The asymmetric movement induced when lungeing a horse may not necessarily be the same in both directions, researchers have found.
The team of researchers based their findings on measurements taken from horses on the lunge which were fitted with sensors that measured the animals’ vertical head and pelvic motion pattern.
The scientists, from Sweden, Britain and the United States, said lungeing was commonly used as part of standard lameness examinations in horses, which meant there was a need for knowledge of how motion in sound horses was affected by the technique.
Marie Rhodin and her colleagues began with a pool of 201 riding horses – 100 in Sweden and 101 in the United States. All were considered sound by their owners.
They were each evaluated in trot on a straight line and during lungeing to the left and right, using two uni-axial accelerometers and a gyroscope attached to their bodies.
From this pool, 94 horses with symmetric vertical head and pelvic movement during the straight-line trot were retained in the study for more detailed analysis. The team opted for this criteria for inclusion in the absence of a gold standard to define soundness on the lunge.
“Vertical head and pelvic movements during lungeing were more asymmetric than during trot on a straight line,” they reported in the Equine Veterinary Journal.
“Common asymmetric patterns seen in the head were more upward movement during push off of the outside forelimb and less downward movement during impact of the inside limb,” they reported.
Common asymmetric patterns seen in the pelvis were less upward movement during push-off of the outside hindlimb and less downward movement of the pelvis during impact of the inside hindlimb, they reported.
“Asymmetric patterns in one lunge direction were frequently not the same as in the opposite direction.”
The researchers said lungeing induced systematic asymmetries in vertical head and pelvic motion in horses resulting from moving in a circle that may not be the same in both directions.
“These asymmetries may mask or mimic forelimb or hindlimb lameness.”
The study team said their observations begged the question as to whether the horses who did not get beyond the pool of 201 were really lame or simply asymmetric. “And if they are lame, does this constitute a potential welfare issue for competition horses?”
Further studies were needed, they said.
M. Rhodin, L. Roepstorff, A. French, K. Keegan, T. Pfau and and A. Egenvall.
Head and pelvic movement asymmetry during lungeing in horses with symmetrical movement on the straight.
Equine Vet J. 2015 Mar 25. doi: 10.1111/evj.12446
The abstract can be read here.