Overview
- The peer-reviewed paper was published January 14, 2026 in PLOS One by researchers in France.
- Participants provided armpit sweat after scary, joyful, and neutral video clips, and 43 female horses were exposed to the odors via pads positioned near their nostrils.
- The team minimized contamination by having only donors handle the pads and by freezing samples to preserve odor compounds.
- Horses smelling fear-related samples startled more, were less willing to approach people, and showed reduced investigation of a novel object.
- Physiological measures showed higher heart rates during startle tests, saliva cortisol was recorded as a stress biomarker, planned follow-up work will identify the compounds and test other emotions, and an independent expert cautioned that horses use multiple senses in real settings.