184 MANUAL OF EQUINE MEDICINE. 



only. It appears superficial, and as though close under 

 the ear. 



When much effusion into the sac follows the dry stages of 

 inflammation, the sound is no longer produced, owing to 

 the separation of the roughened surfaces by the fluid. 



When the pleura over the pericardium is inflamed, the 

 movement of the heart may cause a friction by the rubbing 

 of the two layers of the pleura. This is pleuro-pericardial 

 friction, its origin being in the pleura over the peri- 

 cardium. 



GENERAL OBJECTIVE SYMPTOMS OF CAR- 

 DIAC DISEASE. 



Palpitation. — Palpitation, or tumultuous rhythmical 

 action of the heart, is a common symptom in functional and 

 organic disease of the heart or pericardium. 



It occurs when there is more or less sudden demand of 

 work from the heart in excess of its powers, as in acute or 

 chronic diseases of the heart and pericardium, ansemia and 

 debility, in altered conditions of the quantity and quality of 

 the blood, as in anaemia and plethora, and in some specific 

 and other general diseases. 



If the additional strain put upon the heart be sudden 

 and temporary, the result is only a transient attack of 

 palpitation. If persistent, hypertrophy may be induced. 



It may also be caused by nervous influences. The latter 

 may be of reflex origin, as when palpitation accompanies 

 acute or chronic intestinal disease ; or it may be of central or 

 intrinsic origin. 



Palpitation may be continuous, or may occur at intervals 

 only. It is generally accompanied by increased frequency 

 and apparent force of the heart's action, and may be regular 

 or irregular in force and in rapidity. 



