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Slipped Tendon


Slipped tendon is the common name for perosis, which is referred to medically as luxation of the Achilles (gastrocnemius) tendon. It is a type of leg deformity that prevents the duck from bearing weight on the affected leg. If identified early enough when ducklings are still growing, and action is swiftly taken, sometimes the condition can be reversed, or at least improved through providing support and stabilization of the hock through splinting. It may easily be confused with splay leg, however with splay leg, the whole leg deviates rather than just at the hock. Rickets may also be mistaken for slipped tendon in ducklings, however with rickets, it is caused by the long bone deformity, not tendon displacement.

Affected ducks may be seen having a difficult time walking, and continuously land with one foot on top of the other. Often ducks may present with a limp that worsens with time. In adult ducks, slipped tendons can often be misdiagnosed as sprains.


Leg deformity
Lameness which worsens with time
Leg rotation
Knee swelling
Difficulty walking
Increased time spent laying down


  • History
  • Clinical signs
  • Physical exam


MethodMethod Summary
Supplemental manganeseAdded to the diet, while ensuring not to provide excess calcium (calcium binds manganese)
SplintingMay be beneficial for early cases. A figure-of-eight bandage is applied around the hock, providing the duckling support and stabilization.
SurgeryPerformed by an Avian veterinarian, may be indicated if identified during the early stages of the condition
Anti-inflammatory medications
ManagementProtect the duck or duckling from other flock members by providing a separate area for them to not be bullied by others, but can still see and interact with them.


  • Provide feed specifically formulated for waterfowl
  • Don't feed excessive calcium, as it can cause manganese deficiency
  • Ensure adult ducks that are intended to be used for breeding purposes are receiving enough manganese in their diet, and not excessive calcium.



Risk Factors

  • Manganese-deficient diet
  • Breeder ducks with a manganese-deficient diet
  • Bone fracture not healing properly

Case Stories

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