Such findings suggest that even during brief turnout, horses should have choices, said Anna Stachurska, PhD, in the Department of Horse Breeding and Use at the University of Life Sciences in Lublin, Poland.

“The horses in our study had widely different preferences,” Stachurska said.

On average, the horses stayed in the sun as much as in the shade, but individually they showed clear inclinations for one or the other. And as for mist curtains—which spray cool water gently from an overhead bar—only a few of the horses used them, but they did so frequently.

“It’s like humans,” Stachurska explained. “When the air is terribly hot, some people do not like to get into a lake, although it gives such relief. Or if we consider dogs, one dog might jump into water but another one hates it.”

To understand horses’ preferences during short paddock turnout—which is common practice in many stables—Stachurska and her fellow researchers observed 12 riding school horses (six geldings and six mares) housed in box stalls. They placed the horses individually into a sand paddock equipped with shaded areas and a mist curtain. The horses stayed in the paddocks for 45 minutes when outdoor temperatures ranged from 88 to 93 degrees Fahrenheit.

The team found that as a whole—and much to the researchers’ surprise—the horses didn’t show distinct preferences for staying in the sun, shade, or mist, Stachurska said. But individually, some horses spent significantly longer periods in one area than the others.

In particular, the horses had very divided preferences regarding the mist curtains, she said. Five of the horses used them occasionally, and three of them stayed under the mist curtain for more than 33 minutes of their 45-minute turnout. Meanwhile, four horses never used them.

None of the horses had increased body temperature during this brief turnout, regardless of their preferences for sun, shade, or water, said Stachurska. Behavioral measures and heart rate monitoring suggested they were relaxed, even in the hot sun.

However, she said it’s important to keep in mind the results came from a brief, 45-minute test. For longer periods, intervening on the horses’ behalf might be necessary—especially if horses stay in the sun for long periods, because some horses might like the heat even if it’s not good for them.

“Since humans domesticated horses, they should take full responsibility and provide safe conditions for horses, like taking them out of hot paddocks and into a cooler area when there’s too much heat,” Stachurska said.

Paddocks should always offer shade, even for short-term turnout and even if the horse doesn’t use it much, said Stachurska. Mist curtains could also be useful, “but they’re not indispensable,” she said.

Handlers should avoid putting their horses outside at the hottest time of day—especially if they don’t use shade—and shower them with cool water if needed, she concluded.