Injuries and Diseases in the Horse’s Eye

Injuries and Diseases in the Horse’s Eye Article provided by the team at XLEquine

Horses’ eyes are easily damaged as their position on the head means they are at risk when the horse grazes near hedges or brushes past trees. Here the XLEquine team talk about diseases, signs and treatment.

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A painful eye in the horse is a veterinary emergency. Most conditions are easily treated, but if untreated, severe disease can occur, which may threaten the horse’s sight in the future.

Signs and Investigation

• A painful eye will usually have swollen eyelids, drooping eyelashes, excessive tearing and blinking. Occasionally there will be obvious problems, perhaps a foreign body, such as a thorn, stuck into the eye.
• Horses have a very strong blink reflex, so the vet may need to sedate the horse and desensitise the upper eyelid to fully examine the eye.
• Initially, the bony structures around the eye will be examined for any obvious fractures. The upper, lower and third eyelids will then be checked for foreign bodies, such as hay seeds, stuck underneath. Any obvious wounds, lacerations or foreign bodies on the eye surface (cornea) will be noted and the inside of the eye will be checked for inflammation (seen as cloudiness) or problems at the back of the eye. This examination will require a good torch and an ophthalmoscope.
• The vet will then usually apply a fluorescent stain to check for damage to the cornea. Any areas of damage will stain fluorescent green and these are called ulcers.
•  Any wounds around the eyelids should be examined and stitched if possible.

Diseases and Treatments

• The most common painful eye conditions are corneal ulcers and uveitis.
• Corneal ulcers or scratches are easily diagnosed using a fluorescent green stain. These must be treated urgently as they can become severely infected, resulting in the cornea ‘melting’ away and the eye rupturing. Treatment usually requires antibiotic eye drops and serum eye drops to encourage healing and prevent ‘melting’. The horse will usually be given anti-inflammatory drugs for pain relief. Treatment for corneal ulcers is relatively inexpensive and usually results in a complete cure within a week or two.
• Uveitis is inflammation of (usually) the internal part of the eye, which causes intense pain. The pupil becomes smaller, and there is usually cloudiness in the cornea or front of the eye. Uveitis can occur after corneal ulceration but is more often an immune response. This means that uveitis can recur and each episode may cause more severe changes to the horse’s eye, such as cataracts or a permanently shrunken pupil. Treatment involves steroid eye drops, atropine eye drops to open the pupil and injectable or in-feed pain killer anti- inflammatories. It is vital to check for corneal damage before starting steroid eye drops as these can worsen ulcers.
• If there is a foreign body stuck into the eye itself, or a deep cut to the cornea, urgent surgical treatment may be required.

Difficult Cases

It is very important to ensure that the horse receives prescribed medication, as treatment failure can result in loss of sight or even necessitate removing the eye. Despite our best efforts, some horses with severe uveitis flare-ups will need to have their eye removed for their welfare.

If it is very difficult to put in eyedrops, then a subpalpebral lavage system can be inserted. This is a tube that carries medication to the eye surface from the withers area, meaning treatment can be continued without touching the horse’s head

Summary

• Swollen, half-shut eyes with excessive tearing and blinking are very painful.
• Treatment of a painful eye is classed as a veterinary emergency.
• Most corneal ulcers are easily treated and should heal within a short time period.
• Inflammation of the eyeball is treatable but can result in repeated flare ups and occasionally even a permanently painful, blind eye.
• Some conditions may require urgent referral to a specialist centre.

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About XLEquine

XLEquine is a group of 35 mixed veterinary practices spanning the length and breadth of the UK. They work together to share experience, knowledge, ideas and skills in order to define and deliver the highest standards of equine health, care and welfare.