Seasonal pattern of cortisol fluctuation in horsehair samples from three different body areas: A year long study.
Authors: Skurková L, Matulníková L, Peťková B, Florian M, Slivková M, Lešková L, Mesarčová L, Kottferová J
Journal: Journal of equine veterinary science
Summary
# Editorial Summary: Seasonal Cortisol Patterns in Equine Hair Understanding whether stress biomarkers fluctuate seasonally could help practitioners interpret hair cortisol concentrations (HCC) more accurately as a measure of chronic stress in horses. Researchers collected hair samples quarterly over 12 months from 12 horses aged 1.5–30 years, sampling from the mane, tail, and carpal region of the forelimb, then analysed cortisol concentrations using ELISA. Clear seasonal variation emerged, with August samples showing the highest cortisol levels (mean 18.63 ng/ml) and April the lowest (10.05 ng/ml)—a pattern that held regardless of which body area was sampled. Whilst sampling location generally did not influence results, winter samples did show minor differences between mane and leg sites, and between tail and leg sites, though mane and tail samples remained comparable. The authors appropriately note that their modest sample size and the multifactorial nature of seasonal stress warrant cautious interpretation, but these findings suggest that practitioners should account for season when using HCC as a stress assessment tool—an April reading, for instance, would not be directly comparable to an August one without considering this temporal context.
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Practical Takeaways
- •Hair cortisol analysis can detect seasonal stress patterns in horses, with summer months showing elevated chronic stress markers compared to spring
- •Hair samples can be collected from any body area (mane, tail, or leg) for cortisol analysis without affecting result validity, simplifying collection logistics
- •Baseline cortisol values should account for season when using hair analysis for individual stress assessment; April values are naturally lower while August values are naturally higher
Key Findings
- •Horsehair cortisol concentrations show significant seasonal variation with highest levels in August (18.63 ng/ml) and lowest in April (10.05 ng/ml)
- •Seasonal pattern follows the sequence August > November > January > April (F=50.28, P<0.001)
- •Hair sampling location (mane, tail, carpal area) does not significantly affect cortisol concentrations overall (P=0.308)
- •No correlation found between horse age and hair cortisol concentrations