A Less Common Eye Problem

It’s not commonly known that horses, like cats, have a third eyelid. When something like a twig approaches the eye they contract the muscles pulling the eye back into the socket and the third eyelid pops over the top offering protection. However, as with any part of the body it can go wrong unfortunately.

Tilly’s owner had noticed a discharge from one eye and some intermittent swelling of the lids. When examined a mass was visible from the outer edge of the third eyelid (see picture below). A biopsy was taken to see if this was related to a worm infection (Habronema) or a tumour.

Tilly, pre-surgery showing the mass

The result of the biopsy was that a tumour was present, a squamous cell carcinoma. This can be a real issue if not caught early but fortunately Tilly’s owner was on the ball and did not delay in seeking advice. The surgery we performed to remove the third eyelid and went without any significant problems and she is all clear over 12 months later, and should stay that way. Squamous cell carcinoma is linked to ultraviolet light exposure so Tilly now wears a mask much of the time and that also helps her if she forgets that she doesn’t have the protection of a third eyelid when sticking her head into the hedge!

Carlie, showing a healthy 3rd eyelid


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