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Key takeaways

Eye discharge in horses describes any fluid leaking from the eyes.

  • Eye discharge in horses is common
  • Occasional clear discharge that pools at the lower corner of the eye is not usually a concern
  • Discharge that looks like pus, blood, or occurs with eye sensitivity or trauma requires prompt veterinary attention
  • One common cause of discharge is environmental factors, such as allergies, dust, and flies
  • Clear discharge from irritants is normal and resolves without intervention
  • Pus-like discharge occurs with infections, uveitis, and conjunctivitis and warrants veterinary attention
  • Bloody discharge, visible physical trauma, or any signs of eye pain like squinting and sensitivity are emergencies
  • Prevention includes environmental management to reduce environmental irritants
  • Prognosis varies, but recovery is likely in most scenarios with simple underlying conditions
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A closer look: Eye Discharge in Horses

Eye discharge is most commonly caused by an environmental irritant, like dust, getting into the eye(s). The discharge is often clear in color, like tears, and may collect at the bottom of the eye. Depending on the debris, the discharge may have a slight color to it. For example, a large amount of alfalfa dust may give the discharge a slight green coloration. Small particulates can sometimes be seen within the discharge. Discharge caused by environmental irritants clears up quickly on its own once the horse is no longer exposed. Prolonged exposure to an irritant or large quantities may cause “weeping” with continual discharge. Weeping sometimes leads to a tear-line running from the eye down the face. Weeping is more concerning, and if it persists over multiple days, working with a vet to determine and remove the irritant is recommended.

The severity of eye conditions in horses varies greatly. Any new eye problems should be considered an emergency and require vet consultation. Prompt action provides the best chance of preserving vision in cases of severe conditions related to the eye.

Possible causes

Any irritating or noxious substance may cause eye discharge in horses.

Examples of common irritants include

  • Flies/insects
  • Dust
  • Pollen
  • Hay
  • Grass
  • Dirt

In addition, many eye-related conditions are associated with increased eye discharge.

Risk factors

Eye discharge varies in severity, from inconsequential to indicating an emergency. Since the eye is such a vital organ, any abnormalities need to be examined by a veterinarian. Eye conditions can rapidly progress and prompt evaluation is the best strategy for preventing permanent vision loss.

Clear eye discharge is common in horses and not always cause for concern. Tears flush irritants, like dust, from the eye. Daily, low volume discharge, does not require veterinary intervention as long as it’s clear. Instances where the horse appears to be excessively weeping, with continual discharge over the course of multiple days is cause for a veterinarian consultation. Excess drainage is often the result of a new, or increased volume, of an environmental irritant or allergy.

Discharge with a thick consistency and yellow or white coloration is usually pus and may indicate an infection.

Insects, mainly flies, perpetuate eye discharge. As the amount of discharge increases, more flies are attracted. This can lead to escalating severity of ocular discharge. Flies can transmit diseases, so this can lead to complications.

Testing and diagnosis

If medical attention is warranted, diagnostics may include:

  • Physical exam
  • Fluorescein dye on surface of eye
  • Schirmer tear test
  • Tonometry (intraocular pressure)
  • Reflex test - checking reaction time to movement in front of the eye.
  • Cell culture from the eye or surrounding tissue
  • Environmental analysis
  • Ultrasound
  • X-ray of the orbital
  • CT Scan
  • MRI

Note - A thorough eye examination may require sedatives or a local nerve block to keep the eyelid open.

Treatment varies depending on the underlying cause and may include:

  • Environmental adjustments
  • Fly masks
  • Medications
  • Surgery
  • Enucleation - removal of the eye

Similar symptoms

Associated symptoms


No Author - Writing for EQUUS Magazine
No Author - Writing for Horse Side Vet Guide
Christa Lesté-Lasserre, MA - Writing for The Horse
Agricultural Communications, Texas A&M University System - Writing for The Horse
Brett Robinson, DVM - Writing for The Horse
Katie Navarra - Writing for The Horse
Erica Larson - Writing for The Horse
University of Illinois College of Veterinary Medicine - Writing for The Horse
No Author - Writing for EQUUS Magazine

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