Determining whether your horse is stressed can be as simple as looking into his eyes.

According to a Canadian study, horses in challenging situations blink less often than do those who are calm.

Researchers at the University of Guelph videotaped 33 horses in four different situations: standing in a familiar paddock with a herdmate; having feed withheld at the normal mealtime; being visually separated from their herdmate; having a ball suddenly thrown onto the ground in front of them. All the horses were also fitted with heart rate monitors that collected data every five seconds during the three-minute study periods.

When researchers analyzed the videotapes for eyelid activity, they found the horses blinked an average of eight to nine times per minute during calm periods, when standing in a familiar paddock. However, when their feed was restricted, they were separated from their peers or they were startled, the horses blinked less often. During periods of feed restriction and separation, the horses blinked about five times per minute, and when the ball was thrown to startle them, they blinked about four times per minute.

In addition, the data showed that the horses’ heart rates increased and the muscles around their eyes twitched more frequently during the feed- deprivation periods.

The researchers say all of this information can be used as a noninvasive method of determining whether a horse is stressed.

Reference: “Eye blink rates and eyelid twitches as a non-invasive measure of stress in the domestic horse,” Animals, August 2019 

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