Impact of bit types on equine upper airways – implications for performance and welfare

Abstract

This study was conducted to clarify the behavioral dynamics of the equine larynx during exertion and rest under the influence of different bits, and to ascertain potential variations in the overall surface area of the larynx among bits within individual horses. Various researchers highlight the impact of bits on equine breathing and upper airway disorders. While some attribute respiratory discomfort solely to bit use, others suggest negative effects in combination with rein tension. Riding without a bit has been associated with improved animal welfare and reduced hyperreactive behaviors. The extreme sensitivity of the mouth to mechanical stimulation makes the bit a potential source of discomfort, leading to resistance, lesions, and injury. Poll flexion induced by rein tension and bit use can obstruct the airway, causing hy poxia and decreased performance. This investigation focused on three bits commonly used in international grand prix showjumping events in Europe during 2022: the loose ring bit, the three-ring bit, and the Pelham snaffle. Employing overground endoscopy, this research observed nine Warmblood horses engaging in walking, trotting, and cantering with different bits. An overground endoscope facilitated the examination of laryngeal behavior during motion. Statistical analyses revealed that the chosen bits did not significantly influence laryngeal behavior during different gaits. Similarly, there was no substantial variation in laryngeal surface area among bits within individual horses. However, a significant main effect of state (rest, trot, canter) highlighted the considerable influence of the horse's physiological state on laryngeal behavior.