Fatal tracheal collapse and ossification in an osteopenic captive Indian blue peafowl in California.

A captive, 5-y-old, female, Indian blue peafowl (Pavo cristatus) was submitted for postmortem examination and diagnostic work-up following 24 h of open-mouth breathing, lethargy, and drooping of wings. Grossly, the trachea was diffusely, dorsoventrally flattened with irregular walls and significant narrowing of the lumen. There was no evidence of trauma in the surrounding skin, subcutaneous tissue, or esophagus. Microscopically, tracheal cartilage was diffusely replaced by immature bone tissue with wide medullary cavities containing thin, immature, and disorganized trabeculae covered by abundant osteoclasts. The proximal tibiotarsus and femur were osteopenic, with thin compact cortical bone, multifocally distended osteonic canals, and increased osteoclastic activity and fibrosis on endosteal surfaces of affected trabeculae. Concurrent tracheal collapse and osteopenia have not been reported previously in an Indian blue peafowl, to our knowledge.