EN
Atrial septal defects (ASDs) are a group of congenital heart defects which consist in an abnormal formation of the atrial septum and allow blood to flow directly between the atria. A one-month-old female lamb was presented with chronic progressive dyspnea. Clinical examination, X-ray and echocardiography revealed a congestive heart failure due to a large septal defect with a pathologic right-left shunt over the atrial septum. Symptomatic treatment brought only short-term relief, and the lamb was euthanized. Necropsy confirmed the tentative diagnosis of an ostium secundum-type ASD. To our knowledge, this is the first report on a diagnosis of an ostium secundum-type ASD associated with advanced clinical symptoms of a congestive heart failure in a lamb.