Third degree atrioventricular block following non-penetrating chest trauma in a dog

A two-year-old mixed breed dog was referred to the University of Florida Veterinary Medical Teaching Hospital for the management of post traumatic ventricular arrhythmias. Electrocardiography revealed third degree atrioventricular (AV) block. An echocardiogram demonstrated an echogenic, pedunculated mass arising from the caudoventral aspect of the atrial septum. The mass was believed to represent a haematoma or a thrombus associated with trauma to this region of the atrial septum. The patient was managed conservatively; third degree AV block was still pre- sent five days after trauma. The owner of the dog refused specific therapy of the arrhythmia. The patient was discharged and, unfortunately, lost to follow-up. Third degree AV block has not previously been reported following accidental, blunt thoracic trauma in the dog.