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


Eye has Swollen Pink Tissue inside Corner


The third eyelid (nictitating membrane), is a pink sheet of tissue that passes over the eye like a windshield wiper,starting from the inside corner of the eyeball. It does this as a protective reflex. Growths or abnormalities of the third eyelid tend to appear as pink masses at the inside corner of the eye. Unlike dogs, horses do not develop classic "cherry eye", a blockage of the third eyelid gland.

Protrusion of the third eyelid over the eye can indicate a variety of other problems, including severe body-wide diseases like tetanus.

  • Code Red

    Call Your Vet Immediately, Even Outside Business Hours
    • If you notice any change in appearance of the eye itself.
    • If you notice other problems with the eye or the eye seems inflamed and painful.
  • Code Orange

    Call Your Vet at Their First Available Office Hours
    • If the eye appears otherwise normal.
    • The eye does not seem painful and the horse does not seem distressed.

your role


What To Do

Given the importance of your horse's sight and the wide range of conditions that could be causing this, do not allow this condition to continue or worsen over time. Take a photo and send it to your vet. Protect the eye with a fly mask until your vet can evaluate the problem.

your vet's role

Your vet will examine the eye in order to determine the structures involved, reach a diagnosis and recommend treatment. Sedation or nerve blocks may be required to properly evaluate a problem here.
Questions Your Vet Might Ask:
  • Does your horse seem normal otherwise?
  • How does it compare to the other one?
  • How long have you noticed this?
  • When did you first notice this?
  • Can you send me a photo of the problem?
  • How is your horse's attitude and appetite?
  • Has the horse had any other signs of a problem?
  • How does it compare to the other eye?
  • What are the results of the Whole Horse Exam (WHE)?

Diagnoses Your Vet May Consider

The cause of the problem. These are conditions or ailments that are the cause of the observations you make.

Very Common
Less Common
more diagnoses

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

further reading & resources

Author: Doug Thal DVM Dipl. ABVP