DISEASES OF THE HORSE. 231 



slowlj^ at first, but ultimately seriously impair the animal's usefulness. 

 What was but a slight olxstruction 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 corre- 

 sponding fullness of the left auricle and pulmonarj- veins, thereby pro- 

 ducing fullness of the capillaries in the lungs, pressure upon the air 

 cells, difiicult or asthmatic breathing — greatl}" increased in attempts to 

 work — until in a few months many of these cases become entirely dis- 

 abled for work. Sometimes, too, dropsical effusions in the limbs or into 

 the cavities of the body result from the irregular and deficient circula- 

 tion. Derangement of the urinary secretion, with passive congestipn 

 of the kidneys, ma}^ 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. 



Symjytonis. — 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 earl}' 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 com- 

 pelled to'trot; very often difficult}' 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 regurgitant pulsation in the 

 jugular vein. Occasionally it happens that the heart contracts more 

 frequently than the j)ulse 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 against the chest wall will not pro- 

 duce pain unless roughly applied. The animal is not disposed to eat 

 or drink much; the surface of the body and legs is cold — rarely exces- 

 sively hot — and frequently the body of the animal is in a subdued tre- 

 mor. In nearly all cases there is partial suppression of the urinary 

 secretion. The symptoms may continue with very little modification 

 for three or four days, sometimes seven days, witliout any marked 

 changes. If large fibrinous clots form in the heart the change will be 



