Horses are generally relaxed about hanging out with their familiar human friends, fresh research has shown, but show more caution with unfamiliar handlers.
The results from the Italian study provide objective evidence of the capacity of horses to individually recognize a familiar person, indicating that familiarity with the handler is important in human-horse interactions.
Chiara Scopa and her fellow researchers said studies have shown that horses can discriminate between familiar and unfamiliar humans using both visual and vocal cues. They are also able to form long-lasting memories.
“This ability suggests that the level of familiarity can affect horses’ tendency to engage again with the same human, also allowing these animals to recognize their caretakers long after the last encounter,” the study team wrote in the journal Frontiers in Veterinary Science.
“A human-animal relationship can be developed through subsequent interactions, affected by the positive or negative emotional nature of the proceeding one.
“Horses implement a process of categorization to classify humans with whom they interact as positive, negative, or neutral stimuli by evaluating the kind of approach and the nature of the contact.
“In these terms, human-animal interactions are emotionally charged events, eliciting specific emotional states in both subjects involved.”
The study team said that although the human-horse relationship has been mainly investigated through behavioral analysis, physiological indicators are needed for a more objective assessment of the emotional responses.
The researchers expected that long-term positive relationships with humans may have a positive and immediate impact on the emotional arousal of horses, detectable via activity in the autonomic nervous system during contact.
Heart-rate variability is commonly used in this regard as a marker of emotion regulation in horses.
Scopa and her colleagues analyzed horses’ heartbeat dynamics during their interaction with either familiar or unfamiliar handlers, applying a standardized experimental protocol consisting of three different phases, shifting from the absence of interaction to physical contact.
Their work involved 23 healthy mixed-breed horses, all accustomed to interactions with two to six people for daily management. The horses were mostly involved in amateur-level riding activities, and were worked accordingly.
The researchers enrolled 22 people for the study, 12 of them participating as people known to be familiar to the horses and 10 as unfamiliar. For each familiar person, an unfamiliar person of the same sex was matched.
The protocol involved baseline heart measurements being taken before the individual, either familiar or unfamiliar, entered their stall and stood near the door for five minutes. The horse could see and smell them, but was otherwise free to move around as it chose. The person then picked up a brush and groomed the horse for two and a half minutes on each side.
The protocol was undertaken for each horse with the familiar and unfamiliar person.
The results showed a difference in the horses’ heartbeat dynamics depending on whether the person was familiar or not, and through the interacting sessions.
The findings showed that the emotional responses of the animals were affected not only by the handler’s familiarity but also the type of interaction he or she may have with it.
The findings indicated that horses appeared more relaxed while physically interacting with familiar handlers when compared with the same task performed by someone unfamiliar, which was especially noticeable during the right-side grooming.
“It is well-known that handling procedures on domestic horses are traditionally practiced on their left side,” the authors noted.
“Therefore, we hypothesized that the approach on the right side constituted an additional stimulus for tested horses, potentially perceived as an unusual handling position and thus contributing to the increase of their discomfort when performed by an unfamiliar handler.”
The study team noted that they did not consider individual horses’ temperament or reactivity in their study. “Rather, we focused on how long-term relationships with humans may affect horses’ emotional state in daily management activities, which generally involve some sort of contact.”
They continued: “The possibility to comprehend how an animal is experiencing contact with people is invaluable.
“Animal-assisted interventions may be one field that could benefit the most from this kind of approach.”
In conclusion, they said: “Our results suggest that a sequence of positive interactions with the same caretaker represents for horses the probable trigger for experiencing presumed positive emotions during the interaction itself.”
They said the novelty of their study lay in the possibility to obtain horses’ affective assessments, carried out through the objective analysis of their heart-rate variability.
“The opportunity to effectively measure the emotional state of an animal, in multiple conditions including during contacts with other individuals, paves the way for a broad variety of future studies that set the human perspective to the side so as to prioritize that of the animal.”
The study team comprised Scopa and Laura Contalbrigo, with the Italian National Reference Centre for Animal Assisted Interventions; Alberto Greco, Elisabetta Fratini, Enzo Pasquale Scilingo and Paolo Baragli, affiliated with the University of Pisa; and Antonio Lanatà, affiliated with the University of Florence.
Scopa C, Greco A, Contalbrigo L, Fratini E, Lanatà A, Scilingo EP and Baragli P (2020) Inside the Interaction: Contact With Familiar Humans Modulates Heart Rate Variability in Horses. Front. Vet. Sci. 7:582759. doi: 10.3389/fvets.2020.582759