Sun or shade: Do horses have a preference on a hot day?

You can provide a horse with shade in a paddock on a hot day, but they won't necessarily seek it out in preference to the sun.
You can provide a horse with shade in a paddock on a hot day, but they won’t necessarily seek it out in preference to the sun.

The old saying goes that you can lead a horse to water but you can’t make it drink.

It transpires you can also provide a horse with shade in a paddock on a hot day, and even a mist curtain to assist in cooling, but they won’t necessarily seek it out in preference to the sun.

Researchers in Poland have described a study in which they explored the paddock preferences of horses for sun, shade, or a mist curtain.

Iwona Janczarek and her colleagues at the University of Life Sciences in Lublin noted that most housing guidelines for horses recommend providing access to shade in paddocks and pastures on hot days.

Horses, they said, possess a high metabolic capacity, but have a relatively small surface area for dissipation of heat. Thus, they suffer a disadvantage compared to many other species.

“It is commonly believed that shady places are indispensable for horses during hot weather, hence providing access to shade is recommended by most guidelines.”

Mist curtains are sometimes installed in the paddock to enable immediate cooling.

However, horse owners often claim that their animals rarely seek shade on hot days. Furthermore, the findings of a 1990 study indicated that horses do not extensively profit from shelters that are built to minimize chilling in cold weather or discomfort in hot weather.

Yet behavioural and physiological studies performed on horses in a hot, sunny environment showed that horses prefer shade when it is available.

“However, the outcomes did not lead to the conclusion that the provision of shade is an absolute minimum care requirement.”

Janczarek and her fellow researchers set out in their study to determine which area in a paddock — the sunny, shaded, or water sprayed portion — is most often chosen by horses during a short 45-minute stay on a hot day, with temperatures of 29 to 32 degrees Celsius and humidity of 42%.

They also monitored heart variables to gain insights into whether the horses’ behaviour and emotional arousal were affected by the different areas.

Twelve adult Warmblood horses, comprising six mares and six geldings, were involved in the study, all of whom were normally kept in stables. The sand-covered paddock used in the study measured 40m by 45m. About 45% of the paddock was shaded by trees, and the mist curtain was installed in a corner.

The authors, writing in the journal Animals, found that the horses did not show a clear preference regarding the time spent in any particular area, although the preferences of individual horses differed considerably.

When staying in the sun or under the mist curtain, the horses showed higher levels of relaxation compared to the shaded areas. Perhaps the horses which displayed a higher ability of thermoregulation in the sun remained there, while those who felt discomfort in the sun more often used the shade.

“This could be a reason for the higher activity of the sympathetic nervous system (shown by heart rate variables) in horses staying in the shade.”

Essentially, however, the horses showed similar levels of emotional arousal in all three areas.

The horses did not show any signs of thermal discomfort while in the sun, with rectal temperatures taken before and after time in the paddock.

“The current study shows that the horses’ preferences regarding the conditions in the paddock during heat are not evident.

“This,” they said, “may result from high resistance to the heat of non-exercised but freely moving horses, particularly during a short turnout.”

Further research should explore whether preferences might change during a longer turnout.

They stressed that the free choice of the areas, each offering different environmental conditions, may be a crucial factor in maintaining body temperature as well as emotional arousal.

“Thus, the provision of a shade and mist curtain in paddocks seems to be reasonable.”

The study team comprised Janczarek, Anna Stachurska, Izabela Wilk, Anna Wiśniewska, Monika Różańska-Boczula, Beata Kaczmarek, and Witold Kędzierski, all with the University of Life Sciences in Lublin; and Jarosław Łuszczyński, with University of Agriculture in Cracow.

Janczarek, I.; Stachurska, A.; Wilk, I.; Wiśniewska, A.; Różańska-Boczula, M.; Kaczmarek, B.; Łuszczyński, J.; Kędzierski, W. Horse Preferences for Insolation, Shade or Mist Curtain in the Paddock under Heat Conditions: Cardiac and Behavioural Response Analysis. Animals 2021, 11, 933.

The study, published under a Creative Commons License, can be read here

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