By By Christa Lesté-Lasserre
From TheHorse.com
The kinematic variable of the relationship between the rider’s hand and the horse’s mouth is “of importance as it yields some information about the rider’s ability to follow the movement of the horse with the hand,” Eisersiö said. It’s very important, from a horse welfare standpoint, that riders continuously work on improving how they use the hand, she added.
Eisersiö and her fellow researchers studied seven dressage horses ridden by their regular riders at the sitting trot on a treadmill. The researchers focused on the horses’ head, ears, and mouth movements and compared these findings to the riders’ use of the reins and the phase of the trot. They also measured rein tension in three horses.
They found that when horses were “on the bit,” (with neck raised, poll at its highest point, and bridge of the nose slightly in front of the vertical, as seen in dressage competitions) they had considerably more mouth and lip movements during the suspension phase of the trot (when the horse has no feet on the ground) compared to the stance phase (when the feet are in contact with the ground). The horse could be reacting to unintentional rein pulling during this phase as the rider tries to maintain balance, Eisersiö said, but further research is needed.
Interestingly, the team said, rein tension on the left side tended to cause more mouth movements, while rein tension on the right tended to cause fewer movements. More research with more horse/rider combinations is necessary to explain and verify this phenomenon, Eisersiö said.
They also found that when the horse was ridden with loose reins and allowed a free, unrestrained position, the peak rein tension occurred in the mid-stance phase of the trot (the moment when the horse has two feet on the ground). Horses lower their heads naturally during this phase, Eisersiö said, which increases rein tension unless the rider follows the head movement with his or her hands.
Perhaps more importantly, the researchers noted, there are few “definites” when it comes to evaluating horses’ reactions to rider kinematics. There is great variability from rider to rider, Eisersiö said, which means each rider is going to be give different signals to each horse.
“Studying the horse’s behavior and its behavioral reactions to the rider’s interaction is important because it gives the rider feedback of the horse’s understanding of an exercise,” said Eisersiö. “It might also be a way to know if the horse is comfortable with the ridden work and, further, give us insights to what is going on in the horse’s mind.
“The bit in the horse’s mouth presses on sensitive oral tissues, and mouth behaviors are, in many cases, the way the horse handles the pressures in the mouth,” she continued. “The horse might be uncomfortable with the pressures applied on the tissues in the mouth and thus try to manipulate the bit in different ways to seek comfort.”
For improved horse welfare, Eisersiö said she encourages riders to manage their rein tension better. To do this, she said, riders should work on improving their seat. “The rider’s ability to follow the horse’s movements and separate the hand from the seat affects the kinematic actions of the hand,” she said. “To avoid acting on the horse’s mouth involuntarily, the rider should learn to follow the horse’s movements without effort and learn to separate the hand from the seat, never using the reins to get a steadier seat in the saddle.”
The study, “Movements of the horse’s mouth in relation to horse-rider kinematic variables,” was published in The Veterinary Journal.