Naturally occurring aortic aneurysms in owl monkeys (Aotus spp.).

Spontaneous aortic aneurysms were diagnosed in 22 owl monkeys (Aotus spp.) at necropsy. There were 6 males and 16 females. Clinical findings varied including weight loss, weakness, and lethargy and were not present in all animals. Aortic lesions ranged in size from 2 mm to 3 cm in diameter. Nineteen of the aneurysms were classified histologically as dissecting and three as saccular. Lesions occurred less often in karyotype I monkeys than in karyotype II or III monkeys. The etiopathogenesis of aortic aneurysm in owl monkeys is unknown.