Abstract
The radiological changes observed in 108 cases of experimentally induced avian osteopetrosis are described. The distribution of lesions in the skeleton and the age at which changes first appear in different bones is reported. It is considered that the radiological changes in the long bones may be divided into 4 groups. Generally the changes which develop in other parts of the skeleton resemble those in the long bones. Although 20% of the birds also had soft tissue tumors it is considered unlikely that these influenced the development or type of bone lesions produced by this viral agent. The initial reaction of the long bone periosteum represents a characteristic response to any stimulus. The radiological changes in the bird are compared with certain human bone diseases which show, in some stage of their development, a somewhat similar radiological picture.