Scientists Study Body Lean in Sound Horses - Equine Health and Welfare

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Scientists Study Body Lean in Sound Horses

HCBC Staff
Created: December 14, 2016

study results suggest some horses compensate for lameness by changing the angle of leaning in one direction of a circle.

They found that younger horses (age 6 and under) leaned more than the predicted angle, whereas horses aged 7 and older leaned less.

How a horse leans into a circle can depend on his age and experience—we’ve all seen the young, green horse look like he’s about to tip over as he makes the turn while the more experienced schoolmaster balances his body beautifully. But researchers have found another factor that could determine how much a horse leans on a circle: his soundness. Recent study results suggest some horses compensate for lameness by changing the angle of leaning in one direction of a circle.
This discovery complements other recent studies highlighting the ways lame horses sometimes show very subtle signs of their pain—far less obvious than the classic head-bobbing limp, said Sue Dyson, MA, Vet MB, PhD, DEO, FRCVS, head of clinical orthopaedics at the Animal Health Trust (AHT) Centre for Equine Studies, in Newmarket, United Kingdom.
“I spend hours watching horses under all circumstances, and for a very long time I’ve been aware that there are many different ways in which horses adapt to pain and lameness,” she said. “I was pretty sure that non-lame horses moved symmetrically to left and right, but that some lame horses do not.”
In her latest study on equine movement, Dyson and Line Greve, DVM, MRCVS, a PhD student at the AHT, investigated 13 sound dressage horses working under saddle or on the longe. The horses’ regular professional riders worked them in straight lines and in 35-foot (12-meter) circles at different speeds of trot and canter.
The researchers equipped each horse with inertial measurement units (IMUs) and a global positioning system (GPS) to register velocities and angles, Dyson said. They calculated a “predicted lean” angle that would seem consistent with the laws of physics for horses to stay upright (and not fall) while moving in a circle.
Well-schooled horses showed less body lean than their less experienced counterparts.
Photo: Mallory Haigh/The Horse
They found that younger horses (age 6 and under) leaned more than the predicted angle, whereas horses aged 7 and older leaned less, Dyson said. Also, horses with higher dressage performance scores leaned less than horses with lower performance scores.
“These results confirmed what was already clear to me from subjective assessment: that young horses have greater body lean than older horses with better musculoskeletal strength and coordination and that well-schooled horses have less body lean than those that are less well-schooled,” she said.
While the current study provides a good basis of comparison—setting a definition of “normal” angles in sound horses—Dyson said her research has continued, this time focusing on lame horses. In a soon-to-be-released study, they found that horses with an asymmetrical lean (different lean angles in each direction of the circle) became more symmetrical after receiving an analgesic in the suspected lame limb. More information on that study will be revealed in a future article at
In the meantime, however, horse owners and practitioners should keep an eye on body lean in their horses, Dyson said. If people know their horses well, high-tech equipment isn’t necessarily required for an initial evaluation. “I think it is a matter of training your eyes to look and see,” she said. “I do it every day—without IMUs!”
The study, “Body lean angle in sound dressage horses in-hand, on the lunge and ridden,” was published in the Veterinary Journal.
About the Author

Christa Lesté-Lasserre, MA
Christa Lesté-Lasserre is a freelance writer based in France. A native of Dallas, Texas, Lesté-Lasserre grew up riding Quarter Horses, Appaloosas, and Shetland Ponies. She holds a master’s degree in English, specializing in creative writing, from the University of Mississippi in Oxford and earned a bachelor’s in journalism and creative writing with a minor in sciences from Baylor University in Waco, Texas. She currently keeps her two Trakehners at home near Paris. Follow Lesté-Lasserre on Twitter @christalestelas.

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