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


Pupil, One Larger than Other


Normal pupils contract or dilate depending on light levels. It is not normal for one pupil to be persistently larger than the other if each eye is exposed to the same light. This problem is indicative of eye disease or a problem with the nerve supply to the eye or the brain. If the condition is neurologic in origin, there will usually be other signs of a systemic body-wide disease.

  • Code Orange

    Call Your Vet at Their First Available Office Hours

your role


What To Do

Study your horse carefully, looking for other abnormalities and call your vet to discuss your findings and concerns.

your vet's role

Your vet does a general physical examination, looking particularly for other neurologic problems. They assess the nature of the condition, the health of the eye otherwise.
Questions Your Vet Might Ask:
  • Does your horse seem normal otherwise?
  • What are the results of the Whole Horse Exam (WHE)?
  • How is your horse's attitude and appetite?
  • How long have you noticed this?
  • How does it compare to the other one?
  • Has the horse had any other signs of a problem?

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