Inheritance of equine sarcoid disease in Franches-Montagnes horses.
Authors: Christen Garance, Gerber Vinzenz, Dolf Gaudenz, Burger Dominique, Koch Christoph
Journal: Veterinary journal (London, England : 1997)
Summary
Equine sarcoid is a common neoplastic condition affecting horses worldwide, yet the genetic basis of susceptibility remains poorly understood, limiting opportunities for informed breeding decisions. Researchers examined clinical examination records and pedigree data from a large cohort of Franches-Montagnes horses, subjecting the disease trait to segregation analysis and evaluating five competing inheritance models to identify the most probable mode of transmission. Polygenic inheritance emerged as the best explanation for variation in sarcoid susceptibility, with an estimated heritability of 21% on the liability scale; whilst a single major gene effect—potentially involving equine leukocyte antigen alleles—could not be entirely excluded, the data did not support such a model. Although these findings indicate that breeding values could theoretically be calculated for sarcoid resistance, the authors highlight significant practical barriers to implementing such a tool in a multifactorial condition characterised by incomplete penetrance and environmental influences. For practitioners advising on breeding programmes, this research suggests that whilst genetic selection for reduced sarcoid susceptibility may be possible, it would yield modest gains and must be balanced against other traits of economic or welfare importance.
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Practical Takeaways
- •Sarcoid susceptibility cannot be simply selected against through breeding as it involves multiple genes; selection decisions should consider this polygenic nature
- •The moderate heritability (21% on liability scale) suggests environmental and management factors play a substantial role in disease expression, offering practical intervention opportunities
- •Genetic testing for single markers is unlikely to be useful for sarcoid prediction; focus should remain on clinical monitoring and lesion management rather than genetic screening
Key Findings
- •Susceptibility to equine sarcoid disease is best explained by polygenic inheritance rather than single major gene inheritance
- •Heritability of sarcoid disease estimated at 8% on observation scale and 21% on liability scale
- •Major gene effects such as equine leukocyte antigen alleles are unlikely but cannot be completely excluded as contributing factors
- •Breeding value estimation for sarcoid disease is theoretically possible but practical implementation in this multifactorial condition is questioned