Evaluation of dynamic structural disorders in the upper airways and applied rein tension in healthy dressage horses during riding in different gaits and head-neck positions

Abstract Flexion of the horse’s head and neck during dressage riding reduce the pharyngeal lumen with the risk of increased upper airway resistance and upper airway obstructions. According to the Federation Equestre Internationale, hyperflexion is achieved through force, whereas the position low-deep-round is non-forced. Objectives of this study were to evaluate: 1) applied rein tension, and 2) dynamic structural disorders in the upper airways in dressage horses in different gaits and different head-neck positions (HNP). Overground endoscopy (OGE) and rein tension were evaluated in 13 clinically healthy and high-performance Warmblood dressage horses while being ridden in a standardised programme comprised of four different gaits (halt, walk, trot, canter) and in four HNPs (unrestrained, competition frame, hyperflexion and low-deep-round). All included horses were able to achieve the desired HNPs. The HNP low-deep-round showed significantly lower rein tension than competition frame (p The HNP hyperflexion was neither associated with greater rein tension, nor severe dynamic structural disorders than the HNP competition frame. This study confirms that low-deep-round is a non-forced position, in contrast to hyperflexion. Further studies are needed in order to evaluate whether dynamic structural disorders are a result of flexion or if the degree of flexion has an impact.