We’re getting the message now: Horses don’t like being separated from other horses. And as the research pours in, we’re finding more and more support for that idea. Case in point: British researchers have confirmed that horses tend to show more physiological signs of stress when they’re housed in individual stalls, whether they act like it or not.
“The physiological changes we saw in our study horses cannot be masked in the same way that a horse can mask behavior (a survival mechanism in a prey species),” said Kelly Yarnell, PhD, researcher at Nottingham Trent University, in Nottingham, U.K. “And unfortunately, in the most isolated housing (individual box stalls), adrenal activity was very high (which can result in high levels of cortisol, the “stress hormone,” being released). If very high levels of cortisol are present chronically or on a highly repetitive basis, then this can be detrimental for our horses’ health.”
In their study, Yarnell and her colleagues tested fecal cortisol levels, eye temperature, and behavior during handling in 16 university lesson horses housed in four environments:
- Individual box stalls with no physical contact;
- Individual box stalls with limited physical contact;
- Group stalls housing two horses together; and
- Group pens housing several horses together.
All horses were on a break from lessons during the summer and were kept in a pasture before the experiment began. They had, however, all been introduced and were accustomed to each kind of housing situation before the study began, so nothing was new. When the researchers brought the horses into the stables for the experiment (each horse got to test each situation for five days), they were careful to bring in all the horses at about the same time so they didn’t experience stress from just getting left out of the larger herd, Yarnell said.
By far, the horses showed the highest levels of fecal cortisol when housed in individual box stalls with no physical contact with other horses, she said. Although they could see each other over their respective barn doors if they were looking over at the same time and could hear each other, they were otherwise completely isolated, as is common in many stables.
By contrast, horses in the group housing situation had the lowest eye temperatures (indicating the lowest stress levels) and were easier to handle than the horses in the other housing situations, Yarnell added.
Individual stabling systems have developed partially out of convenience and partially out of a mistaken understanding of what’s comfortable for a horse, she said. Through anthropomorphism (attributing human feelings and ideas to horses), people have often thought that their horses would be “happier” in a barn with their own personal space. And while that kind of stabling has some real benefits—such as protection from predators or conflict-related injuries and shelter from bad weather—it can also lead to unhealthy stress levels.
“If you consider this logically, taking the horses’ evolution into consideration, then you must think about how these animals have lived for millions of years, on wide open areas with room to roam in social groups, trickle feeding as they moved and as their physiology is designed to do,” Yarnell said. “Stabling is the opposite: isolation, reduced space, and limited food. These disadvantages can all contribute to elevated anxiety and reduced welfare for a social, free-ranging prey species.”
While many owners would be quick to agree with this concept, others have argued that, actually, their horses prefer their individual stalls to being outdoors with other horses, Yarnell told The Horse. “Since my scientific paper was published, I’ve had many owners comment that their horse waits at the gate to be brought into his stable,” she said. “I think it’s more likely the horse is waiting at the gate for his dinner! However, I accept that there may be exceptions.”
But, on the whole, even if current individual-stall stabling systems aren’t ideal, it’s not a reason to wrack ourselves with guilt, Yarnell added. “I wouldn’t say that it’s cruel,” she said. “I think there is a place for stabling our domestic and companion horses but perhaps not for extended periods due to the negative aspects.
“My recommendations would be that horse owners ensure that their horses have time to socialize or have contact with other horses and to move and feed wherever possible,” Yarnell said. “I’m not suggesting we all set our horses free, but there is a happy medium. Offering the opportunity for social interaction with conspecifics and the freedom to express natural behavior can improve equine welfare. And if there’s a housing type available that facilitates this, then I would encourage it to be utilized.”
The study, “Domesticated horses differ in their behavioural and physiological responses to isolated and group housing,” was published in Physiology and Behavior.