Equine Eye Problems

April , 2021
 Brittany Justesen, UF/IFAS Extension Osceola County

Horses have one of the largest eyes of any land mammal. The wide lateral position of their eyes on the head means they are at risk of easily damaging the eyes. Horse eye injuries are a common problem and can occur from a variety of causes ranging from rubbing their eyes, getting poked in the eyes, and head trauma. These eye injuries can be painful for your horse and it is important to recognize eye problems early and apply the appropriate treatment for the best outcome and fastest healing.

Signs of a painful eye: 

  • Closed eye or squinting eye

  • Excessive tearing or weepy eye

  • Thick eye discharge

  • Swollen eyelid

  • Drooping eyelashes

  • Avoidance of bright light

  • Redness

A painful eye in the horse is not one of those things you should wait and see if it gets better. Since eye treatment is time sensitive it is important to call your veterinarian to have an eye exam and determine the proper treatment for your horse. During an eye exam the vet will perform tests to show pupil dilation, vision testing, and apply fluorescein stain to the eye.

Common equine eye injuries and problems:

Corneal ulcers are the most common eye condition caused by a scratch, trauma, abrasion, or foreign body that has damaged the surface of the eye. Some ulcers heal within days and others are more complex causing bacterial or fungal infections and can take longer to heal. Since the eye is painful from the corneal ulcer they can continue to rub the eye and cause additional damage. The veterinarian will diagnose if an ulcer is present using fluorescein stain dye. If an ulcer is diagnosed it is vital not to apply steroid eye ointment as this can worsen corneal ulcers. If corneal ulcers are left untreated, the ulcer can develop into something more serious.

Conjunctivitis is an inflammation or infection of the mucous membrane that surrounds the eye. This can be caused by allergies, insect hypersensitivity, or eye irritation from dust.  The rubbing to get rid of flies or irritation from the pollen causes trauma and can allow bacteria from flies and rubbing to enter the membrane. The eyeball itself is not affected, but if left untreated the horse will continue to rub the eye and can cause a corneal ulcer. Providing your horse with a fly mask will decrease issues caused by flies.

Summer sores also called habronemiasis, occur in the spring and summer months. Summer sores commonly develop in wounds, but they can occur in the corner of the eyes. Stable or face flies feed on areas of moisture like the horse’s eyes. The larva is deposited by the flies in the corner of the eye causing inflammation and irritation. In order to prevent summer sores, providing your horse with proper fly control measures and a fly mask can be very beneficial.

Uveitis is an inflammation condition of the middle layer of the eye. Uveitis can be caused by injury to the head, bacteria, a virus, parasites, or a genetic predisposition. The uveitis can be acute or recurrent, recurrent uveitis also known as moon blindness has a cloudy appearance to the eye and is the leading cause of blindness in horses.

Tumors caused by squamous cell carcinoma is a common cancer amongst horses. The tumor can start around the third eyelid or as lesions around the eyelid. This is common in horses with lack of pigment around the eye and the lesions can look like sunburn at first. It is important to destroy the tumor to maintain the eye. Prevention includes keeping horses in the stall during the day if they have pink pigment around their eye or using a sun guard fly mask to help block out sun. 

Lacerations can be caused by catching or tearing the eyelid on a sharp point or object. This can happen when horses rub their face on buckets, fence posts, or a sharp object in the stall or during turnout in pastures. Ensuring proper eyelid margin alignment during repair is essential for normal healing and correct function of the eyelid. 

 

Treatment:

The treatment required will depend on extent and cause of the eye problem. Your veterinarian will work with you to develop the best treatment plan for your horse. The goal of a treatment plan is to prevent the eye from getting worse and provide the correct medication to the eye while it heals. Depending on the severity of the eye problem your veterinarian might recommend referral to an equine ophthalmologist for more intensive diagnostic or round-the- clock treatment.

 

How to prevent eye problems:

Being vigilant with insect control and sharp hazards will help reduce the risk of eye problems. Check your pasture and barn frequently for sharp edges, nails, and hooks. Fly masks are a great tool to help prevent bugs from becoming a nuisance around the eyes and provide shade from the sun.

Checking your horse’s eyes daily for signs of pain can help catch any eye problem early on. Eye problems are an urgent matter and your veterinarian should be contacted as soon as possible to provide timely examination and treatment.

For additional questions or information contact your County Livestock Extension Agent.

Additional Resources:

https://aaep.org/horsehealth/common-equine-eye-conditions

https://aaep.org/horsehealth/equine-ophthalmology-horse-owners

 

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