Ventricular septal defects are a relatively common congenital cardiac disease that, when severe, can be associated with substantial morbidity and mortality. Several minimally invasive methods of repair have been described in the human literature. This report describes the first case of percutaneous closure of a naturally occurring muscular septal defect using an Amplatzer occluder in a dog affected by concurrent pulmonic stenosis. Based on this experience catheter-based occlusion of muscular ventricular septal defects is a feasible option in dogs. Further studies are necessary to identify the attributes and limitations of the technique.