Twitched horses actually displayed reduced behavior issues and heart rates, indicating less distress, upon the second exposure to the twitch, even nearing baseline measurements, researchers found. | Photo: Courtesy Katelyn Gutwein

To better determine how nose twitching influences horses, Ahmed Ali, BVSc, MS, of Michigan State University’s (MSU) Department of Animal Sciences as well as Cairo University’s Animal Management and Behaviour Faculty of Veterinary Medicine, in Egypt, compared horses’ behaviors and heart rate with and without twitch application. Camie Heleski, PhD, animal behavior and welfare instructor at MSU, presented the results on his behalf at the 11th annual International Society of Equitation Science conference, held Aug. 6-9 in Vancouver, British Columbia.

In their study, the team performed an aversive procedure—clipping the hair on the inside of a horse’s ear—in eight Arabian horses that had never had their ears clipped or been twitched. The horses were randomly assigned to be clipped with or without a twitch, followed by the alternate treatment, followed by a second ear clipping while twitched. The team recorded the horses’ behaviors, heart rate, heart rate variability (slight rate changes from beat to beat), and the time it took to clip the ears.

The untwitched horses had the highest heart rates and lowest heart rate variability (both indicators of stress), the most behavioral indications of aversion (e.g., vigorous head movements), and took the longest time to complete the ear clipping procedure, compared to twitched horses, the team said