Experimental Ostitis Fibrosa Cystica in Dogs.

Abstract

In previous reports the production in the guinea pig of fibrous bone lesions by injection of parathyroid extract was described, as well as its effects on the serum calcium and phosphorus. 1 , 2 The production in dogs of ostitis fibrosa cystica is possible, but more difficult. The difficulty lies in the fact that in the dog doses of parathyroid extract (Parathormone Collip) necessary to produce marked resorption of the bone and marrow injury, are liable to lead to fatal hypercalcemia before there is much fibrous repair.

We studied eleven growing puppies for periods from 10 to approximately 180 days. They were under the influence of increasing doses of hypercalcemia parathormone. We produced, depending upon the dosage and the length of time under parathormone, all degrees of change from mild bone resorption and slight fibrous replacement of the marrow to severe bone resorption and degeneration of the marrow with hemorrhage, when the animals died from overdosage. Finally, we produced typical ostitis fibrosa cystica in 3 dogs that were injected for 5 to 6 months. In these we gradually increased the daily dose of parathormone. At the end of the experimental period they were receiving 20 units daily.

The dogs with the more pronounced lesions showed: (1) resorption of the existing spongy and cortical bone, (2) invasion of the enlarged haversian spaces and of the marrow canal by fibrous tissue, (3) the presence of Howship's lacunae, containing osteoclasts, on the walls of the haversian spaces, on the inner and outer surfaces of the compacta, and on the surfaces of the spongy trabeculae, (4) new bone formation (osteoid tissue), as a substitute for the original lamellar bone, and (5) cysts and hemorrhages in the marrow cavity.