Melting Corneal Ulcers in Horses
- See your vet immediately. A melting corneal ulcer, also called keratomalacia, can progress within hours and may lead to corneal rupture or permanent vision loss.
- Common signs include squinting, heavy tearing, a cloudy or blue cornea, discharge, eyelid swelling, and obvious eye pain.
- These ulcers often start with trauma, then become complicated by bacterial or fungal infection and enzymes that digest the cornea.
- Diagnosis usually includes a full eye exam, fluorescein stain, and often corneal cytology or culture to guide treatment.
- Treatment is intensive and may involve frequent topical medications, pain control, atropine, a subpalpebral lavage system, and sometimes emergency surgery.
What Is Melting Corneal Ulcers in Horses?
Melting corneal ulcers in horses are severe ulcers of the cornea, the clear front surface of the eye, where the corneal tissue begins to break down rapidly. Your vet may call this keratomalacia or a melting ulcer. Instead of healing in an orderly way, enzymes from bacteria, fungi, inflammatory cells, and damaged corneal tissue digest the corneal stroma, making the eye softer, weaker, and at risk of rupture.
This is not a watch-and-wait problem. Horses with painful eyes can decline quickly, and a melting ulcer may worsen over hours to a day. Merck notes that keratomalacia is an ophthalmic emergency in horses, and complicated ulcers with melting or deep stromal loss may need specialist care and surgical stabilization.
Many cases begin as a more routine corneal injury from hay, bedding, dust, a branch, or self-trauma. Once infection or intense inflammation takes hold, the ulcer can become "melting." Because horses are also prone to fungal keratitis, especially after plant-related trauma, early treatment choices matter.
With prompt care, some horses keep useful vision and comfort. The outlook depends on how deep the ulcer is, whether infection is present, how quickly treatment starts, and whether the cornea has already perforated.
Symptoms of Melting Corneal Ulcers in Horses
- Squinting or holding the eye shut
- Excessive tearing
- Cloudy, blue, or white cornea
- Yellow, white, or thick eye discharge
- Swollen eyelids or red conjunctiva
- Visible pit, divot, or soft-looking spot on the cornea
- Small, tight pupil or signs of uveitis
- Rubbing the eye or sensitivity to light
Any painful eye in a horse should be treated as urgent, but a cloudy cornea, worsening pain, thick discharge, or a visible depression in the eye raises the concern for a melting ulcer. If your horse suddenly keeps the eye closed, resists light, or the cornea looks blue-white or uneven, contact your vet right away.
Do not put leftover eye medications into the eye unless your vet tells you to. Steroid eye medications can make corneal ulcers much worse, especially if infection is present.
What Causes Melting Corneal Ulcers in Horses?
Most melting ulcers start with corneal trauma. A scratch from hay, straw, dust, a twig, a hoof, a halter rub, or rubbing the eye can damage the corneal surface. Once that protective layer is broken, bacteria or fungi can invade deeper tissue.
In horses, infection is a major driver of corneal melting. Bacterial keratitis and fungal keratitis can both trigger release of collagen-digesting enzymes and inflammatory mediators that rapidly dissolve the cornea. Merck notes that corneal injuries in horses commonly involve bacterial and fungal contamination, and PetMD describes keratomalacia as corneal disintegration secondary to infection.
Other factors can make ulcers more likely or harder to heal. These include recurrent uveitis, eyelid problems, foreign material trapped under the eyelid, poor tear film quality, delayed treatment, or use of topical steroids when an ulcer is present. Even a small ulcer can become dangerous if it is infected or if treatment is delayed.
For pet parents, the key point is that the original injury may look minor while the deeper problem is becoming serious. That is why a horse with a painful eye needs an exam rather than home treatment alone.
How Is Melting Corneal Ulcers in Horses Diagnosed?
Your vet will start with a full ophthalmic exam. This usually includes checking the eyelids, conjunctiva, cornea, anterior chamber, pupil, and signs of reflex uveitis. Because these eyes are painful, sedation and nerve blocks may be used to allow a safer, more complete exam.
A fluorescein stain is a core test for corneal ulcers. The dye sticks to areas where the corneal surface is missing, helping your vet see the ulcer's size and shape. In a melting ulcer, your vet may also see stromal loss, corneal edema, white blood cell infiltrate, and a soft or gelatinous appearance to the cornea.
If infection is suspected, your vet may collect corneal cytology and culture or scrapings/swabs before adjusting medications. This can help identify bacterial or fungal organisms and guide treatment. In deeper or more complex cases, referral to an equine ophthalmology service may be recommended to assess whether the cornea needs surgical support.
Diagnosis is not only about naming the ulcer. Your vet is also judging depth, risk of perforation, presence of infection, and how much vision may be salvageable. Those details shape whether conservative medical care, standard intensive therapy, or advanced surgery makes the most sense.
Treatment Options for Melting Corneal Ulcers in Horses
Spectrum of Care means you have options. Here are treatment tiers at different price points.
Budget-Conscious Care
- Urgent farm-call or clinic eye exam
- Fluorescein stain and basic ophthalmic evaluation
- Topical broad-spectrum antibiotic and/or antifungal selected by your vet
- Atropine for painful reflex uveitis when appropriate
- Systemic anti-inflammatory medication such as flunixin if your vet recommends it
- Protective fly mask, stall rest, and close recheck planning
Recommended Standard Treatment
- Complete ophthalmic exam with fluorescein stain
- Corneal cytology and often bacterial/fungal culture
- Frequent topical medications, often multiple drugs
- Anticollagenase therapy to slow corneal melting, such as serum or EDTA-based protocols if your vet uses them
- Atropine and systemic pain/inflammation control
- Subpalpebral lavage system placement when frequent dosing is needed
- Serial rechecks to monitor depth, infection, and healing
Advanced / Critical Care
- Referral to an equine ophthalmology or specialty hospital
- Hospitalization and around-the-clock medication administration
- Advanced imaging or repeated specialist exams as needed
- Surgical stabilization such as conjunctival grafting, corneal grafting, or other globe-saving procedures when indicated
- Subpalpebral lavage management and intensive antimicrobial/anticollagenase therapy
- Management of perforation risk, severe uveitis, or actual corneal rupture
Cost estimates as of 2026-03. Actual costs vary by location, clinic, and individual case.
Questions to Ask Your Vet About Melting Corneal Ulcers in Horses
Bring these questions to your vet appointment to get the most out of your visit.
- How deep is the ulcer, and is the cornea at risk of perforating?
- Do you suspect bacterial infection, fungal infection, or both?
- Should we do cytology or culture before changing medications?
- How often do these eye medications need to be given, and is a subpalpebral lavage system recommended?
- Is there secondary uveitis, and how are we controlling pain safely?
- What signs mean the ulcer is worsening and I should call immediately?
- At what point would referral or surgery be the safer option?
- What is the likely cost range for the next 24 to 72 hours of care and rechecks?
How to Prevent Melting Corneal Ulcers in Horses
Not every melting ulcer can be prevented, but many start with avoidable eye trauma. Reduce exposure to sharp hay stems, dusty bedding, protruding wire, rough feeders, and low branches. A well-fitted fly mask can help protect the eyes from debris, insects, and some self-trauma in horses prone to irritation.
Prompt attention to any eye pain is one of the most important prevention steps. A small corneal scratch can become infected and start melting quickly, especially in horses. If your horse is squinting, tearing, or has a cloudy eye, contact your vet the same day rather than waiting to see if it improves.
Work with your vet to manage underlying problems that can raise ulcer risk, such as recurrent uveitis, eyelid abnormalities, or chronic irritation. Avoid using leftover steroid eye medications unless your vet has confirmed there is no ulcer, because steroids can worsen infection and delay healing.
Daily observation matters. Horses often hide early disease, but eye pain usually shows up as subtle squinting, tearing, or light sensitivity before the eye looks dramatically abnormal. Catching those early changes gives your horse the best chance for a more straightforward recovery.