Oxyphil cells in a red-tailed hawk (Buteo jamaicensis) with nutritional secondary hyperparathyroidism.

A captive, immature red-tailed hawk (Buteo jamaicensis) was presented with multiple long-bone fractures, a serum calcium of 7.9 mg/dl, and a history of being fed an all-meat diet. Gross and microscopic examinations of the parathyroid glands revealed marked glandular hypertrophy and the presence of interlacing cords and clusters of light chief cells and oxyphil cells in approximately equal numbers. Bone sections showed severe fibrous osteodystrophy. These findings support the observation that the oxyphil cell is a product of continued stimulation, and they suggest that hypocalcemia may be a stimulating factor.