Metabolic bone disease resembling osteosarcoma in a wooly monkey (Lagothrix lagotricha)

A female pet wooly monkey with metabolic bone disease initially presented with a proliferating bony mass in the left humerus which had many features of osteosarcoma. At necropsy, parathyroid hyperplasia, osteoclastic resorption, proliferative osteoid deposition in the calvarium and cortex of long bones, and fibrous proliferation of the marrow indicated the presence of generalized osteodystrophia fibrosa. The dietary history of deficient vitamin D3 and protein and minimal exposure to sunlight supported this diagnosis, as did depressed levels of serum calcium and elevated levels of serum parathyroid hormone, alkaline phosphatase, and acid phosphatase.