Signs of right heart failure predominate in milder cases and signs of low cardiac output are featured in severe cases. Muffled heart sounds - in smaller animals not always muffled. Other signs of right heart failure are often present. Electrocardiography Diminished QRS voltages in all leads. Nonspecific S-T segment elevation and T wave enlargement.
Sinus tachycardia is usually present - other atrial and ventricular arrhythmias are uncommon.
Small pericardial effusions may be undetectable, or may simulate other causes of cardiomegaly. Pleural effusion may also obscure the cardiac silhouette. With large effusions, the typical findings are an enlarged, globular cardiac silhouette, round on both views, with loss of individual chamber contours. Other findings reflect right heart failure - caudal vena caval enlargement, pleural effusion. Echocardiography Echocardiography is the most accurate and sensitive technique for detecting pericardial effusion.