Ultrasonographic and computed tomographic features of rice bodies in an Arabian horse with atlantal bursitis.

A 19-year-old castrated Arabian male horse presented for evaluation of a firm mass at the dorsal cervical region. Ultrasonography and computed tomography revealed multiple well defined fusiform structures within the atlantal bursa. Multiple glossy smooth, white to yellowish, flattened fusiform structures were removed surgically. These structures were composed of dense fibrin with some leukocytes and red blood cells. The imaging and histopathological features of these structures were similar to chronic 'rice bodies' reported in humans with bursitis or tenosynovitis. This is the first veterinary report describing the imaging features of 'rice bodies' in a horse with atlantal bursitis.