Even the most competent
specialist in canine diseases often finds it
difficult to establish clinical diagnoses of the ailments of the
heart. It is apparent, therefore, that any detailed description of
heart diseases would be of little value to the general reader. However,
the intelligent person in the modern world should have some idea of
what some of the terms associated with heart diseases signify, since
they are so commonly mentioned in everyday conversation.
The heart is covered by a double membrane which forms a sac around it.
This membrane is called the pericardium, and the sac is called the
pericardial cavity. An inflammation of the pericardium is called
pericarditis. Where a watery fluid accumulates in the pericardial
cavity as a result of some inflammatory process, the condition is
called hydropericardium. When blood accumulates in the pericardial
cavity, the condition is called hemopericardium.
The heart of dogs, as well as that of man, consists of four chambers.
Between these chambers are structures known as valves. When the blood
is pumped from one chamber to another and from there to the rest of
the body, it is the function of these valves to block off the backward
flow of blood so that there will be no interference with the impetus
which that blood has obtained from the heart. When there is improper
closure of the valves, the condition is known as valvular
insufficiency. This will give rise to a sound commonly called a heart
murmur. Sometimes, when the valves are relaxed, they may have some
involvement whereby they do not permit proper flow of blood through the
blood chambers. In other words, they
tend to remain nearly closed all the time. This condition is called
The muscle tissue of the heart is called the myocardium. An
inflammation of this structure is called myocarditis. The lining
membrane of the heart chamber is the endocardium. An inflammation of
the endocardium is called endocarditis. Where there is an abnormal
increase in the size of the heart due to the increase in the quantity
of muscle tissue, the condition is called hypertrophy of the heart.
When the heart increases in size due to the enlargement of the heart
chambers, the condition is called dilatation of the heart. When the
heart is ruptured due to injury or any other cause, then the
designation rupture of the heart is applied to the involvement.