Horse Preferences for Insolation, Shade or Mist Curtain in the Paddock under Heat Conditions: Cardiac and Behavioural Response Analysis

SIMPLE SUMMARY: Most housing guidelines for horses recommend providing access to shade in paddocks and pastures on hot days. Some paddocks are equipped with mist curtains to enable horse cooling. However, earlier studies on horse behaviours have shown that the provision of shade is not an absolute care requirement. The use of mist curtains by horses has not been scientifically studied until now. The objective of the current study was to determine which area in a paddock (insolated, shaded, or water sprayed) is most often chosen by horses during a short, 45 min stay in a hot environment (29–32 °C, 42.0% humidity) and whether horses’ behaviour and emotional arousal (expressed by cardiac variables) are related to exposure to factors prevailing in these places. The study found that the horses’ preferences regarding the conditions in the paddock were not evident, although particular horses differed in this respect. The horses did not show symptoms of overheating while staying in the sun. They were more relaxed in insolated and water sprayed areas than in the shade. The free choice of different areas provided in paddocks seems to enable horses to maintain body temperature and emotional arousal at similar levels. ABSTRACT: The horse’s welfare and, consequently, the emotional arousal may be connected with stressful environmental conditions. This study aimed to determine whether horses show behavioural or physiological symptoms of thermal discomfort and if their behaviour and cardiac parameters are related to freely chosen insolated (IS), shaded (SH), or water sprayed (with a mist curtain (MC)) areas in a paddock under heat conditions (29–32 °C, 42.0 ± 1.5% humidity). Twelve adult horses freely moving in the paddock were studied during a 45 min solitary turnout. Six cardiac variables, locomotor, and non-locomotor activities as well as rectal temperature before and after the test were monitored with regard to the area of staying. Horses did not show clear preferences regarding the time spent in IS, SH, and MC, although preferences of particular horses differed considerably. When staying under IS and MC conditions, the horses showed a higher level of relaxation compared to SH. Horses did not exhibit symptoms of thermal discomfort while staying in the sun. Free choice between the three areas differing in environmental conditions could be a crucial factor in maintaining body temperature as well as emotional arousal at similar levels. Thus, the provision of a shade and mist curtain in paddocks seems to be reasonable.