Bilateral auricular aneurysm with intact pericardial sac in a dog

A nine-year-old, male, Pekingese dog was presented with a history of dyspnea, lethargy, syncope, polyuria, polydipsia, and selective appetite over two years. When the clinical signs first began, a radiographic exam revealed a radiopaque mass in the cranial mediastinum. An adequate treatment was not performed and the dog was presented to the hospital with severe tachycardia, dyspnea, and tachypnea, and died during physical examination. On necropsy, the heart presented bilateral auricular aneurysms. The pericardial sac was intact, and no other defects were found within the heart. Microscopically, the cardiomyocytes were marked degenerated and proliferation of connective tissue. This is the first case report of a bilateral auricular aneurysm with intact pericardial sac in a dog.