Nutritional secondary hyperparathyroidism in the animal kingdom: report of two cases

This report describes two cases of marked bone loss (osteopenia) occurring in a 9-week-old German shepherd puppy and in a 6-month-old tiger. In both cases the animals were fed a diet which was exclusively boneless meat. The diets in both cases contained approximately 40 mg of calcium and 1000 mg of phosphorus per pound resulting in both calcium deficiency and phosphorus excess, resulting in a phosphorus-to-calcium ratio of 25:1, well beyond the amounts known to cause marked loss of bone experimentally. This has been termed nutritional secondary hyperparathyroidism (NSH). Both animals presented with severe bone pain, difficulty in ambulation, and difficulty in chewing food. Radiographs showed marked osteopenia and spontaneous fractures. Both responded clinically and radiographically to calcium supplementation and a diet with an appropriate phosphorus-to-calcium ratio. The importance of calcium and phosphorus in the human diet is briefly discussed.