Overview

Of all the causes of pericardial disease, the development of pericardial effusion is the most frequent pathogenic process or consequence of the pericardial disorder. The clinical signs of the pericardial disorder are thus a consequence of the pericardial effusion.

Pericardial effusion is the disorder characterized by the accumulation of fluid (serous, blood, chyle, pus) within the pericardial sac. As fluid collects it markedly impedes the filling ability of the heart (diastolic dysfunction). The right side of the heart tends to “suffer” most with this diastolic dysfunction.

Pericardial effusion may develop relatively slowly or may develop rapidly. If the fluid accumulates rapidly, right heart dysfunction occurs rapidly. If the fluid accumulates gradually, the pericardium can stretch to accommodate a great volume of fluid with minimal cardiac impairment.

Etiology: The idiopathic and neoplastic etiologies are by far the most common in the dog. Hemangiosarcoma (HSA) is the main tumor. Heart base tumor is another (most commonly chemodectoma or ectopic thyroid carcinoma). The disorder is uncommon in cats. The neoplastic (HSA) cause is the most common of all causes.