Equine Eye Disease

Horses have the largest eyes of any land animal. These huge eyes make it easier to spot predators but also make it easier to become injured and then diseased. Horses are also prone to equine eye disease, especially Appaloosas or horses with Appaloosa spotting. According to Horse Owner's Home Veterinary Handbook, horses can get diseases of the retina, eyelid or the entire eye.

  1. Symptoms

    • Horses can be suspected of having an eye disease when they squint even in the dark, have excessive discharge from the eye, cannot close their inner eyelid, have mucus present on the eyeball, have a cloudy or bluish look in the pupil or a black expression as if the horse is awake yet removed from the world. This blank expression is thought to be a result of pain.

    Diseases of the Eyelid

    • Horse diseases of the eyelids include entroption, where the eyelashes are brushing against the eyeball; eyelid melanomas and sarcoids--small tumors that can appear singly or in groups that can be either benign or cancerous. The Horse Owner's Home Veterinary Handbook claims the most common horse eyelid disease is squamous cell carcinoma, which is almost always cancerous and often appears on older horses with white eyelids.

    Eye Diseases

    • Horse diseases of the eyes include three types of glaucoma (congenital, primary and secondary from the result of a previous illness); three types of equine recurrent uveitis or "moon blindness" (classic, posterior or insidious); congenital stationary night blindness, which is a genetic disease of the retina and anterior segment dysgenesis, a genetic disease causing the front part of the eye to never grow in a normal fashion.

    Causes

    • Eye diseases in horses can be caused by genetics, but they are mostly caused as a result from a previous injury to the eye, cornea or eyelid. Previous bacterial or fungal infections of the eye or eyelid can also make a horse more prone to catching eye diseases. However, the cause for primary glaucoma is unknown, because a horse develops glaucoma even without previous infection or injury to the eye.

    Breeds

    • According to Dennis E. Brooks, DVM, Ph.D., horses from certain breeds are prone to genetic eye conditions. These include American saddlebreds, Appaloosas, Arabians, Belgians, Percherons, Tennessee walking horses, miniature horses, thoroughbreds, Morgans, Morabs, Quarabs, quarter horses, quarter ponies, Rocky Mountain horses, Pony of the Americas (POA), Paso Finos, standardbreds, warmblood or sporthorse breeds, such as the Trakehner, and any mules that had a horse parent of those breeds.