Pericardial diseases are not as common as
valvular, myocardial or congenital heart diseases, but are encountered reasonably
frequently in practice and they are probably one of the more common causes of right-sided
congestive heart failure in dogs. However, pericardial disease is rare in the cat.
The pericardium envelops the heart and proximal
portions of the great vessels, and it consists of two membranes: a thin visceral
pericardium (epicardium) adherent to the myocardium, and a thicker parietal pericardium
(pericardial sac). Between these two membranes is the pericardial space containing
1-15 ml of a serous fluid.