Third eyelid dermoid in a horse.

The research article describes the case of a horse with chronic eye issues that were eventually diagnosed and successfully treated as a dermoid – a type of benign tumor – growing on its third eyelid.

Overview of the Case

• An 8-year-old Gypsy Vanner gelding, a type of horse, was brought to the University of Florida Ophthalmology service. The horse had a history of chronic, recurrent corneal ulcers in its right eye.
• Upon examination, abnormal hairs were found to be growing along the edge of the horse’s third eyelid, which is a part of the eye unique to certain animal species and generally acts as a protective layer.

Dermoid Diagnosis and Treatment

• The portion of the third eyelid where the hair was growing was surgically removed and sent off for histopathologic analysis – a microscopic examination of tissue in order to study the manifestations of disease.
• The histopathologic analysis identified the tissue with hair growth as a dermoid, a type of benign tumor that can contain fully formed tissues, often from unrelated parts of the body, including hair.
• The chronic keratitis – inflammation of the cornea – that the horse had been suffering from was then diagnosed as being secondary to the third eyelid dermoid. In other words, the animal’s persistent corneal ulcers were related to the dermoid tumor on the third eyelid.

Post-Operative Results

• Six months after the operation to remove the dermoid, the horse appeared to be cured. This suggests that the identified dermoid was likely the root cause of the persistent corneal ulcers.
• Further follow-ups would be necessary to confirm that the horse remains symptom-free longer-term and that the issue has been completely resolved.