Patterns of joint angular excursions, net joint moments, and power of the hind limbs have been reported1 for trotting Greyhounds and Labrador Retrievers, and it appears that there is some variability between breeds in these measures. In particular, joint motions and kinetics of the MTP and stifle joints vary between these 2 breeds, and this may be related to differences in limb conformation and gait. Whether these gross mechanical findings are related to observed differences in the composition and metabolism of intra-articular ligaments2 or to the prevalence or cause3 of cranial cruciate ligament disease remains to be determined.
When evaluating differences in gait mechanics between breeds, it is difficult to control for the effects of velocity on measured variables, and it would be good to know whether any mechanical differences observed between breeds were a result of velocity alone. Differences in relative size indicate that large dogs travelling at their preferred trotting speed will be moving faster than smaller dogs at their preferred trotting speed. Conversely, forcing various sized dogs to trot at identical speeds may mean that larger breeds are trotting more slowly relative to their body size. In another study1 conducted by our laboratory group, we allowed each dog to trot at its own self-selected speed and the handler simply maintained the direction. This yielded between-breed differences in the amplitudes of the moment and power curves; the larger, faster Greyhounds had greater ground reaction forces and shorter stance times concomitant with their faster trotting velocities, and therefore larger joint moments and powers, compared with results for the smaller, slower Labrador Retrievers. However, there were also gross differences between breeds in the shapes of the power pattern that emanated from differences in the angular motions of the joints and from differences in limb attitudes at ground contact. Therefore, the purpose of the study reported here was to investigate whether trotting speed affects the amplitudes of local maxima and minima in the joint angle, net joint moment, and net joint power patterns for various joints of the hind limbs in Greyhounds.
ProReflex, Qualisys Medical AB, Gothenborg, Sweden.
Model 9287, Kistler Instrumente AG, Winterthur, Switzerland.
Inverse Dynamics Analysis, Department of Anatomy, Faculty of Medical and Veterinary Sciences, University of Bristol, Bristol, UK.
Colborne GR, Innes JF & Comerford EJ, et al. Distribution of power across the hind limb joints in Labrador Retrievers and Greyhounds. Am J Vet Res 2005;66:1563–1571.
Comerford EJ, Tarlton JF & Innes JF, et al. Metabolism and composition of the canine anterior cruciate ligament relate to differences in knee joint mechanics and predisposition to ligament rupture. J Orthop Res 2005;23:61–66.
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Colborne GR, Lanovaz JL & Sprigings EJ, et al. Forelimb joint moments and power during the walking stance phase of horses. Am J Vet Res 1998;59:609–614.
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