Corneal Ulcers in Horses

Corneal Ulceration in Horses

Corneal ulcers -- injuries to the outermost layer of the eye -- are usually the outcome of some type of trauma to the eye. It may have come about as the result of running into something, violent contact with another horse, a foreign object entering the eye, fungus or bacteria in the surrounding environment, and harsh dust entering the eyes. All of these can be considered traumatic incidents.

Once the eye has an ulcer, it can easily become infected, and these infections have the potential to turn a corneal ulcer into a serious health issue, sometimes breaking down the corneal tissue and leading to a defect of the eye that needs more invasive treatment than if it had been given immediate treatment.

Symptoms and Types

  • Redness in the eye
  • Severe eye pain (squinting or closing the eye)
  • Swollen eye lids
  • Tears running down the face
  • Eye infection(s)
  • Inflamed lining of the eye (conjunctivitis)
  • Dull corneal surface (i.e., cloudy in appearance)
  • Blood vessel development through the cornea
  • Ocular discharge


Corneal ulcers are often due to eye trauma, whereby foreign objects come into contact with the eye. Other secondary issues include bacterial, viral, and fungal infections.


Your veterinarian will perform a thorough ophthalmological exam on your horse, taking into account the background history of symptoms and possible incidents that might have led to this condition. A fluorescein stain, a non-invasive dye that shows details of the eye under light, will be used to identify the presence of an ulcer and its location on the eye’s surface. Fluorescein stain adheres to the underlying ocular connective tissue that is exposed by the ulcer, staining this area bright green. If there is no ulcer, no stain will adhere to the eye.

An ulcer, after staining, should be easily visible, as well as the side effects to the condition itself. If it appears that an infection is present, your veterinarian will need to take samples from the cornea by scraping away some of the tissue for laboratory testing. Any discharge or fluid will also be collected for testing. A specific diagnosis is essential, as not all drugs are appropriate for treating an injured eye, and some may in fact do more harm.

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