Introduction

A complex condition of broiler chickens with a morbidity of 1-5% and low mortality associated with rapid growth and possibly having a genetic component.

Signs

• Sitting on hock or rumps, legs extended forward.
• Use of wings to help in walking.
• May walk backwards.

Post-mortem lesions

• Anterior-posterior rotation of the bodies of the last or penultimate thoracic vertebrae resulting in scoliosis just anterior to the kidney.

Diagnosis

Symptoms, lesions.

Treatment

None.

Prevention

Selection for satisfactory conformation in primary breeding.

Figure 33. These are cross-sections of the spinal column of 4-5-weekold broilers. The sample on the right is normal. That on the left shows the typical lesion of spondylolisthesis, with rotation of the body of the vertebra and the pinching of the spinal column that causes paralysis.