Risk factors for insidious uveitis in the Knabstrupper breed.
Authors: Kingsley Nicole B, Sandmeyer Lynne, Parker Sarah E, Dwyer Ann, Heden Sanna, Reilly Camilla, Hallendar-Edman Anna, Archer Sheila, Bellone Rebecca R
Journal: Equine veterinary journal
Summary
Equine recurrent uveitis (ERU) remains the leading preventable cause of blindness in horses, yet breed-specific risk factors remain poorly characterised outside Appaloosas, where the leopard complex spotting allele (LP) has been identified as a significant genetic risk factor. Kingsley and colleagues conducted cross-sectional ocular examinations on 116 Knabstruppers, classifying horses by clinical presentation and serological exposure to Leptospira spp., then evaluated potential associations using multivariable logistic regression whilst accounting for barn-level clustering and performing pedigree analysis on affected and control horses. Insidious uveitis affected 20.7% of the study population, with LP homozygotes demonstrating substantially elevated risk compared with genetically solid (N/N) animals (odds ratio 7.64), and horses aged 16–20 years showing greater disease odds than younger cohorts (OR 13.36), whilst pedigree analysis revealed significantly different coefficients of coancestry between affected and unaffected horses. These findings parallel the Appaloosa literature and suggest that LP genotyping should become routine for risk stratification in Knabstrupper breeding programmes and clinical management. Practitioners working with spotted and roaned breeds warrant heightened ophthalmological vigilance in middle-aged horses carrying LP alleles, though larger multi-breed studies are needed to refine predictive models and inform evidence-based counselling regarding genetic breeding decisions.
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Practical Takeaways
- •Genotype Knabstrupper horses for the LP allele to identify those at elevated risk for ERU; LP/LP horses should receive closer ophthalmologic monitoring
- •Consider age-related risk when evaluating uveitis in Knabstruppers; horses 16-20 years old warrant particular vigilance for early clinical signs
- •Breeding decisions in Knabstruppers should account for LP genotype as a significant genetic risk factor for insidious uveitis, similar to management recommendations for Appaloosas
Key Findings
- •Prevalence of insidious uveitis in Knabstruppers was 20.7% in this sample
- •LP homozygotes had 7.64 times higher odds of uveitis compared with solid (N/N) horses (p=0.04)
- •Horses aged 16-20 years had 13.36 times higher odds of uveitis compared with younger horses after accounting for LP genotype (p=0.009)
- •Coefficient of coancestry distributions were significantly different between affected cases and controls (p=0.01), suggesting genetic predisposition