DISEASES OF THE HEART. ill 



(tuberculosis, congestion, etc.), leads to its re-opening, and the 

 arterial and venous blood mix. The blood being equally unfit 

 for nutrition and the maintenance of animal heat, there is 

 surface coldness, staring coat, puny growth, blue mucous 

 membranes, and oppressed breathing, and irregular heart's 

 action when subjected to exertion. A murmur usually precedes 

 the first heart sound. The subjects die young or prove worth- 

 less when mature. Nothing can be done to remedy unless the 

 disease is due to some remediable affection of the lungs. 



ENLARGEMENT (hYPERTROPHV) OF THE HEART. 



This is a simple increase of the muscular substance, and may 

 be confined to one side of the heart or to one ventricle. It is 

 usually caused by some obstruction to the circulation through 

 the arteries, or in horses or dogs by habitual violent work. 



Symptoffis. — The heart's beats are more forcible and pro- 

 longed, and the interval of silence shortened ; the pulse is full 

 and rolling ; the first sound is low, muffled, and prolonged, the 

 second sound unnaturally loud, and sometimes repeated if one 

 ventricle only is affected ; the heart sounds may be heard over 

 an unusually large area, the lungs being sound, and the dulness 

 on percussion is equally extended. The pulse is usually 

 regular, and if excited to irregularity or intermission soon 

 returns to its normal standard if the patient is left at rest 



Pure hypertrophy rarely implies imminent danger, and many 

 hard-worked horses survive to an old age with greatly enlarged 

 hearts. But if associated with dilatation, impaired strength, 

 livid mucous membranes, blowing murmurs with the first heart 

 sound, and paroxysms of difficult breathing, it may prove fatal 

 at any time. 



Treatment. — If possible remove the obstacle to the circula- 

 tion. Then adopt a restricted, gently laxative diet, perfect rest 

 m fattening animals or only light work in horses, and the daily 

 use of digitalis or aconite, unless there is extreme dilatation. 



