Congenital partial pericardial defect affecting the right ventricle in a dog

A 1.8-year-old, 7.7-kg male mixed-breed dog was examined before castration surgery. Thoracic radiographs showed a prominent bulging of the cardiac silhouette. Echocardiography revealed a partial absence of the bright pericardial signal in the right ventricular outflow tract. Fluoroscopy revealed a bulging pulsating sac anterior to the right ventricular outflow tract. On contrast-enhanced computed tomography, a balloon-shaped right ventricular lumen protruding in the cranial direction was seen on the cranial side of the right ventricle near the pulmonary infundibulum. Accordingly, right ventricular herniation due to a partial pericardial defect was diagnosed. This report describes cardiac computed tomography in dogs with right ventricular pericardial defects; our findings highlight the usefulness of fluoroscopic examination in diagnosing pericardial defects.