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Valgus-varus Deformity

Twisted Leg, Angular Bone Deformity

Valgus-varus deformity (VVD) is the lateral or medial deviation of the shaft of the distal tibiotarsal bone of the chicken, resulting in a hocks-in/feet-out (valgus) stance or a hocks-out/feet-in (varus) stance. VVD is the most common skeletal deformity found in broilers and turkeys. Most birds show signs of VVD starting at 6 days of age.

With increased age and growth, chickens affected by this deformity are more at risk of developing a slipped tendon or leg fracture, due to the increased pressure placed on the deformed leg. As the condition progresses, chickens suffering from varus deformity often show bending and rotation of the metatarsus.

As VVD progresses, and the deviation more severe, which is particularly the case in valgus deformity or when it affects both legs, slipped tendon may occur as a secondary result. Once this occurs, the chicken may be physically incapable of getting up from its abnormal, twisted leg-like position. Without intervention, these chickens will eventually starve to death from inability to reach water or food or from getting trampled to death by other flock members.

Symptoms

Legs deviating away or inward from the chicken's body
Abnormal leg stance
Lameness
Reluctance to move

Diagnosis

  • History
  • Clinical signs
  • Physical exam
  • Radiographs

Treatment

MethodDetails
Supportive care
Surgery

Prevention

  • Providing birds with a balanced diet
  • Avoid purchasing overly large, fast-growing breeds of meat chickens
  • Do not raise birds on wire or slat floor surfaces
  • Slowing growth
  • Provide long dark periods, by reducing light exposure

Scientific References

Risk Factors

  • Large, fast-growing meat chicken breeds
  • Receiving an unbalanced diet
  • Receiving a high protein, high energy diet
  • Raising birds on wire or slat floor surfaces