Abstract: Equine metabolic syndrome (EMS) is a complex clinical disorder with both environmental and genetic factors contributing to EMS phenotypes. Estimates of heritability determine the proportion of variation in a trait that is attributable to genetics. Objective: To provide heritability estimates for nine metabolic traits associated with EMS in two high-risk breeds. Methods: Retrospective cohort study. Methods: High-density single-nucleotide polymorphism (SNP) genotype data was used to estimate the heritability (h ) of nine metabolic traits relevant to EMS in a cohort of 264 Welsh ponies and 286 Morgan horses. Traits included measurements of insulin, glucose, non-esterified fatty acids (NEFA), triglycerides, leptin, adiponectin, ACTH, and glucose (GLU-OST) and insulin (INS-OST) following an oral sugar challenge. Results: In Welsh ponies, seven of the nine traits had statistically significant h estimates that were considered moderately to highly heritable (h >0.20) including: triglycerides (0.313; s.e. = 0.146), glucose (0.408; s.e. = 0.135), NEFA (0.434; s.e. = 0.136), INS-OST (0.440; s.e. = 0.148), adiponectin (0.488; s.e. = 0.143), leptin (0.554; s.e. = 0.132) and insulin (0.808; s.e. = 0.108). In Morgans, six of the nine traits had statistically significant h estimates that were also determined to be moderately to highly heritable including: INS-OST (0.359; s.e. = 0.185), leptin (0.486; s.e. = 0.177), GLU-OST (0.566 s.e. = 0.175), insulin (0.592; s.e. = 0.195), NEFA (0.684; s.e. = 0.164), and adiponectin (0.913; s.e. = 0.181). Conclusions: Insufficient population size may have limited power to obtain statistically significant h estimates for ACTH (both breeds), glucose and triglycerides in Morgans and GLU-OST in Welsh ponies. Conclusions: This study provides the first concrete evidence of a genetic contribution to key phenotypes associated with EMS. Eight of these nine traits had moderate to high h estimates in this cohort. These data demonstrate that continued research for identification of the genetic risk factors for EMS phenotypes within and across breeds is warranted.
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The study investigates the heritability or genetic transmission of metabolic factors associated with Equine Metabolic Syndrome (EMS) in Welsh ponies and Morgan horses, providing crucial evidence of a genetic link to key characteristics of the disease.
Objective
The researchers aimed to provide estimates for heritability, that is, the proportion of variance in traits due to genetics, for nine metabolic traits linked with EMS in Welsh ponies and Morgan horses, breeds considered to be high-risk for the condition.
Methods
The investigation was a retrospective cohort study involving genotypic data of 264 Welsh ponies and 286 Morgan horses gathered using high-density single-nucleotide polymorphism (SNP) genotype data.
They measured the heritability of metabolic traits including insulin, glucose, non-esterified fatty acids (NEFA), triglycerides, leptin, adiponectin, ACTH, and glucose (GLU-OST) and insulin (INS-OST) levels after an oral sugar challenge.
Results
In Welsh ponies, seven out of nine traits had significant heritability estimates and were considered moderately to highly heritable. These included triglycerides, glucose, NEFA, INS-OST, adiponectin, leptin, and insulin levels.
In Morgan horses, six out of the nine traits had significantly high heritability, including INS-OST, leptin, GLU-OST, insulin, NEFA, and adiponectin.
Conclusions
The small population size may have limited the power to obtain statistically significant estimates for ACTH levels in both breeds, glucose, and triglycerides in Morgans and GLU-OST in Welsh ponies.
The study provides the first definitive evidence of a genetic contribution to the main phenotypes associated with EMS.
It shows that eight out of the nine traits under investigation had moderate to high heritability.
These findings support the need for further research to identify the genetic risk factors for EMS phenotypes within and across breeds.
Cite This Article
APA
Norton EM, Schultz NE, Rendahl AK, Mcfarlane D, Geor RJ, Mickelson JR, McCue ME.
(2018).
Heritability of metabolic traits associated with equine metabolic syndrome in Welsh ponies and Morgan horses.
Equine Vet J, 51(4), 475-480.
https://doi.org/10.1111/evj.13053
Morros-Nuevo A, Salt C, Pavey J, F Wainwright J, Dittmann M, Keep B, Wallis NJ, Raffan E. Behavioural susceptibility to environmental influences in obesity- evidence from a companion animal model. BMC Vet Res 2026 Jan 5;22(1):3.