442 DISEASES OF THE CIRCULATORY SYSTEM, 



second is due exclusively to the rotation of the heart and to closure 

 of the semilunar valves. The precision and clearness of the heart 

 sounds indicate the healthy action of its valvular apparatus. 



V. The Tieart bruits are endocardiac (intra-cardiac) or pericardiac 

 (extra-cardiac). 



1. The endocardiac bruits are distinguished as organic (due to 

 an obstacle to the circulation) and anorganic or accidental (pro- 

 duced by irregular undulations of the valves without the existence 

 of a true circulatory obstacle) ; the importance of these latter is 

 entirely secondary. The organic bruits are produced by valvular 

 alterations occasioning insufficiency or contraction. In contractions 

 the liquid bruit is due to the vibrations of the blood-flow, which is 

 forced through a too narrow opening ; in insufficiencies it is pro- 

 duced by the return of the blood in the cardiac compartment which 

 is situated above the diseased valve. The systolic bruits are blow- 

 ing and buzzing ; the diastolic bruits, on the contrary, are quiver- 

 ing and whistling. The first are generally determined by an 

 insufficiency of the auriculo- ventricular valves, mainly of the 

 mitral, sometimes by the contraction of the openings of the aorta 

 and pulmonary vessels. The diastolic bruits indicate a contrac- 

 tion of the auriculo-ventricular openings, especially of the mitral 

 orifice, or an insufficiency of the aortic valves. These alterations 

 -are much more rare in the right heart. 



2. The pericardiac bruits are friction noises ; they are distin- 

 guished from the endocardiac bruits by the fact that they are not 

 intimately related to the act of systole or diastole. 



In the horse we find quite frequently a doubling of the heart 

 sounds. It is mostly the first which presents this anomaly ; it 

 may be observed upon subjects which are otherwise perfectly 

 healthy ; it should be counted among the anorganic bruits ; it is 

 Tery probably the consequence of an unequal tension of the mitral 

 or tricuspid valves. 



VI. In the horse and the ox we may investigate (count) the 

 pulse at the external maxillary artery (more rarely the brachial, 

 temporal, tibial, and the collateral of the canon); in small animals 

 it is taken at the femoral artery. Outside of their number (see 

 Cardiac Impulse) the pulsations also present peculiar character- 

 istics which cause us to distinguish : 



1. Regular pulse (rhythmic) or irregular pulse (arrhythmic), ac- 

 cording to the equal or unequal intervals separating the pulsations; 



