Abstract
Hyperparathyroidism was produced experimentally in 23 rapidly growing kittens with an immature skeleton by feeding a diet of beef heart and distilled water. The experimental diet was deficient in calcium but contained an adequate amount of phosphorus. Weekly serum analyses revealed a significant hypocalcemia after feeding the diet for 3 weeks. The parathyroid glands of experimental cats were hyperplastic and were dominated by hypertrophied light chief cells. There was a generalized decrease in density of the bones roentgenographically by the 3rd week with a loss of fine trabeculation and thinning of bone cortices in the appendicular skeleton. Clinical signs were first observed at 4 weeks. The cats developed a posterior lameness, were quiet and reluctant to move. The skeletal lesions of increased osteocytic and osteoclastic resorption, osteoblastic apposition, diminished mineral content, and replacement of resorbed bone by fibrous connective tissue were considered to be a morphologic reflection of increased secretion of parathyroid hormone. The osteitis fibrosa produced in kittens differed from the osteoporosis reported in adult cats with a mature skeleton fed a similar diet.