Abstract
Background: Atrial septal defect (ASD) is a rare congenital cardiac disease, and there had been no reports about treatment of ASD in midget breed dogs.
Case Description: A 7-month-old female toy poodle weighing 1.4 kg was presented with cardiac enlargement. Echocardiography revealed a secundum type ASD, right ventricular and atrial enlargement, and pulmonary hypertension. Blood flow through the ASD exhibited left-to-right shunting. The dog underwent ASD closure via a hybrid approach, in conjunction with catheter techniques and thoracotomy. Ten months after treatment, cardiac enlargement and pulmonary hypertension were improved.
Conclusion: Even in small breeds of dogs ASD can be corrected via a hybrid approach.

Key words: canine, cardiology, catheter, congestive heart failure, small breed