Corneal Ulcers in Donkeys: Cloudy Eye Emergency Signs and Care

See your vet immediately. A corneal ulcer is a break in the surface of the cornea, the clear outer layer at the front of your donkey's eye. It may start as a shallow scratch, but in some cases it deepens into the corneal tissue and becomes much more serious. Because the cornea has no blood vessels, healing can be slow and the eye is very painful.

In donkeys, we usually apply what is known from equine medicine because donkeys and horses share similar eye anatomy and many of the same urgent eye diseases. A cloudy or blue-gray eye, tearing, squinting, or a tightly shut eyelid can all point to a corneal ulcer. Some donkeys also develop reflex uveitis, which adds more pain and can make the pupil look very small.

These ulcers matter because the eye can change quickly over hours to days. Bacteria or fungi may invade the damaged cornea after trauma, and some ulcers begin to "melt," meaning the tissue softens and breaks down. Deep ulcers can rupture, which is a true emergency and may lead to permanent vision loss.

The good news is that many superficial ulcers heal well when treatment starts early and your vet can monitor progress closely. The best plan depends on how deep the ulcer is, whether infection is present, and how practical frequent medication is for your donkey and care team.

The most common cause is trauma. A donkey can scratch the cornea on hay stems, straw, thorns, dusty feed, fencing, trailer edges, or another animal. Even a small surface injury can become a true ulcer because the cornea is delicate and exposed.

Secondary infection is another major concern. In equids, bacteria and fungi can invade damaged corneal tissue after an injury. Fungal keratitis is especially important to keep in mind after plant-related trauma or when an ulcer is not healing as expected. A white or yellow plaque, worsening cloudiness, or a melting appearance can raise concern for infection.

Underlying eye disease can also set the stage. Uveitis, poor tear quality, eyelid problems, foreign material trapped under the eyelid, reduced corneal sensation, and facial nerve dysfunction may all interfere with normal blinking and healing. If a donkey keeps getting ulcers or one ulcer will not heal, your vet may look for one of these predisposing problems.

Environmental stressors matter too. Dusty housing, heavy fly pressure, bright sunlight, and rubbing from pain can all make a corneal injury worse. Prevention often means reducing trauma and irritation, not only treating the ulcer itself.

Your vet will start with a careful eye exam, often in a dim area so the eye structures are easier to see. They will look at the cornea before staining it, checking for depth, thinning, white or yellow infiltrates, a melting surface, foreign material, and signs of uveitis. Sedation may be needed in some donkeys to allow a safe, complete exam.

A fluorescein stain is the key first test for many ulcers. The dye sticks to areas where the corneal surface is missing, helping your vet confirm that an ulcer is present and estimate its size and shape. This test also helps guide treatment and follow-up. In more complicated cases, your vet may evert the eyelids to look for trapped debris, measure eye pressure, or use magnification to assess deeper damage.

If infection is suspected, your vet may collect corneal cytology or samples for culture. That is especially helpful for deep, melting, or nonhealing ulcers, and for cases where fungal infection is a concern. Referral may be recommended for advanced imaging, confocal microscopy, subpalpebral lavage placement, or surgery if the cornea is unstable.

Diagnosis is not only about finding the ulcer. Your vet is also deciding whether the eye is superficial and likely to heal with medical care, or whether it is deep, infected, or at risk of rupture. That distinction strongly affects the treatment plan, monitoring schedule, and cost range.

Not every ulcer can be prevented, but many start with avoidable trauma. Check hay quality, remove sharp wire or splintered boards, trim back thorny plants near fences and gates, and reduce dusty bedding or feed particles that can irritate the eyes. Good fly control also matters because flies increase irritation and encourage rubbing.

A well-fitted fly mask can help protect the eye from sunlight, insects, and minor trauma. This is especially useful for donkeys with sensitive eyes, a history of ulcers, or active treatment for another eye problem. Make sure the mask stays clean and does not rub the eye itself.

Watch for early signs of eye pain every day, especially after transport, turnout in brushy areas, storms, or herd scuffles. A donkey that suddenly tears, squints, or has a cloudy eye should be examined quickly. Early treatment is one of the best ways to prevent a small ulcer from becoming a deep or infected one.

If your donkey has repeated ulcers, ask your vet to look for an underlying cause rather than treating each episode as random bad luck. Eyelid problems, recurrent uveitis, poor tear film, and hidden foreign material can all lead to repeat injury and delayed healing.