SNP-Based Heritability of Osteochondrosis Dissecans in Hanoverian Warmblood Horses.
Authors: Zimmermann Elisa, Distl Ottmar
Journal: Animals : an open access journal from MDPI
Summary
# SNP-Based Heritability of Osteochondrosis Dissecans in Hanoverian Warmblood Horses Osteochondrosis dissecans (OCD) remains a significant developmental orthopaedic disease affecting performance horses, yet understanding its genetic basis has been hindered by the practical limitations of traditional pedigree-based heritability estimates. Zimmermann and Distl employed SNP genotyping data from 446 Hanoverian warmbloods, utilising 1.6 million imputed genotypes analysed through genomic restricted maximum likelihood (GREML) methods whilst accounting for regional linkage disequilibrium patterns in the equine genome. Their findings revealed substantial additive genetic contributions to OCD across different joints: fetlock OCD showed heritability of 0.41–0.43, hock OCD 0.62–0.63, and stifle OCD 0.23–0.25—notably capturing greater additive genetic variance than previous pedigree-based estimates in the same population. Critically, the highest heritability estimates emerged when GREML family models incorporated genomic relationship matrices weighted for linkage disequilibrium, suggesting that joint-specific genetic architecture varies considerably and that hock OCD has particularly strong heritable components. For breeding programmes and stud book management, these robust SNP-based estimates provide more reliable guidance than pedigree analysis alone, supporting selective breeding decisions and justifying investment in genomic testing for this costly developmental disease, particularly where phenotyping remains resource-intensive.
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Practical Takeaways
- •Osteochondrosis dissecans in hocks shows strong genetic control (h²=0.62-0.63), making selective breeding a viable strategy to reduce hock OCD in Hanoverian warmbloods
- •Fetlock and hock OCD have moderate-to-high heritability; breeding away from affected animals and carriers identified through genomic testing could reduce incidence more effectively than pedigree-based selection alone
- •Stifle OCD shows lower heritability (h²=0.23-0.25), suggesting environmental and management factors play a larger role—focus on growth management, exercise protocols, and nutrition alongside genetic selection
Key Findings
- •SNP-based heritability estimates for fetlock osteochondrosis dissecans were 0.41-0.43, substantially higher than previous pedigree-based estimates in the same population
- •Hock osteochondrosis dissecans showed the highest heritability at 0.62-0.63, while stifle osteochondrosis dissecans was lowest at 0.23-0.25
- •GREML analysis accounting for linkage disequilibrium patterns and family relationships provided the most consistent and robust heritability estimates
- •SNP-based genomic methods captured a larger proportion of additive genetic variance compared to traditional pedigree analysis