Behavior changes may be an early clue to vision loss in horses

A new article from The Horse highlights a deceptively simple clinical point: vision problems in horses can show up first as behavior changes, not obvious eye disease. In the May 2, 2026 piece, Christa Lesté-Lasserre reports that equine ophthalmologists Nicole Scherrer of the University of Pennsylvania’s New Bolton Center and Richard McMullen of the University of Zurich caution that signs such as new spooking, jump refusals, difficulty with light-to-dark transitions, unusual head positioning, bumping into objects, squinting, or even getting disoriented in unfamiliar settings can all raise suspicion for impaired vision, especially when the pattern is worse on one side. The article also underscores that some horses with significant ocular disease may show few outward signs at all. (thehorse.com)

Why it matters: For equine veterinarians, the takeaway is less about any single “red flag” and more about pattern recognition and early workup. AAEP notes that eye problems are common in horses and that prompt examination is important to preserve vision, reduce pain, and prevent recurrence. Cornell ophthalmology guidance similarly emphasizes that history, distant observation of visual behavior in different lighting conditions, neuro-ophthalmic testing, and a full ophthalmic exam are central to determining whether behavior changes reflect ocular disease such as corneal disease, uveitis, cataracts, corpora nigra cysts, or other pathology. (aaep.org)

What to watch: Expect continued emphasis on earlier referral for equine eye exams when pet parents or trainers report subtle, unilateral, or lighting-dependent behavior changes. (aaep.org)