Osteochondrosis, dyschondroplasia, and osteomyelitis causing femoral head necrosis in turkeys.

Femoral head necrosis is a term that has been used, frequently inappropriately, to describe a variety of lesions in the head and proximal femur of poultry. In a survey of causes of lameness in a group of 18,000 tom turkeys, examination of femurs from lame 16-to-30-week-old heavy male turkeys with femoral head necrosis revealed that the lesions could be placed in one of three categories: degeneration of articular or growth plate cartilage and bone, with separation usually between the growth plate and metaphysial bone; avascular necrosis with sequestration and degeneration of an abnormal mass of prehypertrophying cartilage (dyschondroplastic cartilage), with spontaneous fracture and collapse of the femoral head or fracture through the metaphyses or neck of the femur; and osteomyelitis, with necrosis usually beneath the growth plate in the metaphyses. The second and third categories of lesion were frequently found in the proximal tibia as well, so the term long-bone necrosis would be a more suitable morphologic description than femoral head necrosis.