Equine Eye Ulcers: “It Covered Almost the Entire Width of His Eyeball”

Juliette Preston BVetMed (Hons) MRCVS from St Boniface Equine Vets discusses how to treat corneal ulcers in the eye.

One of our patients, Magic, was being led back in from the field one evening when his owner noticed a small wound to his eyelid.

Knowing that eye injuries can often become complicated, Magic’s owner was on the phone immediately and it wasn’t too long before Magic was being examined by one of our vets, Clare.

Magic was quite uncomfortable and holding his eye closed. Clare could see that the wound on his eyelid actually extended into the conjunctiva, the soft pink tissue behind the eyelid.

Additionally, the reflection on the surface of his eye was slightly irregular, whereas usually it should be a sharp, glossy reflection.

Clare applied a stain to his eye. This stain can’t stick to the smooth top layer of the eyeball (the cornea), but if the cornea has been damaged, the stain can stick to the layer underneath.

We then use a blue light to excite the stain and if the cornea has been traumatised, the ulcerated area will glow.

Unfortunately for Magic, a large ulcer covering almost the entire width of his eyeball started to glow once the stain was applied.

This confirmed Clare’s suspicion that Magic had somehow scraped both his eyelid and his eyeball while out in the field.

He was given an injection of anti-inflammatories and started on phenylbutazone or bute orally in his feed the following day.

As the damage to the cornea was so extensive, we advised to apply antibiotic drops every two hours to start with.

Luckily for Magic, his dedicated owners were out through the night to medicate his eye, and when he was re-assessed the following day the stain was repeated and showed that the ulcerated area had reduced significantly.

Magic was also a lot more comfortable, so we decided to continue his pain relief and reduce his antibiotic eye drops to only three times a day.

He was regularly re-assessed over the following two weeks and his eye ulcer continued to heal very well. He’s now back to his usual self and seems to have put the whole ordeal behind him!

Treating horses with eye ulcers

When we see a horse with an eye ulcer, we’ll almost always treat with antibiotic drops. This is because there are always bacteria present in the eye, and when the cornea is damaged the bacteria can multiply and slow the healing process, or even cause the cornea to ulcerate further.

Not all horses tolerate eye drops being applied, so sometimes we’ll hospitalise these horses and place a soft, flexible tube under their eyelid. This allows us to regularly apply eye drops from a distance without causing much distress.

We don’t use anti-inflammatories such as bute in every case as studies have shown that the use of anti-inflammatories may slow the rate of healing in the cornea. We decide on a case-by-case basis whether or not bute is appropriate depending on how painful each horse is.

Luckily for Magic his eye ulcer was quite superficial. This means that only the most outside layer of the eyeball was affected. In some more severe cases, or where an infection is present, the deeper layers of the eyeball can be affected.

For these cases, we’d recommend referral, as delicate eye surgery by a specialist may be the only option to restore sight. If surgery isn’t performed in these cases, the eyeball may rupture and the only remaining option would be to remove the eyeball.

Most horses cope very well with only one eye, but of course it may limit the type of work that the horse could do.

If you notice any changes to your horse’s eye, it’s crucial you call your vet. Eye problems can be extremely painful and may deteriorate quickly if left untreated. Most conditions of the eye can be managed easily and with good success so long as a vet can promptly assess the eye.

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