Eye Ulcers

Ulceration of the equine eye is a common condition. The position of the equine eye, its marked inflammatory response to injury and the flighty disposition of horses all predispose to the ready development of eye ulceration in these animals.

Ulceration of the equine eye typically involves the loss of the most superficial layer of the eye (cornea). This is frequently due to trauma of some description however may be due to inadequate protection as a result of eyelid dysfunction etc. Secondary infection often establishes subsequently. Eye ulcers are emergencies due to their acute, painful nature and their ability to progress rapidly. The cornear is only around 1mm thick and is very fragile. Treatment must be aggressive and initiated promptly to preserve the structure of the eye and prevent potential subsequent loss of vision should the eye rupture.

Clinical signs
Horses with ulceration of the cornea typically present with an acutely painful eye. A number of the following signs may be present:
• A watery eye with variable amounts of discharge
• Partially -completely closed eye
• Constricted pupil
• A “crater” on the surface of the eye
• Reddened conjunctivae
• Dislike of bright light
• Swelling of the eye
• A “fuzzy/blurred” appearance to the eye

A full history will often be taken by your veterinary surgeon. A thorough clinical examination will then be performed to rule out the presence of any other traumatic injuries or concurrent systemic illness that may have predisposed to the acquisition of the ulcer.

Treatment of ulcers of the eye is directed at identifying and rectifying any underlying cause of the ulceration, controlling infection and inflammation as well as promoting healing.
Generally treatment follows the 4 “A’s” rule!
Antibiotic eye drops To help control infection. Frequency of administration will be determined by your vet but may vary from twice to up to six times a day.
Atropine eye drops To control pain. Frequency of administration will vary from once every day to once every other day. Due to potential systemic side effects of this drug, your vet will advise you when to administer this medication.
Anti-inflammatory medication To make your horse more comfortable. Often a short course of bute or flunixin in feed.
(Anti-collagenase eye drops) These are usually reserved for more severe cases in an attempt to reduce the likelihood of progression of the ulcer. Your vet will advise you on these along with the frequency of administration of these should they be prescribed. Horses can become very uncooperative when administering eye medication. A number of clients(!) have overcome this through the copious use of carrots, apples and polos immediately before, during and after administration of medication. However, in some stubborn individuals a catheter system (subpalpebral lavage tube) may be temporarily placed in the horses eye to facilitate owners who are having to administer medication on a frequent basis to a difficult patient! Treats are highly advisable when using these too!

A detailed eye exam will then be performed to confirm the presence of a corneal ulcer and determine its severity.
The eye will usually be stained with special (orange!) eye drops that will highlight any area of ulceration by the
presence of a brilliant fluorescent green area. A number of other specific tests may be performed by your veterinary
surgeon to determine the presence and extent any ulceration present. The ulcer position and depth will be noted along
with any other secondary complicating factors. All other structures of the eye will be examined and treated as necessary
should any abnormalities be detected.

Simple, uncomplicated ulcers should generally heal within 7 days of treatment. Those which fail to resolve in this time frame will require more aggressive therapy and some individuals may need to be referred for further evaluation by a specialist ophthalmologist for more aggressive therapy or potential surgery.

Top 10 tips in the event of an eye injury
1) If the horse’s eyelids are shut, never try to force them open. This may further damage the eye.
2) Horses with eye injuries are often sensitive to light. By placing them in a darkened, clean stable we can instantly make them more comfortable. Alternatively applying a fly mask, specialist eye protective mask or blinkers, will help to increase their level of comfort.
3) If an “object” appears to be protruding from the eye do not try to remove it. This may be a foreign body and attempted removal may further damage the eye. However, it may be part of the inside of the eye itself that is “helping” to plug the wound.
4) Do not be tempted to use any old or previously used eye medication. Your vet will provide you with new, unopened medication and instruct you on its proper usage. Eye medication should be used within a specified time frame, after which it ceases to be effective and could potentially damage the eye.
5) Wounds to the eyelids should be reported to your vet immediately. It is important that these are treated as soon as possible to prevent any complications developing.
6) If needing to flush the eye (e.g. due to prior exposure to an irritant chemical) use clean water ONLY,. Alternatively if a proper eye wash is available this may be used.
7) Do not wipe away any discharge coming from the eye prior to any veterinary examination. Once the vet has examined the eye any further discharge should be removed. The application of petroleum jelly may reduce scalding of the adjacent skin.
8) Fly control is important in any case of eye injury to prevent further irritation and discomfort being experienced by your horse. This may take the form of a fly mask, fly repellent sprays or barrier creams.
9) Feeding from the floor may aid in reducing dust in the environment which may irritate the eye. Soaking hay is advisable where possible.
10) Horses are often inclined to rub at a painful eye. Until veterinary attention is sought ideally stay with the horse to prevent them from rubbing or, if available, the use of blinkers or a specialized eye protective face mask (if available!) is advisable.

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