Estimates of heritability for ossification of the cartilages of the front feet in the Finnhorse.
Authors: Ruohoniemi M, Ahtiainen H, Ojala M
Journal: Equine veterinary journal
Summary
# Editorial Summary: Heritability of Cartilage Ossification in Finnhorses Cartilage ossification in the feet is particularly prevalent in coldblooded horses, yet breeding selection for this trait has been limited by sparse heritability data. Ruohoniemi and colleagues analysed dorsopalmar radiographs and four-generation pedigrees from 964 Finnhorses (aged ≥2 years), grading ossification at the cartilage base and total ossification on a 0–5 scale, then estimating heritability using restricted maximum likelihood analysis. Heritability estimates for total ossification ranged from 0.31 to 0.50 depending on which cartilage and foot was assessed, with slightly higher heritability for ossification at the cartilage base; notably, females demonstrated significantly greater ossification progression with age than males, particularly in medial cartilages. These relatively high heritability coefficients, combined with strong genetic correlations between contralateral feet and between medial and lateral cartilages, indicate that both feet and both cartilages share similar genetic predisposition to ossify. For breeding programmes and clinical management, these findings suggest that selection against severe ossification is feasible, and that assessment of one cartilage or foot may provide insight into the whole-foot phenotype; practitioners should also recognise the sex-age interaction, as mares warrant closer monitoring for progressive ossification and may warrant different breeding consideration than stallions.
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Practical Takeaways
- •Breeders can use these heritability estimates to implement selective breeding programmes to reduce cartilage ossification in Finnhorses, as the trait shows substantial genetic control (h² = 0.31–0.50)
- •The sex and age differences in ossification prevalence should inform radiographic screening protocols and breeding decisions, particularly for female horses entering breeding programmes
- •The similar genetic tendency for ossification across both cartilages and both front feet means that assessment of one limb provides predictive information about genetic predisposition in other limbs
Key Findings
- •Heritability estimates for total ossification ranged from 0.31 to 0.50 across different cartilages and feet, indicating moderate to high genetic influence on the trait
- •Females demonstrated significantly more ossification than males, with this difference increasing with age, particularly in medial cartilages
- •High genetic correlations were found between medial and lateral cartilages within feet and between corresponding cartilages in right and left feet, suggesting coordinated genetic control
- •Heritability estimates were slightly higher for ossification at the base of cartilages compared to total ossification, indicating selective genetic influence on different ossification patterns