Even experts can’t diagnose subtle lameness as accurately as this new tool.
BY JOAN NORTON VMD, DACVIM
Lameness in your performance horse can be a frustrating setback. Subtle lameness or vague, undiagnosed poor performance can be exasperating, and the longer diagnosis is delayed by uncertainty, the longer the time to treatment. Traditional lameness exams rely on an experienced veterinarian’s eye to detect changes in the horse’s gait. Not only do clinicians need to identify that the gait is abnormal, they must also determine which limb is affected—something not so simple, especially when dealing with hind-limb lameness. But even though there are standardized grading scales for lamenesses set out by the American Association of Equine Practitioners, when subtle abnormalities are present there is often disagreement between the evaluations of experienced equine veterinarians.
To combat the low reliability and potential bias of subjective exams, scientists have developed objective ways of measuring lameness. Force-plates, recessed into the floors of veterinary clinics, force-sensing treadmills, and specialty force-measuring shoes have been used to detect changes in the amount of pressure exerted by each limb as a horse jogs. While these are considered the gold standard in evaluating lameness they are not readily accessible. Horses may have to travel long distances to a clinic that has such technology.
Now researchers and veterinarians are turning to advanced mechanics employed by the aerospace and automotive industries. Developed by veterinarians at the University of Missouri and produced by Equinosis LLC, the Lameness Locator® uses inertial sensors (gyroscopic accelerometers) to detect asymmetry in a horse’s gait. Three small, lightweight sensors are placed on the horse. One is attached to the halter, one wraps around the pastern, and a third is placed on the top rump. These pieces record movement of the horse at each location.
The data is wirelessly transmitted to a laptop that uses complex algorithms to determine the location and severity of lameness. The accuracy of it is similar to the gold-standard force plate analysis.
When compared to three seasoned equine veterinarians, the Lameness Locator was able to detect mechanically-induced lameness at a much subtler level than the trained naked eye. Horses were fitted with shoes containing a screw that applied pressure to the sole at increasing intensities, producing a lameness that worsened with each turn of the screw. The inertial sensors identified the lameness at a much earlier stage than the practitioners. This higher sensitivity was apparent regardless of front or hind limb lameness or whether the lameness was induced with toe or heel pain.
The Lameness Locator will be invaluable for mild lameness, multiple-limb lameness, and lameness secondary to another injury. It can also be part of the ever important pre-purchase exam to detect lameness not apparent to the naked eye. While nothing will completely replace the complete lameness exam that your veterinarian can provide, the Lameness Locator can bring these exams to the next level, identifying problems sooner, leading to better treatment and a faster return to the ring.