Veterinary advice should be sought from your local veterinarian before applying any treatment or vaccine. Not sure who to use? Look up veterinarians who specialize in poultry using our directory listing. Find me a Vet

Slipped Tendon

Slipped tendon, also referred to as "perosis", is an orthopedic condition which occurs when the gastrocnemius tendon slips out of alignment from the intercondylar groove of the hock joint. Once out of alignment, the contracture of the tendon perpetuates the condition and accelerates the leg deformity and inflammation of the joint.
Slipped tendon can occur in either or both legs. The condition usually manifests as an enlargement of the hock joint, followed by varying degrees of twisting of the tibiotarsus and bending of the tarsometatarsus bones.

Slipped tendon often occurs in young growing chicks, less than 6 weeks of age. It has generally been associated with nutritional deficiencies in the diet, but existing leg deformities and genetics also influence its onset. When chicks are fed a diet deficient in manganese, biotin, choline, niacin, or folic acid, they have an increased risk of developing a slipped tendon.

Clinical Signs

Enlargement of the hock joint
One leg extended diagonally backwards
Acute lameness
Inability to stand and/or walk


  • History
  • Clinical signs
  • Physical exam
  • Radiography

Reported Cases

  • Case 1: Slipped tendon in a Duck A male Pekin duck had a history of non-weight bearing lameness for a week. Both of the duck’s hock joints were enlarged. Physical exam revealed that the tendons were displaced to the medial side of both hocks. The tendons were both repaired surgically and the legs were splinted into the correct positions and bandaged. The duck received antibiotics (Cefotaxime 100 mg/kg IM) for 5 days and anti-inflammatories (meloxicam 0.1 mg/kg PO) for 3 days. Additional manganese was added to the duck’s daily diet in the form of rice and chickpeas. Ref


Supportive careIsolate the bird from the flock and place in a safe, comfortable, warm location (your own chicken "intensive care unit") with easy access to water and food. Limit stress. Call your veterinarian.
Bandaging/SplintingIf caught early, bandaging and/or splinting the affected leg back into place may be effective in mild cases.
SurgeryRequired in severe or longstanding cases.
AntibioticsTo help prevent secondary joint infection.
Diet changesProvide a well-balanced diet and correct any deficiencies.
Brewer's yeast2.5 to 5.0% added to the dietI Plavnik et al



  • Do not overcrowd birds
  • Provide flock with good quality poultry feed, appropriate for their stage of growth.
  • Don't supplement chicks with additional calcium sources when their still growing.


Varies mostly from guarded to poor, unless diagnosed early, and treated promptly.

Scientific References

Age Range

Most often seen in young chicks, less than 6 weeks old.

Risk Factors

  • Overcrowding or stressing out birds, increasing the risk of trauma
  • Nutritional deficiencies - Vitamin B6, Vitamin B12, Biotin, Choline, Methionine, or Manganese
  • Supplementing additional calcium in the diet of growing chicks.
  • Valgus or varus deformities of the legs.
  • Heavier weight "meat breeds"

Also Consider