180 MANUAL OF EQUINE MEDICINK 



1. CARDIAC IMPULSE.— The impulse of the heart may 

 be felt by placing the hand directly upon the left side of 

 the chest, immediately below the elbow. It is more distinct 

 in flat-sided and thin animals, and less so, or even absent, 

 in round-chested and fat ones. The impulse may be 

 altered in position and area, in force, in character, and in 

 rhythm. 



(A.) In ijosition and area. — It may, owing to abdominal 

 distension, be displaced forwards and upwards, or it may, 

 owing to collection of fluid in the pericardium or chest, be 

 displaced upwards and laterally. 



The area over which the impulse is felt is * extended ' in 

 cardiac hypertrophy, and in adhesions of the pericardium to 

 the chest-walls. 



It is very feeble, though extended, in pericardial effusion. 



(B. ) In force and character. — The impulse is more forcible, 

 and sometimes extended over a larger area, in most cases 

 of hypertrophy, with dilatation and incompetence of the 

 valves. In these cases it is rather slow and steady, and 

 occasionally appears to be produced not only when the 

 heart contracts, but when it commences to dilate. This 

 latter is called diastolic impulse. 



Diminished impulse indicates feebleness of the heart. 

 This may be due to degeneration, or to weakness of the 

 heart owing to thinning of the walls or to general disease 

 of the system. 



It is also diminished in eff'asion into the sac of the 

 pericardium, and may be lessened owing to pericardial 

 adhesions. 



(C.) In rhythm. — May be irregular in force, at one time 

 strong, at another weak, or it may be irregular in time or in 

 character. 



2. CARDIAC SOUNDS IN HEALTH AND DISEASE.— 

 When the ear is placed over the cardiac area, two sounds 



