A three-year-old, female guinea pig (Cavia porcellus) presented for acute d
yspnea and weakness. Radiographs and echocardiography were consistent with
a diagnosis of pericardial effusion and heart failure secondary to cardiac
tamponade. Ultrasound-guided pericardiocentesis was performed, and clinical
signs rapidly improved. Serial echocardiography and radiographs demonstrat
ed normalization of cardiac function over the subsequent six months.