Horses Blink Less, Twitch Eyelids More When Stressed

How can you tell when a horse is feeling stressed? Its all in the eyes and the way their eyelids twitch University of Guelph researchers have discovered.
A horse will blink less and twitch its eyelids more when its under mild stress the research team found a new finding that could offer handlers a simple easytospot sign their animal is becoming agitated.
The study published in the journal Animals is thought to be the first to reveal the significance of eyelid twitches as an indicator of stress says Prof. Katrina Merkies the studys lead author.

With humans we already know our blinking changes when we are under pressure. Some studies have shown we blink more when agitated while others found we blink less. We wanted to see if horses blink rates change too said Merkies a professor in the Department of Animal Biosciences at the Ontario Agricultural College.
When we train horses we specifically teach them to suppress their stress responses because we dont want horses to react when they are startled or nervous. But even if theyve learned to suppress their reaction it doesnt actually decrease the stress they feel she said.
While stress can be measured through heart rate monitors or blood cortisol levels Merkies and her team wanted a noninvasive measurement so they decided to test whether a horses eyes could offer clues.
They recruited 33 horses of various breeds from three riding lesson facilities in eastern Ontario and exposed them to three mildly stressful scenarios.
In the first a ball was thrown in