Understanding Equine Stress:

Even though many horse owners can tell when their horse is tense, horses can be good at covering up their stress, especially if horses are well-trained. Researchers from University of Guelph in Canada have investigated how horses react when under mild pressure, and they have have found an easy way for all horse owners to see if their horse is stressed or scared of something.

How Can You Tell if a Horse is Stressed?

• Blinking Patterns: Stressed horses tend to blink less frequently and may show irregular eyelid contractions.
• Research by Professor Katrina Merkies: This finding was based on a study at the University of Guelph, observing horses under mild stress.
• Easy Monitoring: Horse owners can monitor their horses’ stress levels by noting changes in blinking behavior.

Horses can cover up stress

When we train horses, we teach them to suppress their stress response because we do not want the horses to react when they are tense or nervous. Even though they have learned to hide their reactions, it does not mean they feel less stressed.

– In humans, we know that the way we blink changes when we are under pressure. Some studies show that we blink more when anxious, while others show that we blink less. We wanted to see if the way horses blink also changed when stressed, says Professor Katrina Merkies, an Animal Biosciences professor from the University of Guelph.
– Look at the horse’s eyes and how the eyelid contracts: the horse will blink less and close the eyelid differently when under stress.

An uncomplicated stress monitor

Stress can be measured through a heart monitor or blood tests, but Merkies and her colleagues wanted to find an uncomplicated method everyone involved with horses could use. Therefore, they decided to see if the horse’s eyes could provide the answer.
They observed 33 horses of different breeds from various riding schools. All the horses were subjected to three different mildly stressful experiences. First, the horses were presented with a ball thrown right in front of them to scare them a little. In the next experiment, the horse was separated from its herd, so it could not see the other horses. Last but not least, the horse’s food was withheld for three minutes at feeding time while the other horses in the herd were fed.

Researchers filmed horses to observe stress

The researchers filmed the horses to observe changes in movement in the eyes and ears and signs of general restlessness. They found that withholding food was the most stressful thing for the horses, while the exercise with the ball and separation from other horses elicited very little response.
– It is important to remember that riding school horses are used to being a little frightened or surprised every day and are separated from the other horses daily. Food, on the other hand, means a lot to horses, and withholding food was a wholly new and surprising experience, and that may be why they were stressed, she said.

Horses blinked less when stressed

When the researchers evaluated the videos of the horses’ eyes when food was withheld, they found that the horses blinked less but that they contracted the eyelid a bit in jerks. On average, the horses blinked five times a minute when stressed, compared to 8-9 times a minute when they were relaxed. When food was withheld, and the horses were under the most pressure, the contractions of the eyelid increased from two times per minute to up to six times per minute. During the other tests, there was no difference in how often the horse contracted the eyelid.
The researchers hope these findings will give horse owners and trainers a tool to perceive the horse’s mood and feelings. It is not a method that tells us everything, but it is a tool we can put in our toolbox and use to understand our horses better.