Spontaneous dissecting aortic aneurysm in a squirrel monkey (Saimiri sciureus).

Arteriosclerosis and a dissecting aortic aneurysm were diagnosed radiographically and confirmed at necropsy in an aged female squirrel monkey (Saimiri sciureus). The radiographic findings closely resembled the analogous syndrome in man. The dissection began in the aortic arch, extended along the media, and recommunicated with the aortic lumen at the level of the renal arteries. Arterial lesions also included medial necrosis and moderate atherosclerosis.