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


Eyes are Bothered by Flies


Flies of different types love to bother horse eyes, and their presence commonly causes eye irritation. Flies can also transmit certain bacterial and parasitic diseases to the eyes of horses.

Stable Flies are a seasonal problem in most areas and are usually worse in summer and fall. At certain times of year (fall), Stable Flies are particularly drawn to equine eyes, especially the corners of the eye. They cause irritation that results in tearing and squinting and predispose to the development of corneal ulcers and conjunctivitis.

No-See-Ums (gnats, Culicoides) can sometimes feed around the eyes at night, and can cause severe irritation and itchiness.

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    Contact Your Vet to Obtain Useful Advice & Resources

your role


What To Do

Given the importance of your horse's sight: if you notice a problem with the eyes or cannot find a way to protect them from flies, do not allow this condition to continue or worsen over time. Assess the eyes carefully. If they seem irritated, red, swollen, or if there is tearing or discharge contact your vet to discuss your findings and concerns.

It is helpful to identify the type of flies that are bothering the horse's eyes. Take a photo of the flies and the situation and share it with your vet.

Prevention is key. This starts with a good fly control and manure management program at your facility. Apply a fly mask. In some cases, applying a fly repellent ointment around the eyes may be helpful.

What Not To Do

Do not apply topical repellents too close to the eyes. They can cause irritation and potentially eye damage. Fly repellent ointments may melt and run into the eyes, causing irritation. Apply conservatively.

your vet's role

Your vet may know the insect species and their biology and may have recommendations on how to control or decrease the fly population at your facility, so to prevent the development of more serious eye problems.
Questions Your Vet Might Ask:
  • Do the eyes appear irritated?
  • Is there discharge or squinting?
  • Does the horse wear a fly mask?
  • What is being done to manage the fly problem?

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