Ulcerative Keratitis in Donkeys

Ulcerative keratitis means there is a break in the outer surface of the cornea, the clear front window of the eye. In donkeys, this is treated much like it is in horses because the cornea is delicate, very painful, and vulnerable to rapid infection. Even a small ulcer can become much more serious if bacteria or fungi invade the damaged tissue.

These ulcers may be superficial or deep. A shallow ulcer may heal with prompt medical care, while a deeper ulcer can progress to corneal melting, descemetocele formation, or perforation. Once that happens, vision can be permanently affected and the eye may need advanced stabilization or surgery.

Donkeys can be stoic, so the eye may look worse than the animal's behavior suggests. If you notice cloudiness, tearing, squinting, or a suddenly closed eye, treat it as an emergency and contact your vet right away.

The most common trigger is trauma. Hay stems, bedding, thorns, dust, sand, fencing, and rubbing can all scratch the corneal surface. Once that protective layer is damaged, bacteria or fungi can attach to the ulcer and slow healing. In horses, fungal infection is a well-recognized complication of corneal ulcers, especially after plant material injury, and the same concern applies to donkeys.

Other contributors include foreign bodies trapped under the eyelids, abnormal eyelid shape or lashes rubbing the eye, poor tear film, and inflammation inside the eye called reflex uveitis. Equine herpesvirus can also cause corneal ulceration in equids. Some ulcers start small but become "complicated" when infection, corneal melting, or deeper stromal loss develops.

Topical steroid eye medications are a major concern if an ulcer is present, because they can worsen infection and delay healing. That is one reason your vet will usually stain the eye before choosing medications.

Your vet will start with a careful eye exam, often using sedation and pain control if needed for safety. A fluorescein stain is commonly used to highlight defects in the corneal surface. This helps confirm that an ulcer is present and gives your vet a better sense of its size and depth.

If the ulcer looks infected, deep, melting, or slow to heal, your vet may collect samples for corneal cytology and culture. Cytology can quickly show inflammatory cells, bacteria, or fungal elements, while culture may help guide antibiotic or antifungal choices. In equine ophthalmology, using both cytology and culture is often recommended for ulcerative keratitis because some serious infections are not obvious on appearance alone.

Your vet may also check for underlying problems such as a foreign body, eyelid abnormalities, tear film issues, or reflex uveitis. In more severe cases, referral to an equine ophthalmology service may be recommended for advanced imaging, subpalpebral lavage placement, or surgical stabilization.

Not every corneal ulcer can be prevented, but you can lower risk by reducing eye trauma. Check pastures, shelters, feeders, and fencing for sharp edges, protruding wire, thorny brush, and rough hay storage areas. Keep bedding and forage as dust-controlled as practical, and use good fly control to reduce rubbing and irritation around the eyes.

Daily observation matters. Donkeys often hide discomfort, so look for subtle tearing, squinting, or a change in the shine of the cornea. Catching a small injury early can make treatment shorter and less intensive. If your donkey has repeated eye problems, ask your vet to look for eyelid, lash, or tear film issues that may be setting the eye up for repeat ulcers.

Avoid using leftover eye medications unless your vet tells you to. Steroid-containing eye drops can be harmful when an ulcer is present. Prompt veterinary evaluation after any eye injury is one of the most effective ways to prevent a simple ulcer from becoming a vision-threatening emergency.