Basal Reactivity Evaluated by Infrared Thermography in the "Caballo de Deporte Español" Horse Breed According to Its Coat Color.
Authors: Bartolomé Ester, Perdomo-González Davinia I, Ripollés-Lobo María, Valera Mercedes
Journal: Animals : an open access journal from MDPI
Summary
# Editorial Summary Coat colour in horses involves more than aesthetics—genetic variants affecting pigmentation also influence temperament and stress reactivity, a phenomenon known as pleiotropy. Researchers measured basal reactivity in Spanish Sport Horses using infrared thermography of eye temperature at rest (ETR) as a non-invasive proxy for emotional state, correlating these readings with show-jumping competition results and estimating heritability to determine breeding potential. Significant differences in ETR emerged according to coat colour, sex, age and location, with heritability estimates of 0.17–0.22; importantly, horses showing lower baseline eye temperatures (less reactive phenotypes) achieved higher competition rankings, though the correlation was modest (Spearman's r = 0.11). The pleiotropic effect of coat-colour genes on reactivity was confirmed when genetic models accounting for residual variance heterogeneity produced notably higher breeding values than standard models. For practitioners selecting breeding stock, these findings suggest that coat colour represents a practical marker for temperament-related traits, and that ETR could become a measurable selection criterion for producers prioritising calmer, more consistent sport horses—though individual variation remains considerable and assessment should complement rather than replace conventional behavioural evaluation.
Read the full abstract on PubMed
Practical Takeaways
- •Infrared thermography measurement of eye temperature offers a non-invasive, objective method to assess basal reactivity in horses, potentially useful for temperament evaluation in performance selection
- •Coat color influences stress reactivity and performance outcomes; consider this genetic factor when breeding for competition horses with appropriate temperaments
- •ETR has sufficient heritability (0.17-0.22) to warrant inclusion in selective breeding programs targeting improved behavioral traits in sport horse populations
Key Findings
- •Eye temperature at rest (ETR) differed significantly by coat color, sex, age, location, and breed-group factors
- •Weak but significant correlation (r=0.11, p<0.05) between lower ETR and better Show Jumping rankings
- •Heritability of ETR ranged from 0.17-0.22, with higher breeding values in models accounting for genetic groups and residual variance heterogeneity
- •Coat color demonstrates a pleiotropic effect on basal reactivity, making ETR suitable for genetic selection in breeding programs