Sometimes when a horse is lame in one leg, he’ll compensate by overloading another leg. The horse then can become lame in both limbs—known as compensatory lameness—which can trip up veterinarians when they’re trying to determine the source of a lameness.

Sylvia Maliye, BSc, BVM&S, MRCVS, an associate at the University of Glasgow’s Weipers Centre Equine Hospital, in Scotland, recently took a closer look at how to identify compensatory forelimb lameness related to hind-limb lameness. She presented her findings at the 2014 American Association of Equine Practitioners Convention, held Dec. 6-10 in Salt Lake City, Utah.

“Compensatory lameness is likely under-recognized and should be considered before deciding on which limb is the primary lameness source in the horse, especially in conjunction with diagnostic anesthesia (nerve blocks),” she said.

In her study Maliye used an inertial sensor system (ISS, the Lameness Locator) to objectively assess horses’ vertical head height and pelvic height at limb push-off and impact as well as limb asymmetry, which is the difference in how much a horse bears weight on a lame leg at the trot as compared to a sound limb. She evaluated 37 horses with clinical hind-limb lameness only (16), hind-limb lameness and ipsilateral (occurring on the same side) forelimb lameness (9), and hind-limb and contralateral (occurring on opposite sides) forelimb lameness. After blocking the suspected source of lameness in the hind limb with diagnostic anesthesia, she used the ISS to repeat the measurements.

Maliye said at this point she observed a significant change in head movem