40 Hounds 



so adjust themselves at the moment of contraction 

 and dilatation of the compartments that one part 

 is completely shut off from the other. 



Disease of the valves gives rise to various abnormal 

 conditions. They are composed of fibrous tissue. 

 Any interference with the working power of the 

 heart necessarily gives rise to serious conditions of 

 health, and if a hound has not a sound heart it will 

 never be able to give a satisfactory account of itself 

 in the field. The interior of the heart is lined by a 

 delicate membrane called the endocardium, similar 

 to that lining the blood-vessels. 



The large blood-vessels at the heart have small valves 

 at their entrance, regulating the flow of blood, just 

 in the same way as the bicuspid and tricuspid act. 



With reference to the circulation of blood, it may 

 be said that blood passes into the left auricle by the 

 pulmonary veins; the auricle then contracts and 

 forces the blood into the lower compartment or left 

 ventricle, which in its turn contracts and sends the 

 blood into the aorta — the largest blood-vessel in the 

 body, corresponding to the trunk of a tree. 



In response to this afflux of blood in the arteries 

 throughout the body, the walls of these vessels 

 expand synchronously with the contraction of the 

 left ventricle, and it is these undulations in the walls 

 of the arteries that constitute the pulse, which in the 

 dog averages 80 to 90 per minute. 



