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


Abnormal Looking Object, Growth or Material Inside Eyeball


The front chamber of the equine eye (anterior chamber) occasionally houses a variety of strange looking materials and abnormal globs and blobs. Some of these may be considered "normal" and some certainly are not.

The corpora nigra (granula iridica) is a normal structure of the equine eye that acts to reduce glare. Because of its strange and variable appearance, it sometimes causes concern. Iris (and corpora nigra) cysts are relatively common, dark growths that originate from the iris and corpora nigra specifically.

Pus, blood, tumors, and other materials can also appear in the anterior chamber, and each must be assessed and treated differently. Accumulations of blood or pus can reflect problems in body-wide health, or may indicate injury to the eyeball itself.

  • Code Red

    Call Your Vet Immediately, Even Outside Business Hours
    • 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.
You also might be observing
Very Common
Less Common
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your role


What To Do

Given the importance of your horse's sight, do not allow eye conditions to continue or worsen over time. Assess your horse's general health using the Whole Horse Exam (WHE), compare the eyes to one another, and look for other signs of injury or disease. Consider whether the horse seems bothered by the condition, and whether they seem to be able to see.

Try to capture the suspected abnormality in a photo (use good light and close up view) and send it to your vet for discussion.

Look at the accompanying photo of the normal equine eye in the related media tab to help you determine the location of the problem, and as a model of what a normal and healthy equine eye should look like.

Share your findings and concerns with your vet.

your vet's role

In most cases, the diagnosis can be made by your vet using a visual exam. In some cases, they may perform an ophthalmoscopic exam to better visualize the internal structures of the eye. In rare cases, biopsy or surgical removal may be the only way to determine a definitive diagnosis.
Questions Your Vet Might Ask:
  • What exactly do you see?
  • Does the eye seem irritated?
  • Have you noticed any other signs of a problem with the horse?
  • How long have you noticed this?
  • Is the horse squinting or is there discharge?
  • How does it compare to the other eye?
  • Does your horse seem normal otherwise?
  • Does the eye seem inflamed or abnormal in any other way?
  • Does the horse respond to a menace gesture?
  • Has the appearance changed at all since you began observing it?
  • Can you send me a photo?
  • How is your horse's attitude and appetite?
  • 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.

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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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further reading & resources

Author: Doug Thal DVM Dipl. ABVP