A retrospective survey of equine ocular diseases evaluated at a referral hospital in Ontario (2011 to 2021).

Abstract

Objective: Our objective was to investigate the demographics and prevalence of ocular disease in a large referral population of horses in Ontario over a 10-year period.

Animals and procedure: A retrospective analysis of medical records for 283 horses evaluated by Board-certified veterinary ophthalmologists at the Ontario Veterinary College (Guelph, Ontario) was conducted. Signalment and ocular disease were recorded.

Results: The 3 most common ocular abnormalities identified were uveitis (43.7%, 123 horses), ulcerative keratitis (42.0%, 119 horses), and cataract (25.1%, 71 horses). Uveitis was most often secondary to other ocular disease. Middle-aged horses (5 to 15 y) had a lower proportion of ulcerative keratitis than young horses (0 to 4 y) and older horses (16 to 35 y) (P = 0.015). Older horses were more likely to be diagnosed with glaucoma than were young and middle-aged horses (P = 0.022). Thoroughbred was the most common breed referred. Warmbloods were significantly less likely to receive a diagnosis of uveitis compared to other breeds (P = 0.05). Adnexal disease and neoplasia were both more prevalent in draft breeds compared to other breeds (P < 0.001).

Conclusion and clinical relevance: For the first time, the most prevalent ocular diseases and breeds referred for ocular disease are reported for horses in eastern Canada. This study serves as a reference for practitioners and sets a baseline for future studies.