Effects of lighting conditions on the welfare of horses being loaded for transportation

Horses are transported for a variety of purposes. Loading the horse onto a trailer or horsebox can be a source of stress and injury for both the horse and handler. This study investigated whether lighting conditions either inside or outside the trailer influence the welfare of horses during loading. Eight horses were initially trained to enter a trailer for a food reward, and were then loaded into an enclosed trailer either from a dark or lit arena and into a dark or lit trailer, in a replicated Latin Square design. Heart rate increased from the start to the end of each test in all treatments, suggesting that the horses experienced some fear of the loading process. However, there was no effect of lighting treatment on the increase in heart rate or the maximum or mean heart rates. Neither was there any effect of treatment on the speed of loading or number of refusals, which when examined with the heart rate data, suggests that there was no effect of lighting treatment on the horses’ fear of loading. However, horses loading from a lit arena were more likely to turn away from the trailer or lower their head than horses loading from a dark arena. In addition, those loading from a lit arena to a dark trailer sniffed the ground more, showing increased exploration of their environment. It is concluded that the amount of fear shown by horses was not affected by lighting conditions inside or outside the trailer, but there was some evidence of negative emotions when they loaded from a lit arena, particularly when they were entering a dark trailer.