Veterinarians are frequently asked to examine horses for lameness in more than one leg, a condition referred to as multi-limb lameness. “If you have a lameness in one leg, the horse will often shift its weight, and this can make another limb appear lame,” said John F. Marshall, BVMS, PhD, MRCVS, Dipl. ACVS, ECVS, of the University of Glasgow School of Veterinary Medicine’s Weipers Centre Equine Hospital, in Scotland. This, of course, can make diagnosing the source of the problem difficult.

To help veterinarians determine which limb is the source of the lameness, Marshall and colleagues evaluated 28 horses with naturally occurring forelimb lameness caused by a variety of issues, including navicular syndrome, coffin joint arthritis, and tendon and ligament issues.

They determined that these forelimb lamenesses resulted in significant compensatory load redistribution.

“Forelimb lameness reduces the push-off from the opposite hind limb, which looks like lameness,” Marshall explained. “For example, a left forelimb lameness would cause a false ‘lameness’ in the right hind limb,” caused solely by the horse shifting its weight away from pain in another limb.

While compensatory load redistribution in itself does not harm the horse, this phenomenon can be misleading to both veterinarians and owners, which can cause incorrect or delayed diagnoses.

“Whenever a vet performs a lameness exam, it is important that they always examine the horse as a whole before focusing on a particular leg,” Marshall said.

To increase the rate of successful diagnosis, Marshall recommends veterinarians also examine the hind limbs for lameness when they observe a forelimb lameness. If a hind limb lameness on the opposite side is present, then the forelimb lameness is most likely the main problem, he said. However, if the hind limb lameness is on the same side, chances are the hind limb lameness is actually the main problem, he said.

The study, “Naturally-occurring forelimb lameness in the horse results in significant compensatory load redistribution during trotting,” will appear in an upcoming issue of The Veterinary Journal