Behavioral and hormonal assessment of stress in foals (Equus caballus) throughout the weaning process.
Authors: Delank Kristin, Reese Sven, Erhard Michael, Wöhr Anna-Caroline
Journal: PloS one
Summary
# Editorial Summary: Weaning Stress in Foals — A Three-Week Assessment Weaning represents a significant physiological and psychological challenge for foals, yet the timeline for recovery and the specific behavioral markers of stress adaptation remain poorly characterised in the literature. Delank and colleagues monitored ten foals across the weaning period using continuous eight-hourly behavioral observation and fecal cortisol metabolite analysis via enzyme immunoassay, tracking changes from one day pre-weaning through three weeks post-weaning. All foals demonstrated elevated fecal cortisol levels consistent with a stress response, whilst their activity patterns shifted markedly from predominantly mobile behavior to predominantly stationary postures; notably, daytime lying decreased after an initial post-weaning increase, with compensatory increases in standing rest becoming evident. Although the hormonal and behavioral stress markers followed expected trajectories, neither had returned to baseline values by week three, suggesting that three weeks represents a minimum acclimation period rather than full recovery. For equine professionals managing young stock, these findings underscore that weaned foals warrant continued monitoring and supportive management beyond the immediate post-weaning phase—behavioral normalisation alone should not be interpreted as physiological recovery. The data also highlight the value of fecal cortisol assessment as a non-invasive tool for objectively quantifying weaning stress, which may help practitioners tailor nutrition, handling, and social grouping protocols to support individual foals through this prolonged transition period.
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Practical Takeaways
- •Weaning causes measurable stress in foals lasting at least three weeks; plan weaning during periods where extended monitoring and supportive management are feasible
- •Expect reduced activity and increased rest-seeking behavior post-weaning; provide adequate shelter, footing, and space to accommodate postural changes without forcing movement
- •Monitor for persistent behavioral changes beyond three weeks as a sign the foal may need additional environmental support, social companionship, or management adjustments to aid acclimation
Key Findings
- •All 10 foals displayed increased fecal cortisol metabolite levels indicating a distinct hormonal stress response to weaning
- •Foals shifted from mainly moving before weaning to mainly standing during the three weeks post-weaning
- •Active behavior decreased significantly while resting behavior increased, with foals initially lying more during daytime then transitioning to standing rest
- •Behavioral and hormonal changes had not returned to baseline by three weeks post-weaning, suggesting a minimum three-week acclimation period is needed