Atrial Septal Defect (Secundum Type) in Dogs- A Study for 15 Years

Background: Congenital anomalies in dogs are the defects present at birth and often lead to perinatal death if it involves any vital organ or system like cardiovascular system. Some dogs may remain asymptomatic or may have non cardiac manifestations and hence, undetected until later in life, so the percentage of dogs with congenital heart diseases that survive to adulthood can be rather high. Atrial septal defect (ASD) is an unusual congenital heart disease in dogs that is characterized by communication between the two atria due to a defect in the interatrial septum. Methods: A thorough clinical examination followed by physical examination, thoracic radiography and 2d-echocardiography was performed to determine the septal defect. Doppler evaluation of ASD dogs was carried out to confirm the blood flow direction through the septal defect, which was managed medically. Result: In the present study, ASD (secundum type) was diagnosed in 7dogs (7.5%) aged between 2y-6y. Boxer, German shepherd, Cocker spaniel, Daschund and Pomeranian were the breeds affected. Soft systolic murmur on left heart base and pulmonic valve area, low intensity heart sounds, distended jugular vein, jugular pulse and ascites were the significant findings on physical examination. Though few dogs (21%) were asymptomatic, exercise intolerance, dyspnoea, general weakness, cough and syncope were the presenting signs among other cases. Enlarged right heart, pleural effusion and pulmonary overcirculation were radiographic findings. 2d-echocardiographic evaluation determined the presence of the defect as a loss of echogenicity at the interatrial septum and presence of interatrial communication of varied size, enlargement of main pulmonary artery and thick atrio-ventricular valves but with normal left atrium:aorta base ratio, increased fractional shortening, systolic function and paradoxal septal motion. The colour flow Doppler study demonstrated a continuous flow with left-to-right shunt.