A new study by Italian researchers reveals that horses enter a positive emotional state—essentially, being more relaxed—when they see a familiar human who’s developed a good relationship with them. And that positive emotional state increases when the person gently brushes the horse, said Chiara Scopa, PhD, research fellow at the National Reference Centre for Animal Assisted Interventions, Experimental Zooprophylactic Institute of Venice in Padua, Italy.

“By defining a ‘familiar human’ as someone whom animals have had multiple occasions to interact with and establish a relationship of a positive emotional valance, we can positively affirm that horses are able to develop a bond with them,” Scopa said.

Testing Both Heart Rate and HRV to ‘Read’ Equine Emotions

Scopa and her fellow researchers observed 23 mixed-breed horses in leisure riding stables as familiar and unfamiliar humans approached them in their stalls. Each familiar human was chosen by the stable staff as having developed a positive relationship with the horse being tested. The unfamiliar people had experience with horses but had never “met” the horses in the study.

The scientists analyzed the heart rate and heart rate variability (HRV) of the horses as they stood alone in a stall, as a human (familiar or unfamiliar) came into the stall quietly and stood still, and as that human took a soft brush and groomed the horse on each side for a total of five minutes. The horses wore wearable equipment as developed and tested by researchers at Feel-Ing s.r.l.’s, a spinoff of the Department of Information Engineering, at the University of Pisa, Italy, which also collaborated in this study.

They found that the horses had lower heart rates when being groomed, regardless of who groomed them. However, their HRV rates differed significantly when they were interacting with familiar versus nonfamiliar humans. “These complex additional analyses on the sympathovagal correlate (which is measured by HRV) revealed a modulation of the cardiovascular neural regulation related to the level of the handler familiarity,” said co-author Laura Contalbrigo, DVM, PhD, also of the Italian National Reference Centre for Animal Assisted Interventions.

“In other words, by measuring horses’ sympathovagal balance, we were able to verify that horses show different reactions whether they are in the presence of familiar or unfamiliar humans,” Contalbrigo said. “By correctly interpreting physiological activity, it is actually possible to ‘read’ the animal’s emotional state.”

The Horse-Human Relationship Is Complex

Those readings suggest the horse-human relationship is highly complex and depends on the history of the relationship as well as the kinds of current interactions. For example, horses had HRVs that indicated a much more positive emotional state than just resting when the familiar humans brushed them on either side. But with the unfamiliar humans, the horses seemed to have somewhat more positive emotions during brushing only when that person brushed their left side.

“We indeed cannot simply focus on the contact with people alone, but on the different levels in which that contact can occur, from not being able to see each other, to sharing the same area, to having the opportunity of physical contact,” Contalbrigo said.

“Would you say that your level of familiarity with a specific person is only caused by your ability to recognize him or her? Or do you think that your level of familiarity has the potential to affect your emotional states?” she continued. “We believe that the idea that horses’ behaviors and emotional states are just tuned to simple cause-effect reactions should be broadened and explored further. As we can see from this study, in fact, it is their emotional world that drives their reactions and that calibrates the different ways in which they interact with people.”

A Relationship Built on Positive Experiences, Day After Day

This team’s study strengthens an idea that many horse people have believed for years: that the horse-human relationship starts from a series of day-by-day interactions, and that to be a positive relationship, the interactions themselves need to be positive, said co-author Paolo Baragli, DVM, PhD, researcher and professor specializing in the horse-human connection at the University of Pisa Department of Veterinary Sciences.

“In the same way it happens for dogs and people, horses develop a relationship with subjects who are present in their life on a daily basis,” Baragli said. “The relationship is based on subjective experience and specific memory of each encounter, and regardless of whether it was bad or good, we nevertheless leave behind a sort of ‘print.’ Our aim should always be one of growing a positive bond, keeping in mind that horses learn about us from our actions, which are constantly labeled.”

That’s particularly true when it comes to physical touch, he added. “It is difficult to think of a human-horse activity that does not include some form of contact, and the bonding process, in fact, starts with physical contact,” said Baragli. “Information collected through the body is mainly used to anticipate the movements of the partner (both horse and human); body contact constitutes an emotional channel of connection between the individuals interacting. The occurrence of repeated encounters in the long term is useful for both motor coordination and socioemotional engagement between the bonding subjects.”

It’s because of this that the scientists also framed the study, which was funded by the Italian Ministry of Health, as a tool for improving Animal Assisted Interventions (AAI) along with animal welfare and the study of emotional intelligence in horses, Scopa said.