The Horse

NOV 2018

The Horse:Your Guide To Equine Health Care provides monthly equine health care information to horse owners, breeders, veterinarians, barn/farm managers, trainer/riding instructors, and others involved in the hands-on care of the horse.

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62 November 2018 The Horse | TheHorse.com STEP BY STEP TheHorse.com/Step-By-Step CHRISTA LESTÉ-LASSERRE, MA S ometimes it's painfully obvious. Your horse takes a long step, then a short one, then a long one, then a short one. His head bobs, and his ears pin. You're experienced enough to know he's lame on the front leg that's down when his head bobs up, or the opposite hind. But what if it's two limbs, or three? What if your horse isn't overtly lame but is not performing well or has developed de- fensive behaviors like biting or bucking? Recognizing lameness is no easy task. That's why some equine veterinar- ians train for years to become lameness experts, evaluating horses with their eyes, hands, knowledge, and experience. That's also why various research groups across the globe have turned to technology to help quantify lameness where they can't. These measurement systems detect the slightest asymmetry in individual limb movement, providing objective data that veterinarians can use for diagnosis and comparison. Objective measurement systems can be precise and highly sensitive. But so can well-trained veterinarians carrying out subjective evaluations. As objective sys- tems start filtering into the 21st century commercial market, the question arises: For lameness exams, which is better— human, machine, or both? The Challenge: Finding the Source Lameness isn't easy for us to pre- cisely detect. It's not even easy for equine veterinarians to detect. That's especially true for less experienced veterinarians, says Marie Rhodin, PhD, Dipl. ACVSMR, associate professor in equine clinical biomechanics at the Swedish University of Agricultural Sciences, in Uppsala. In a recent study Rhodin's team cre- ated temporary lameness in a group of horses by tightening a screw in a shoe on a randomly selected foot, making the sole slightly sore. Then they filmed these lame horses, as well as clinically lame and sound horses, trotting in a straight line and circling on a longe line in both directions. A group of 86 equine orthope- dic clinicians of varying experience levels viewed the videos and commented on them. Their level of agreement with each other was "very poor" overall, Rhodin says, with the greatest differences noted among the less experienced clinicians. They disagreed about which limb was lame, and their evaluations of lame versus sound horses also varied. Those discrep- ancies were even more pronounced with subtle lameness cases. Asymmetry vs. Lameness Objective systems don't measure "lameness," per se. Rather, they measure asymmetry. But is a lame horse an asym- metrical horse and vice versa? "Asymmetry isn't lameness," says Paul René van Weeren, DVM, PhD, Dipl. ECVS, professor in the department of equine sciences at Utrecht University, in the Netherlands. "It can be a sign of pos- sible lameness, but its presence doesn't mean a horse is lame." Such confusion can create issues for a competitive rider, for example, who might face penalties, disqualifications, and public criticism for riding a horse that's asymmetrical and, therefore, assumed to be "lame." Movement asymmetry can occur for a variety of reasons, Rhodin says. It could be "mechanical"—meaning it's how the horse is naturally, without any pain. It can also be induced by turning circles, which by their very nature make horses ISABELLE ARNON Lameness Exams: Subjective or Objective? When it comes to evaluating lameness with man or machine, the best outcome might involve both Source and degree of lameness can be difcult for even the most seasoned veterinarian to detect.

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