578 CHRONIC DISEASES OF THE HEART. 



These conditions may exist separately, or tliey may be com- 

 bined. 



Situations and Symptoms of Valvular Disease. — In the diag- 

 nosis of disease affecting the valves of the heart, attention 

 must be directed — 1. To the physical or local signs of disturb- 

 ance ; 2. To the physiological or functional indications. 



In our patients, particularly the horse, the power accurately 

 to discriminate the different physical signs, which are those of 

 abnormal sounds and murmurs, is in a great measure taken 

 from us by the formation of the chest and pectoral region. 

 The close approximation to the chest of the pectoral limbs, 

 and their peculiar formation, so cover and shield the heart, 

 that anything like nice or correct auscultation is impossible. 



The abnormal sounds or murmurs which may be heard in 

 many forms of valvular disease, or of abnormal states of the 

 blood, vary much ; sometimes soft and cooing, at others harsh 

 and rasping ; sometimes accompanying or following the natural 

 sounds, sometimes so developed as to obscure them or take 

 their place. It is further worth remembering that disease of 

 the endocardial membrane, the valves and the orifices of the 

 left side of the heart, are of more common occurrence than 

 those of the right. Also that disease of these structures of 

 the left side chiefly affect the arterial pulse, rendering it un- 

 equal as to character or rhythm ; while those of the right side 

 give more distinct indications in the venous circulation, being 

 often attended with the jugular irregularity known as the 

 jugular pulse ; while effusion into the natural cavities and the 

 general connective-tissue, the attendant dropsies and anasarcous 

 swellings of cardiac disorders, are more common in disease of 

 the structures of the right than of the left side. 



Probably the most common seats of disease of the valves 

 and the orifices of the heart in the horse are in connection 

 with the mitral or aortic valvular apparatus. Disease of 

 these structures in both situations may in character be either 

 insufficient or obstructive ; commonly it possesses the double 

 feature. When the defect in the aortic valves is of the dis- 

 tinctly obstructive character, preventing the free passage of 

 the blood into the great arterial conduit from the ventricle, 

 the murmur, or abnormal bellows-sound, if heard at all, will 

 be during the systole or contraction of the ventricle ; when 



