What you see. The starting point for addressing any equine health related issue is your observation.


Can't Seem to Move or Bend Hind Limb, Seems Locked


This is a fairly common, but visually shocking observation. It is usually caused by a mechanical abnormality of the hind-limb passive stay apparatus, the mechanical catching and lodging of the patella on the medial trochlear ridge of the femur called "locking stifle", "upward fixation patella" But there are other causes too.

With the stifle locked, the hind limb is rigidly immobilized. When a horse tries to walk forward, the affected limb trails stiffly behind. Often the fetlock folds and knuckles over as part of this syndrome. If the horse can bear weight but not advance the limb, the rule-out diagnosis is a locking patella. The good news is that this condition is reversible and usually fairly easy to correct and manage.

In contrast, horses with fractures and other more serious injuries may look like this, but generally they will refuse to bear weight on the affected limb.

  • Code Red

    Call Your Vet Immediately, Even Outside Business Hours
You also might be observing
Very Common
Less Common
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your role


What To Do

Perform the Whole Horse Exam, paying particular attention to heart rate, attitude and appetite and rectal temperature. Look carefully at the affected hind limb. Do you notice swelling, a wound or hair loss that might indicate trauma. Take digital pulse of all 4 limbs. Try to walk the horse forward. What happens?

your vet's role

Your vet assesses general health and the affected limb. The vet knows how to differentiate a locked stifle from other conditions. In most cases, the locked stifle may be unlocked by pushing the patella to the inside (medially). Radiographs, nerve blocks and other diagnostics may be needed in some cases.
Questions Your Vet Might Ask:
  • Has your horse done this before?
  • When did you first notice this problem?
  • Describe the type of exercise and riding that you do with your horse.
  • Has the feed, management, rider, riding style, or tack changed?
  • What are the results of the Whole Horse Exam (WHE)?

Treatments Your Vet May Recommend

A way to resolve the condition or diagnosis. Resolving the underlying cause or treating the signs of disease (symptomatic treatment)

Very Common
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Author: Doug Thal DVM Dipl. ABVP