Horses who live outside during hot weather are vulnerable to the elements. Whether it is raining, windy or sunny, it is vital to provide adequate shelter to provide protection from conditions that could result in either discomfort or illness. During summer or in hot climates, it is common sense for horse owners to provide their horses with protection from the harsh rays on the sun. Excessive exposure to sun, as we saw in previous articles, can lead to sunburn, increase susceptibility to melanomas, dehydration or, for horses with anhidrosis, overheating.
There is a dearth of research on the potential benefits of shade for horses. Researchers at the University of California, Davis, conducted a study into whether horses showed a preference for shaded or unshaded areas in hot, sunny, summer weather. Their study hypothesis was based on a previous study which showed that horses who had no access to shade suffered from greater rectal temperatures and increased respiration rate. Horses who did not have shade produced more sweat than horses that were completely shaded. Yet, this apparent benefit is dependent on horses choosing to stand under the shade provided.
The trial carried out at University of California involved twelve healthy, adult horses. They were used in three different trials, whereby they were split into groups of four horses each. Each trial involved two days acclimation and five to seven days of observation. The horses were housed individually in dry lots and the southern half of each pen was covered by an open‐sided shade structure. The amount of shade across the pen was varied throughout the day, depending on the position of the sun and the covering, with an average of 51% of the pen shaded. To monitor the horses, they had their rectal temperature, respiration rate, skin temperature and sweat score measured three times a day - once in the morning, afternoon and in the evening. The behavior of the horses was also observed and recorded. These behaviors that were recorded included each horse’s location relative to shade, and time spent walking, foraging and standing. Horses were considered to be “in shade,” if at least two hooves were shaded by the shade structure.
Results demonstrated that, during the study period, the more horses spent more time in the shade than in the exposed areas. When looking at how active the horses were, they spent more time walking and displayed more foraging behavior when in the shaded areas. This was not limited to daylight hours, it was also found that the horses spent more time at night beneath the shade structure than in the uncovered area, again demonstrating more activity in that location. Therefore it can be clearly seen from the results that individually housed horses will choose to use and prefer to spend their time in shade when it is available in hot, sunny environments. It is also possible to increase activity levels by providing shade which in turn may suggest the horses are happier when provided with coverings providing shade. When spending longer periods in the direct heat, the horses were adversely affected: their body temperature, sweat levels and respiratory rates all increased. While in the shaded areas, the horse’s vital signs remained constant or within normal parameters. The results support recommendations for providing horses with access to shade, whether owners are hastily assembling an impromptu equine shelter or developing best management practice guidelines for horses in comprehensive equine facilities.
*Image courtesy of Dollar Photo Club
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