Vet Cardiology. More than 60 cardiac diseases and conditions in small animal veterinary Congenital: Atrial Septal Defect. Double Aortic Arch. Patent Ductus Arteriosus. Persistent Right Aortic Arch. Tetralogy of Fallot. Ventricular Septal Defect. Valve Diseases: Aortic Stenosis. Atrioventricular Valve Dysplasia. Atrioventricular Valve Endocardiosis.