International Survey Exploring Rider-Perceived Sidedness of the Horse.

Laterality or sidedness in the horse is commonly addressed as part of the horse's training. An international online survey regarding horse and rider sidedness and asymmetry was conducted, with 2304 useable responses. Confidence intervals (95%) were used to evaluate if some response options were chosen more frequently. Discounting answers of 'not sure' or 'not applicable', the right fore hoof was more often perceived to be more upright (22%) than the left (15%), and the left shoulder was more prominent (24%) more often than the right (17%), whilst most respondents reported no difference. Both lunging and bending was perceived to be most difficult to the right (48% and 52%) than to the left (33% and 42%), and more horses fell in on the right circle (lunging 40%, riding 38%) than on the left (31% and 33%). Horses commonly tracked their hindquarters to the left in walk, trot and left canter. Correspondence analysis showed that responses indicating horse side bias and relative symmetry, respectively, were associated across several questions, suggesting consistent individual patterns. While the mechanisms underpinning sidedness remain unclear, this study provides insights into horse owners' perceptions of laterality and related matters.