238 DISEASES OF THE HORSE. 



of myocarditis, and it may arise from a long-continued increase of 

 action dependent upon nervous disease. All the cavities of the heart 

 may have their walls hypertrophied or the thickening may involve 

 one or more. While the wall of a ventricle is thickened, its cavity 

 may retain its normal size {simple hypertrophy^ or be dilated {eccen- 

 tric lujpertrophy) ^ or it may be contracted {concentric hypertrophy) . 

 Hypertrophy of both ventricles increases the length and breadth of 

 the heart. Hypertrophy^ of the left ventricle alone increases its 

 length ; of the right ventricle alone increases its breadth toward the 

 right side. Hypertrophy with dilatation may affect the chambers 

 of the heart conjointly or separately. This form is by far the most 

 frequent variety of cardiac enlargement. ^A'lien the entire heart is 

 affected, it assumes a globular appearance, the apex l3eing almost 

 obliterated and situated transversely in the chest. The bulk may 

 become three or four times greater than the average heart. 



Sy7npto'ms. — In hypertrophy of the heart, in addition to the usual 

 symptoms manifested in organic diseases of the heart, there is a pow- 

 erful and heaving impulse at each beat, which may be felt on the left 

 side, often also on the right. These pulsations are regular, and when 

 full and strong at the jaw there is a tendency to active congestion of 

 the capillary vessels, which frequently gives rise to local inflamma- 

 tion, active hemorrhage, etc. If the jDulse is small and feeble at the 

 jaw, we may conclude that there is some obstacle to the escape of the 

 blood from the left ventricle into the aorta, which has given rise to 

 the hypertrophy. In case of hypertrophy with dilatation, the im- 

 pulse is not only powerful and heaving, but it is diffused over the 

 whole region of the heart, and the normal sounds of the heart are 

 greatly increased in intensity. Percussion reveals an enlarged area 

 of dullness, while the impulse is usually much stronger than normal. 



Dropsy of the pericardium will give the same wide space of dull- 

 ness, but the impulse and sound are lessened. An animal with a 

 moderate degree of enlargement may possibly live a number of years 

 and be capable of ordinary work; it depends largely upon con- 

 comitant disease. As a rule, an animal affected with hypertrophy 

 of the heart will soon be incapacitated for work, and it becomes 

 useless and incurable. 



Treatment. — If the cause can be discovered and is removable, it 

 should be done. The iodide of potassa, in cases of valvular thicken- 

 ing, may be of some benefit if continued for a sufficient length of 

 time ; it may be given in 2-dram doses, twice a day, for a month or 

 more. The tincture of digitalis may be given, in cases where the 

 pulse is weak, in doses of 2 teaspoonfuls three times daily. This 

 remedy should not be continued if the pulse becomes irregular. 

 General tonics, freedom from excitement or fatigue, avoidance of 

 bulky food, good ventilation, etc., are indicated. 



