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


Eye, Dark Mass Sticking Out, Iris Prolapse


A wound to the cornea can cause the fluid that fills the eyeball to leak out and the eyeball to collapse. When this happens, the colored part of the eye (the iris) can pop out through the wound.

This often appears to be a strange, usually dark colored mass sticking out of the front surface of a very inflamed (usually gray colored) eye. This observation may also be seen as as result of a tumor, a foreign body, or a deep corneal ulcer (descemetocoele).

This finding is unfortunately not as rare as it sounds. The odd appearance can be confusing to owners and caretakers. Regardless, this is a sign of a severe eye injury that must be quickly addressed.

  • Code Red

    Call Your Vet Immediately, Even Outside Business Hours

your role


What To Do

Protect your horse's eye with a fly mask or emergency bandage until your vet arrives, but ensure that nothing adheres to the surface of the eye causing irritation or additional pain.

your vet's role

If your vet diagnoses your horse with an iris prolapse, referral to a board certified equine ophthalmologist for emergency surgery should be considered. Although some general veterinary practitioners have confidence repairing this problem, corneal surgery requires specialized skills and equipment.
Questions Your Vet Might Ask:
  • How long have you noticed this?
  • How does it compare to the other one?
  • Has the horse had any other signs of a problem?
  • How is your horse's attitude and appetite?
  • Can you send me a photo?
  • Does your horse seem normal otherwise?
  • Is there any other sign of injury or an accident?
  • 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
more treatments

Author: Doug Thal DVM Dipl. ABVP