Foggy Vision: Conditions That can Cloud the Equine Cornea

A number of things—some benign, some ­serious—can cause a cloudy eye. Here’s what you need to know.

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Foggy Vision: Conditions that can Cloud the Equine Eye
A blunt force or penetrating injury can cause corneal edema and cloudiness. | Photo: Dr. Richard McMullen

10 conditions that can cloud the equine cornea

Your horse’s eye is surprisingly tough yet frustratingly fragile. It can withstand an amazing number of challenges—exposure to microbes, ultraviolet light, dust and debris—but it is still vulnerable to injury and disease. One of the telltale signs that something’s wrong with it is a sudden opaque cloudiness over the cornea.

This is where your veterinarian comes in, as a number of things—some benign, some serious—can cause a cloudy eye. And any horse, from the senior with the scar on his eye due to an old corneal ulcer to the Paint with squamous cell carcinoma, can fall victim to one of these issues.

Anatomy of the Eye Surface

“Having some knowledge about the anatomy of the eye, specifically the cornea, can help us understand some of these eye issues,” says Ann Dwyer, DVM, of Genesee Valley Equine Clinic, in Scottsville, New York

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Written by:

Heather Smith Thomas ranches with her husband near Salmon, Idaho, raising cattle and a few horses. She has a B.A. in English and history from University of Puget Sound (1966). She has raised and trained horses for 50 years, and has been writing freelance articles and books nearly that long, publishing 20 books and more than 9,000 articles for horse and livestock publications. Some of her books include Understanding Equine Hoof Care, The Horse Conformation Handbook, Care and Management of Horses, Storey’s Guide to Raising Horses and Storey’s Guide to Training Horses. Besides having her own blog,, she writes a biweekly blog at that comes out on Tuesdays.

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