Persistent left cranial vena cava associated with multiple congenital anomalies in a six-week-old puppy

A six-week-old male puppy was presented with a distended abdomen, dypsnoea and cyanosis. Auscultation revealed a grade II/VI systolic murmur. Thoracic radiographs showed gross cardiomegaly. An electrocardiogram revealed a narrow-complex tachycardia, deep S waves in leads I, II, III and aVF, and negative P waves in lead III. Two-dimensional echocardiography showed a high ventricular septal defect and marked dilation of the right-sided chambers. There was also an echolucent structure lateral to the left atrium at a site corresponding to the coronary sinus. Contrast echocardiography revealed right-to-left shunting through the septal defect. Necropsy confirmed the existence of a septal defect in the membranous part of the septum and a persistent left cranial vena cava with dilation of the coronary sinus. In addition, a small patent ductus arteriosus and tricuspid dysplasia were present.