Influences of Double Versus Snaffle Bridles on Equine Behaviour at Dressage Competitions and Factors That Interact with Their Effect

Despite welfare concerns, conflict behaviours (indicative of momentary states of acute stress) are common in horses during dressage competitions. Identifying factors that affect conflict behaviours during competition therefore has the potential to improve equine welfare. The aim of this exploratory study was to assess the effect of bridle type (double versus snaffle) in relation to other potential affecting factors (e.g., average head angle, competition level and type, tack variation) on conflict behaviours during dressage competition. An ethogram was created to analyse the conflict behaviour of horses (<i>n</i> = 135) at dressage competitions. Behaviours were reduced into nine components using principal component analysis. The effects of bridle type and its interaction with other additional factors (competition level, competition type, average head angle) on component scores were analysed using multilevel Bayesian regression models. The results demonstrated a multifaceted interaction between bridle type, inferred rider skill level, and ridden head angle. The results also demonstrated that during dressage tests, 100% of horses performed the conflict behaviours of mouth opening and 86.7% of horses performed tail swishing. The ethological and welfare implications of these findings are discussed.