b'move asymmetrically, or by having a rider on board. Her recent studies on rider influence show that the rising or posting trot causes considerable asymmetry in a horse. And that rider effect, combined with circling, can multiply or cancel out asymmetry, depending on which diagonal the rider is posting on and which direc-tion the horse is turning. COURTESY CAMBRIDGE EQUINE HOSPITAL, NEW ZEALANDOther factors, such as terrain, environ-ment, the horses mental status, and even day-to-day variations, could affect sym-metry readings, says van Weeren. Its not even accurate to say all lame horses are asymmetrical, he adds. A horse thats lame on both forelimbs or both hind limbs, for example, might move symmetrically despite significant pain. We have to keep in mind that lameness is a clinical term, butThe Lameness Locator is an inertial measurement unit (IMU) that comprises three sensors. Its asymmetry is not, van Weeren says.designed to help identify the lame limb, degree of asymmetry, and affected stage of the stride.Allowing for some level of asymmetry makes sense, because thats just part ofand magnetometers (to measurewhich Braganca says shows promising our physical individuality, regardless ofrotation, acceleration, and orientation,results in field tests. species, says Sue Dyson, MA, VetMB,respectively), says Braganca, whichWe have come so far with PhD, DEO, Dipl. ECVSMR, FRCVS, headdont get blocked or tricked by legtechnological developments that IMU of Clinical Orthopaedics at the Animalmovements. Over the years researcherssensors are becoming as accurate as Health Trust Centre for Equine Studies,have moved IMU sensor placement upOMC or, in some cases, even more in Newmarket, England.from the hooves to the legs, body, pelvis,accurate since the sensor inside the IMU In most cases slight asymmetryand withers. A commercial IMU system(the gyroscope) can measure limb angles is normal, isnt painful, and doesntcalled Lameness Locator features threedirectly, he says.affect performance. You dont havesensorsone each on the poll, pelvis, andMeanwhile, researchers at The Royal perfectly symmetrical people, Dysonone limb. Its designed to help identifyVeterinary College (RVC), in Hatfield, says. So why would you have perfectlythe lame limb, degree of asymmetry, andU.K., have come up with a method that symmetrical horses? affected stage of the stride. benefits from practical IMU technology Feedback and investigation of IMUalready available in certain smartphones. Developing Technology and Ideas systems in practice have led the UtrechtTrained veterinarians could potentially The current gold standard in objec- team to develop a similar system calledstrap a phone onto the horses hindquar-tive asymmetry exams measuring move- EquiMoves, based on eight IMU points,ters during a farm call to get a basic gait ment is optical motion capture (OMC), says Filipe Serra Braganca, DVM, a PhD candidate in equine musculoskeletal biol- An IMU system called EquiMoves is based on ogy in the Faculty of Veterinary Medi- eight inertial measurement unit points.cines Department of Equine Sciences at Utrecht. With this technology, scientists place markers all over the horses body, and a high-speed camera system detects their movement. He says one drawback to this method, though, is it can give inaccurate mea-surements when, for example, horse or handler limbs block the cameras field of view or cause errors in depth perception. This, in addition to expense and impracti-cality, has pushed scientists to find more COURTESY INGRID KERKHOVENpractical and portable ways to measure asymmetry. In recent years researchers have focused more on developing inertial measurement unit (IMU) technology, based on gyroscopes, accelerometers, TheHorse.com|The HorseNovember 201863'