Primary bone tumors in birds: a review and description of two new cases.

Primary bone tumors are only occasionally reported in avian species. This paper presents the cases of an osteosarcoma in a 6-yr-old free-range chicken and a chondrosarcoma in a 3-yr-old barred Plymouth Rock chicken. The well-differentiated, moderately productive osteoblastic osteosarcoma arose from the synsacral vertebrae and had metastasized to the liver. The chondrosarcoma was well differentiated and firmly attached to the left side of the keel. There was no evidence of metastasis.