Horses can smell fear in humans, researchers say
Tests showed horses that smelled body odour from people watching scary films startled more easily

TL;DR
- Horses react to the smell of fear in human sweat.
- Horses exposed to fearful human odor showed increased startle responses and higher heart rates.
- This suggests emotions can be transmitted between humans and horses via scent.
- Riders and handlers should be aware of their emotional state as it impacts horses.
- Volatile compounds in human sweat may serve as a warning signal to horses.