Uveitis and blindness in a closed herd of Equidae following leptospiral infection.
Authors: Gerras J, Young K, Roberts D, Waldman G, Salmon J H, Gilger B C
Journal: Frontiers in veterinary science
Summary
# Leptospiral Uveitis in a Multi-Species Herd: Clinical Findings and Implications for Equine Eye Health A three-year prospective study of 50 Equidae in North Carolina tracked the development of uveitis following leptospirosis exposure, with serum microscopic agglutination testing (MAT) performed at 3–6 month intervals and final assessment at 34 months. One-third of the horses (17 of 49) developed uveitis, with a striking loss of vision: whilst 59% of affected eyes retained sight initially, this dropped to just 12% by study end, demonstrating the severe and progressive nature of leptospiral-associated ocular disease. Elevated serum titres against serogroups Pomona and Bratislava correlated significantly with uveitis development (p < 0.02), yet notably, 20 of the 32 unexposed or resistant animals—including some with very high titres (>1:800)—never developed clinical eye disease despite confirmed leptospiral exposure through contaminated water sources. These findings suggest that whilst serum leptospiral titres offer diagnostic support, individual susceptibility to uveitis appears to involve genetic or immunological factors beyond simple infection exposure, warranting investigation into host factors that predispose certain horses to this blinding condition and informing future strategies for identifying at-risk animals and managing post-infection complications on affected premises.
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Practical Takeaways
- •Leptospirosis should be considered in differential diagnosis for uveitis outbreaks in herds; test serum titers and investigate water sources for environmental contamination
- •Not all exposed horses develop clinical uveitis despite seroconversion, so individual genetic/immune susceptibility likely determines clinical outcome—monitor seronegative and seropositive horses separately
- •Prognosis for vision is guarded; 88% of initially visual eyes progress to blindness, so early detection and aggressive ocular treatment are critical
Key Findings
- •34% (17/49) of horses in the closed herd developed uveitis following leptospiral infection with Pomona and Bratislava serogroups
- •Vision loss was severe: 58.8% of affected eyes were visual initially but only 11.8% remained visual at 34-month follow-up
- •Serum leptospiral titers were significantly elevated in horses with uveitis compared to non-affected Equidae (p<0.02)
- •Individual susceptibility varied markedly—some horses with very high serum titers (>1:800) never developed ocular disease, suggesting genetic or immunological factors influence pathogenesis