Researchers Study Compensatory Lameness

Compensatory lameness is likely under-recognized and should be considered before deciding on which limb is the primary lameness source, Maliye said.

Photo: Anne M. Eberhardt/The Horse

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 movement and asymmetry in the ipsilateral group.

“In 78% of cases there was significant change to the asymmetry of the ipsilateral forelimb," she said. In other words, the ipsilateral forelimb improved noticeably with diagnostic anesthesia of the hind limb.

"These included horses with evidence of hind-limb lameness only and those with evidence of hind-limb lameness concurrently with ipsilateral forelimb lameness," as determined by the ISS, she said. In other words, Maliye and her colleagues showed that a veterinarian can expect to see a change in vertical head movement or gait asymmetry in the ipsilateral forelimb of a hind-limb-lame horse, whether there’s an actual lameness in the forelimb or not.

In the contralateral group, however, "No significant changes to the contralateral forelimb lameness were noted after nerve blocking the hind limb, which implies that likely represents true forelimb lameness rather than being compensatory,” she said.

In summary, Maliye said that in more than a quarter of hind limb lameness cases, it's not uncommon to see forelimb lameness on the same side as the lame hind leg, which might well be compensatory only, without any forelimb pathology.

About the Author

Nancy S. Loving, DVM

Nancy S. Loving, DVM, owns Loving Equine Clinic in Boulder, Colorado, and has a special interest in managing the care of sport horses. Her book, All Horse Systems Go, is a comprehensive veterinary care and conditioning resource in full color that covers all facets of horse care. She has also authored the books Go the Distance as a resource for endurance horse owners, Conformation and Performance, and First Aid for Horse and Rider in addition to many veterinary articles for both horse owner and professional audiences.

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