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


Eye has Swollen Pink Tissue around It


The conjunctiva is the loose, pink lining tissue that surrounds the eyeball and lines the eye socket. Its looseness allows the free movement of the eye within the socket. This loose architecture is also what causes these tissues to swell rapidly when they are irritated or inflamed.

When the conjunctiva is swollen, it appears as a thick pink rim or mass around the eye. Possible causes include fly irritation, foreign body or foreign material, trauma, corneal ulcer, bacterial or viral infections and even cancer.

  • Code Red

    Call Your Vet Immediately, Even Outside Business Hours
    • If you notice other problems with the eye or the eye seems inflamed and painful.
    • Most eye problems are considered veterinary emergencies.
  • Code Orange

    Call Your Vet at Their First Available Office Hours
    • If the signs are very mild and the eye appears normal otherwise.
    • 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, do not allow eye problems to continue or worsen over time. Depending on the nature of the problem causing the irritation, it may look worse than it is and may rapidly respond to treatment, but when dealing with the eye, it is best not to take a chance.

Apply a fly mask and keep your horse quiet until your vet can see it.

What Not To Do

Do not use ophthalmic ointments without first discussing with your vet.

your vet's role

Your vet will first address the health of the eye and will try to determine the underlying cause for the swelling. The tentative diagnosis is conjunctivitis.

Sedation or nerve blocks may be necessary to properly examine the eye.
Questions Your Vet Might Ask:
  • Do you see any foreign material in the eye?
  • Do you see plant material or foreign material in the forelock of the mane?
  • How is your horse's attitude and appetite?
  • How long have you noticed this?
  • Have flies been bothering the eyes?
  • Has the horse had any other signs of a problem?
  • Do the horse's eyes appear different from one another?
  • Does your horse seem normal otherwise?
  • 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

further reading & resources

Author: Doug Thal DVM Dipl. ABVP