Scientists Study Facial Expressions of Pain in Ridden Horses
Scientists have already described how to spot signs of pain, such as from colic or castration, in horses by their facial expressions. But what about recognizing pain signals in ridden horses?

British researchers say identifying the facial expressions of pain in mounted horses requires a whole new set of observation skills. And their research group is working to produce just that.

“I have used these observations of behavior for years, and they really help me determine when musculoskeletal pain is the underlying cause of poor performance,” said Sue Dyson, MA, Vet MB, PhD, DEO, FRCVS, Head of Clinical Orthopedics at the Animal Health Trust Centre for Equine Studies, in Newmarket, United Kingdom.

In this first of a four-part study, Dyson and colleagues developed an ethogram—a behavior observation “checklist”—for recognizing facial expressions in ridden horses. They based their ethogram on published descriptions of facial behaviors and studying photographs of 150 lame and sound ridden horses, she said.

Then, they created a training manual for recognizing these behaviors and taught 13 horse people—veterinarians, technicians, equine studies graduates, a veterinary nurse, a riding instructor, and horse owners—how to do just that. These individuals were then tested on their training, the results of which led the scientists to adjust the ethogram and training and test the same group of observers again. Testing involved a visual examination of 30 photographs of side views of ridden horses’ heads. Some of the horses were lame while others were sound, Dyson said.

The scientists found that the second round of testing resulted in good consistency—meaning the observers tended to spot the same behaviors in the photos. For some behaviors, such as having a wrinkle between the nostrils, the observers noted that they couldn’t see whether the horse made the behavior—but this could be resolved with frontal view photos or seeing the horse in real life, Dyson explained.

While it’s still too early in the research process to describe the various facial expressions that are specifically related to pain in ridden horses (which make up Part 2 of the research series), Dyson said that some of the “key elements” they found were, “not surprisingly, ears back, glazed expression, and mouth open.”

Ridden horses express pain through facial behaviors differently from horses at rest, she said. Much of this is because of the constraints put on them by tack and athletic requirements. However, that doesn’t mean they don’t show visible signs of pain in their facial expressions. And no, she adds, it’s not just a question of the horses responding to the riders’ cues.

“Having spent many, many hours watching lame and sound horses in a variety of environments, I am absolutely sure that we will be able to distinguish facial expressions that reflect pain (with some overlap with conflict behavior) and those that reflect attention to external cues,” Dyson said. “I use it on a daily basis.

“I am confident that the data will give us statistically robust results,” she continued. “Obviously there are potential confounding factors such as a crank flash noseband, but nonetheless using these observations is very valuable.”

The study, “Development of an ethogram to describe facial expressions in ridden horses (FEReq),” was published in the Journal of Veterinary Behavior.