By measuring gait symmetry—the evenness of a horse’s left steps to its right during various gaits—scientists are able to gather significant information about loading, or the weight horses can carry on their backs. Gaits that get sufficiently out of sync, they say, are a strong indicator of how much is too much.
“We showed a widely applicable and welfare-friendly method to evaluate loading capacity of horses by gait analysis using an accelerometer,” said Akihiro Matsuura, PhD, lecturer in the department of animal science at the Kitasato University School of Veterinary Medicine in Aomori. Scientific analysis of the accelerometer readings revealed certain “peaks” that could be defined as the symmetry of the gait, he added.
Matsuura colleagues from Kitasato University and the Towada Riding Club, studied Japanese horses at the walk and trot. The six study mares—relatively small Hokkaido native horses—averaged 14.1 hands in height and 340 kilograms (750 pounds) in weight. They were ridden by the same 66-kilogram (145-pound) rider in all tests, but researchers loaded the horses progressively with more and more weights, with a maximum of 130 kilograms (287 pounds) total weight. Researchers evaluated the horses with an accelerometer as they moved in a straight line at predetermined, fixed speeds.
Their results showed that the horses appeared to manage loading relatively well up to 95 kilograms (209 pounds). At 100 kilograms (220 pounds), the horses showed a significant lack of symmetry as represented by uneven peaks in the acceleration readings. In order to leave a safety margin for tack, equipment, and clothing, Matsuura said he and his colleagues recommend keeping weight load under 100 kilograms for these horses.
“In light of the safety of the rider and horse, we speculated that 100 kilograms, which is 29% of body weight, is an appropriate weight for the maximum permissive load weight,” he said.
Horses used in therapeutic riding classes are at particular risk of overloading, Matsuura said, noting this was the original focus of his study.
“The Riding for the Disabled Association (RDA) indicates that disabled riders are often unbalanced riders, and this makes them seem heavier to the horse,” he said, noting that these riders are likely more unbalanced because they have restrictions in controlling their bodies. “They also tend to have weight issues because of a relatively sedentary lifestyle.”
So will all horse breeds follow the same trend in regards to how much weight they can comfortably carry? Probably not, Matsuura said. Certain types of horses can handle more (or less) loading than others, he noted, so ideally different breeds should be evaluated for maximum weight loading recommendations.
The study, “Method for estimating maximum permissible load weight for Japanese native horses using accelerometer-based gait analysis,” was published in January in the Animal Science Journal.