Study: Horses are happier housed together

May 06, 2016

Eyes will be locked on televisions around the world this weekend as many eagerly anticipate the running of the 142nd Kentucky Derby. While for two solid minutes these racehorses are all business, it’s easy to spot them mingling with each other before and after the race.

That is why it comes as no surprise that research is showing horses don’t actually like being separated from other horses and show more physiological signs of stress when they’re housed in individual stalls, whether they act like it or not.

That was the finding at least of a recent British study in which scientists tested fecal cortisol levels, eye temperature, and behavior during handling in 16 university lesson horses housed in four different environments.

“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),” Kelly Yarnell, PhD, researcher at Nottingham Trent University, said in an article. “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.”

By far, the horses showed the highest levels of fecal cortisol when housed in individual box stalls with no physical contact with other horses, the article explains. Although they could see each other over their respective barn doors 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 said.

Individual stabling systems have developed partially out of convenience and partially out of a mistaken understanding of what’s comfortable for a horse, Yarnell explained. 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 in the article. “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 their horses prefer their individual stalls to being outdoors with other horses.

“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,” she said.

“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… Offering the opportunity for social interaction with conspecifics and the freedom to express natural behavior can improve equine welfare," Yarnell added.

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