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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

Diagnosis

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

Treatment

Name	Summary
Supportive care	Isolate 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/Splinting	If caught early, bandaging and/or splinting the affected leg back into place may be effective in mild cases.
Surgery	Required in severe or longstanding cases.
Antibiotics	To help prevent secondary joint infection.
Diet changes	Provide a well-balanced diet and correct any deficiencies.
Brewer's yeast	2.5 to 5.0% added to the diet	I Plavnik et al

Support

Prevention

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.

Prognosis

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

Scientific References

Baron, Hamish R., David N. Phalen, and Mikel Sabater Gonzalez.. A Novel Technique for Extracapsular Repair of the Intertarsal Joint in a Duck Journal of avian medicine and surgery 32.1 (2018)
Graham, Jennifer E., ed. Blackwell's Five-Minute Veterinary Consult: Avian. John Wiley & Sons (2016)
Wideman, R. F., et al. Efficacy of 25-OH Vitamin D3 prophylactic administration for reducing lameness in broilers grown on wire flooring Poultry science (2015)
Azmanis, P. N., Wernick, M. B., & Hatt, J. M.. Avian luxations: occurrence, diagnosis and treatment. Veterinary Quarterly, 34(1), 11-21. (2014)
Zhaojun, Wang, et al. Effects of manganese deficiency on serum hormones and biochemical markers of bone metabolism in chicks Journal of bone and mineral metabolism (2013)
Crespo, Rocio, and H. L. Shivaprasad. Rupture of gastrocnemius tendon in broiler breeder hens Avian diseases 55.3 (2011)
W Muir & S Aggrey Poultry Genetics, Breeding and Biotechnology. CABI Publishing (2003)
Droual R, Bickford AA, Farver TB.. Scoliosis and tibiotarsal deformities in broiler chickens Avian Diseases (1991)
Duff, S. R., and I. A. Anderson. The gastrocnemius tendon of domestic fowl: histological findings in different strains. Research in veterinary science 41.3 (1986)
Julian, R. J. Valgus-varus deformity of the intertarsal joint in broiler chickens. The Canadian Veterinary Journal 25.6 (1984)
Thomas KW, Lowther DA. Manganese levels and the morphology of the epiphyseal plate in broilers with slipped tendons.. Poult Sci. (1976)

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"