Diseases of the pericardium are relatively uncommon in small animal veterinary medicine but when they do occur, they can potentially be life threatening. Pericardial effusion is the abnormal accumulation of fluid within the pericardial cavity. Within the canine population, approximately 80-90 percent of pericardial effusions are due to either neoplastic or idiopathic causes. 1,4 A life-threatening sequel to pericardial effusion is the development of cardiac tamponade. This occurs when the intrapericardial pressure exceeds that of the right atrium and/or right ventricle. The end results of cardiac tamponade are decreases in venous return, diastolic ventricular filling, stroke volume and ultimately cardiac output.2 This case study will highlight an 8 year old male intact Staffordshire bull terrier, presenting to Cornell’s Emergency Service for abdominal distention. The history, physical examination findings, pathophysiology, etiologies, diagnostics, therapeutics, and prognoses for patients with pericardial effusion and cardiac tamponade are discussed.