Congenital heart diseases are not commonly diagnosed in wild animals. It is not surprising that few reports exist in the literature, so that prevalence of these anomalies is unknown in wild species. We report a case of a ventricular septal defect documented in a free-ranging crab-eating fox (Cerdocyon thous). This animal presented with rapid, labored breathing, and on physical examination, pulmonary crackles and a holosystolic murmur were auscultated. The echocardiogram with Doppler showed discontinuity of the dorsal section of the ventricular septum, which allowed a turbulent systolic flow to move from the left to the right ventricle. The postmortem examination confirmed the absence of a dorsal connection between the septum and the atrioventricular junction, and pronounced left ventricular myocardial dilation was observed on histopathology. To the authors' knowledge, this is the first report of a perimembranous ventricular septal defect in a crab-eating fox.