Horses show limited owner bias in reunion and odor tests: a pilot study

Compared to other companion animals, our understanding of the human-horse relationship is limited, particularly from the horse's perspective. This pilot study examined whether horses (N = 30) show a bias towards their owner in a reunion in the presence of both the owner and a stranger. Afterwards, the horses were also presented with the odor of the owner and a stranger. Both tests were video recorded for behavioral analyzation. No significant owner-directed bias was observed at the group level in either the reunion test or the odor test. Nonetheless, in the reunion test, owner bias in physical contact - though limited in number - was positively associated with the length of the horse-owner relationships. There were no effects of sex (mares and geldings) or types of horses (Icelandic horses, pony-sized breeds, and larger horse breeds), or age. In the odor test, older horses revealed a stronger owner bias than younger horses, but no significant effects were found for sex, horse type, or relationship length. Hence, we did not find evidence of a conclusive owner bias in our tests. Therefore, we speculate that horses may form a more generalized relationship with humans, based on their previous individual experiences with humans.