A quantitative histologic study of osteoporosis produced by nutritional secondary hyperparathyroidism in dogs

Nutritional secondary hyperparathyroidism (NSH) was induced in adult beagle dogs through nutritional control by a diet high in phosphorus (1.20%) and low in calcium (0.12%). A control group was fed a diet containing 0.42% phosphorus and 0.54% calcium. A statistically significant increase in iPTH level was observed at ten and 20 weeks. The femoral heads of experimental (NSH) animals showed increased osteoclastic activity and an approximately 20%-30% reduction in volume fraction cancellous bone. No abnormal osteoid seam was found in the cancellous bone of the experimental animals, and no statistically significant differences were observed in either the calcium-to-phosphorus or mineral-to-matrix ratios of the bone tissue for the two groups. Data obtained from histologic sections on the number of trabecular bone intercepts per unit length and thickness of trabeculae in the femoral head indicated a uniform, rather than specific loss of bone mass in the experimental sections. Histologic sections from the proximal femoral shaft revealed increased endosteal and periosteal diameters in the experimental group compared with the control group.