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


Eye is Bulging or Sticking Out from Socket


A bulging eyeball is fairly uncommon, and is usually caused by pressure from behind the eyeball, most often from a tumor or other mass. This observation is more common in older horses that have a higher likelihood of cancer.

Keep in mind that the opposite eye could be abnormally recessed, making this one seem to protrude more. Eye size also ranges between different breeds. For example, Appaloosas tend to have smaller eyes. This observation is also often confused with a similar one: One eyeball that actually seems larger than the other. The two observations are distinct and the list of diagnoses is different.

  • Code Red

    Call Your Vet Immediately, Even Outside Business Hours
    • If this problem seems severe and has come on suddenly.
    • If you notice other problems with the eye or the eye seems inflamed and painful.
    • Most eye problems are considered veterinary emergencies.
  • Code Yellow

    Contact Your Vet at Your Convenience for an Appointment
    • If you consider this a chronic and relatively mild problem that is not changing rapidly.
    • If the eye appears otherwise normal.
You also might be observing
Very Common
Less Common
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your role


What To Do

In determining whether one eye is bulging, carefully compare it (standing in front of the horse) to the other eye. Consider whether the observation could actually be that one eye is larger than the other, rather than sticking out more. You can also feel the eyeballs through the upper lid with your fingertip, getting a sense of whether one or the other of the eyeballs is harder feeling.

Be sure to at some points stand right in front of the horse or look down from above to get a better perspective and to be able to compare left to right. A good vantage point to make this evaluation is from the saddle. Eyes of the same size may look different given their different color, the differences in the surrounding skin, and the different appearance of the "white of the eye." Eyes that have more white around their edges look more bulged, or larger. If you are concerned about your horse's vision, test their eyesight with the "menace response." Given the importance of your horse's sight, immediately share all of your findings and concerns with your vet.

your vet's role

Your vet will likely perform an eye exam, and use ultrasound and/ or tonometry to reach a diagnosis. Occasionally other imaging is required in order to define a mass behind the eye.
Questions Your Vet Might Ask:
  • Does your horse seem normal otherwise?
  • Do the left and right eye look the same to you?
  • Do you see an injury or foreign material in the eye?
  • Does the eye look normal otherwise?
  • Does your horse appear to be blind or partially blind?
  • Is there a difference in the colors of the left and right eye, or the color of the surrounding skin?
  • Is there any drainage?
  • Is the horse showing signs of eye discomfort like squinting or blinking?
  • Do you see grayness to the cornea or an actual area of ulceration or erosion?
  • Does the horse respond to a menace gesture?
  • 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