Horses may be able to detect fear in humans through scent alone, according to new research showing that human emotional states can directly influence equine behaviour.
In controlled experiments, horses exposed to body odour collected from people experiencing fear were more easily startled, showed higher heart rates and were less likely to approach their handlers than when exposed to odour from people watching joyful scenes.
The findings suggest that emotional signals can pass between humans and horses through smell, with chemical compounds released in human sweat acting as an unconscious warning signal.
Testing fear and scent
The study, led by researchers at the University of Tours in collaboration with the French Horse and Riding Institute, investigated whether horses respond differently to human body odour associated with fear versus positive emotions.
Volunteers were asked to watch either frightening scenes from a horror film or joyful clips from light-hearted films, while cotton pads were worn under their arms to collect sweat. These pads were then placed near the horses’ nostrils during behavioural tests.
The horses’ responses were assessed by observing how often they approached their handler and how strongly they reacted when suddenly startled, for example, when an umbrella was opened unexpectedly nearby. Heart rate was also monitored as an indicator of emotional arousal.
Clear behavioural differences
When exposed to sweat collected from people watching frightening scenes, horses startled more easily, showed higher peak heart rates and interacted less with their handlers. No significant differences were found in cortisol levels, a hormone commonly associated with stress, suggesting the response was more immediate and behavioural rather than hormonal.
Dr Léa Lansade, one of the senior researchers, said the findings highlight how closely connected humans and horses are. “Unconsciously, we can transmit our emotions to animals, with important effects on their own emotional state,” she said.
Implications for riders and handlers
The researchers say the findings have practical implications for riders, trainers, vets and anyone handling horses. While people cannot easily control the chemical signals released through sweat, being aware of their emotional state may help reduce unnecessary stress responses in horses.
Dr Plotine Jardat, the study’s lead author, explained that arriving calm and relaxed could improve human–horse interactions, while fear or anxiety may increase the horse’s reactivity in potentially challenging situations.
Independent expert Prof Biagio D’Aniello from the University of Naples Federico II added that the study contributes to growing evidence that emotional communication can cross species boundaries. “These findings support the idea that horses can perceive human fear through smell, which may influence training, handling and everyday management,” he said.
What this means for horse welfare
The research adds to a broader body of evidence showing that horses are highly sensitive to human behaviour, body language and emotional cues. Understanding how human stress or calmness affects horses could help improve welfare, safety and training outcomes, particularly in high-pressure or unfamiliar environments.
Further research is needed to explore how these scent-based signals operate in real-world settings, but the study reinforces the importance of emotional awareness when working with horses.
