Preference of domestic horses for shade in a hot, sunny environment.

The researchers aimed to analyse whether horses, when given a choice, preferred to stand in the shade in hot and sunny environments. They conducted a study with twelve adult horses, and found that the horses significantly preferred the shade, especially before and during the peak of solar radiation. In addition, horses moved and foraged more in shaded areas. This research informs the development of best practice guidelines for horse care in hot climates, reinforcing that access to shade should be a key aspect.

Objective and Methodology

• The study aimed to understand horse preferences for shaded or unshaded areas during hot and arid sunny summer weather. This was assessed in Davis, California. The objective arose from previous findings that horses without access to shade showed greater rectal temperature, respiration rate, and skin temperature, and sweated more than shaded horses.
• The methodology involved a preference test with 12 healthy adult horses, divided equally by gender. They were randomized into three sequential trials involving four horses each, with each trial comprising an acclimation period and an observation period. The horses were individually kept in dry lot pens, half of which was covered by shade.

Measurement and Observation

• Physiological measurements such as rectal temperature, respiration rate, skin temperature, and the amount of sweat were recorded three times a day.
• Behavioral observations were recorded at 5-minute intervals daily from the afternoon until evening, and at 10-minute intervals from evening until afternoon on alternating days. These observations included the horses’ location relative to shade, the time spent walking, foraging, and standing, as well as insect avoidance behavior.
• Weather factors such as ambient temperature were recorded every 5 minutes around the clock. The average daytime temperature was recorded as 29°C ± 5°C.

Results and Conclusion

• Horses were found in the shade in 7.1% more observations than would be expected by chance, with the greatest usage seen before and during peak solar radiation, and then again following peak black globe temperature.
• Horses showed more walking and foraging behavior in shaded areas. This indicated not only a preference for shade but also an associated increased activity in these shaded areas.
• The results thus strongly suggest that in hot, sunny environments, horses, when individually housed, prefer shade. These findings support the recommendation of providing access to shade as part of best practice guidelines for the care of domestic horses in such climates.