 sudden 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 correspond 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 affecte