Researchers Study Horses' Startle Response to Novel Objects

"He has a great temperament." You might have heard an owner or trainer say these words when describing a horse, but how do we really define temperament?

According to Jeannine Berger, DVM, Dipl. ACVB, of the San Francisco Society for the Prevention of Cruelty to Animals in California, one of the most useful and consistent indicators of equine temperament is a horse's novelty response, or how he handles or copes with new objects or situations. She presented the results of a recent novelty response study she and colleagues conducted on adult horses at the 9th Annual International Society for Equitation Science, held July 18-20 at the University of Delaware, in Newark.

"Studying temperament—including one of its key components, response to novelty—has an important impact on equine welfare and the human-horse relationship," Berger said.

She explained that horses commonly display a startle response when faced with novel objects. "Horses that detect a novel object may startle and flee from it, then avoid it, ignore it, and approach it. The most reactive individuals—those most likely to startle—are those most likely to investigate (the object) if not forced." This contradictory behavior is what researchers call the "novelty paradox," which Berger took into account while performing her research.

In the study Berger and her team evaluated the behavior of 46 adult Thoroughbreds and Quarter Horses (25 mares and 21 geldings, primarily Thoroughbreds and Quarter Horses ages 3-29) housed in their home outdoor pens when presented with three novel objects: a yoga ball, a plastic saucer, and a hollow cube made of PVC pipe.

First, a researcher unfamiliar to the horses entered each pen and scored each horse's response to being approached (its sociability rating) on a five-point scale. The horse scored a 5 if he approached the researcher within two seconds, and he scored a 1 if he never approached or fled the researcher.

The researcher then calmly placed the three objects, one at a time, into a horse's pen and exited. Berger recorded each horse's behavior responses for 10 minutes and noted the number and duration of investigations of each object, the number of startle responses, and the horse's latency (amount of time it took) to investigate an object.

Berger observed that:

  • Startle was rare;
  • 30 horses never startled, 12 horses startled once, two startled twice, one three times, and one four times.
  • The order in which the objects were presented had no effect on startle response.
  • The saucer was associated with significantly more startles than the ball.
  • Horses that startled had much quicker latencies (36 seconds elapsed, on average, before they investigated the object) than horses that never startled (72.81 seconds).
  • Age correlated with latency: the older the horse, the longer he took to approach the object, Berger said.
  • Sociability rating (how quickly the horse approached a person) inversely correlated with latency to investigate. - There were no gender or breed differences.

"In our study, startling was rare," Berger summarized. "However, the horses that startled the most tended to investigate the object most quickly, supporting the general idea of the novelty paradox."

So what can owners and trainers take away from this study? Berger's colleague Alexali Brubaker, PhD, of the University of California, Davis, department of psychology, explained that "even spooky horses can often be naturally inclined to explore new things voluntarily if the new things aren't forced upon them." In riding or training situations she suggested waiting patiently until a horse's natural curiosity draws it to investigate something.

Disclaimer: Seek the advice of a qualified veterinarian before proceeding with any diagnosis, treatment, or therapy.

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