Introduction

A condition of chickens and turkeys seen worldwide. The cause remains to be confirmed, but it may result from physical damage, or developmental defects.

Morbidity and mortality are low but affected birds are more likely to be 'picked upon' and may end up suffering damage and needing to be culled. Rapid growth is a possible predisposing factor.

Signs

• Lameness.
• Reduced breeding performance.

Post-mortem lesions

• Damaged epiphyseal articular cartilage, especially of femoral anti-trochanter but also other leg joints, resulting in erosions, and cartilage flaps.
• Microscopically there is necrosis and there may be fissures of articular cartilage and associated osteochondritis.

Diagnosis

Gross and microscopic lesions.

Treatment

None available. Appropriate management of a segregation pen and early marketing of mildly affected birds may limit losses and improve flock welfare.

Prevention

Avoidance of physical sources of injury to bones and joints.

There may be a place for growth-control programmes, especially during period of rapid growth.