This eyelid presentation could be due to trauma, conformation, diet, or genetics. | Photo: Courtesy Robert Alexander

Q. What could cause this strange eyelid indentation? It appeared in my 2-year-old palomino filly in March 2016. My sorrel and buckskin developed it in February or March 2017. All three have been on a commercial pelleted feed for horses of all life stages since birth, along with alfalfa twice a day. They have access to free-choice pasture or coastal hay in pasture hay racks. They’ve had no problems with the eyes themselves, just the eyelids. My veterinarian has examined their eyes and done bloodwork but found nothing. Any ideas or directions would be appreciated. —Robert Alexander, via Facebook

A: This is definitely an unusual presentation. If the right eye is the only one affected, as shown above, then a traumatic injury is most likely. Sometimes after the orbital bone is fractured it can heal abnormally, although often it is still perfectly functional for the horse.

For now I am going to assume that both eyelids are similar in appearance. If the palomino were the only affected horse, it might be a conformational abnormality. Just like some horses do not have perfectly straight legs, some horses can have abnormally shaped orbits