An intracardiac communication between the left ventricle and the right atrium (Geborde defect) was diagnosed in a 9-year Yorkshire Terrier with a history of chronic exercise intolerance. The history, clinical examination, and diagnostic imaging confirmed the diagnosis and did not reveal evidence of trauma or endocarditis which could lead to this special type of left-to-right shunting. A Gerbode defect is a very rare finding in human beings and animals. In the veterinary literature all reports about this condition were related to thoracic trauma or valvular infection. According to the authors, this would be the first clinical case of congenital Geborde defect in a dog.