Abstract
A 1-year-old domestic longhair cat presented to our hospital with a 4-month history of progressive exercise intolerance and coughing. Two-dimensional echocardiography confirmed the presence of an intrapericardial cyst and cardiac tamponade. Tamponade was relieved via percutaneous aspiration of the cyst. The cyst was surgically excised 4 days later, and histopathology was consistent with a biliary cyst. The cat's clinical signs completely resolved following surgery.