The aim of this study was to describe the motion pattern of the sound dog during walking using kinematic analysis and surface-electromyography.
For an objective exclusion of lameness ground reaction forces were measured after the dogs had been clinically and orthopedically examined according to BAUMGARTNER (2005) and BRUNNBERG (1998). Four Golden Retrievers, four Labrador Retrievers, two Australian Shepherds and two Border Collies with a mean body mass of 25,9 ± 5,0 kg were included in this study. Five of them were female and seven were male dogs. Their mean age at the time of measurement was 4,7 ± 2,1 years. Light reflective markers were fixed on the skin above selected touchable bone points of the right hind limb. The surface electrodes were placed on the shaved and cleaned skin above the M. biceps femoris (cranial part) and M. gluteus medius. The data was processed with EVaRT (Version 5.0.4, Motion Analysis Corp.), Microsoft Excel (Microsoft Office 2007 for Windows), MatLab (Version 18.104.22.1687 (R2007a)) and SIMI Motion 6.5 (SIMI Reality Motions Systems, Unterschleißheim, Germany).
The activity pattern of the M. biceps femoris in walking dogs consists of one maximum of 46,7% ± 6,6%[Delta]MM at the passage of the swing to stance phase at 37,8% ± 9,0% BZ. There is a strong correlation to the maximum of extension of the stifle joint with 17,7° ± 3,3° at 40,8% ± 2,2% BZ.
The M. gluteus medius shows an activity pattern with two maxima. The first one with 42,9 ± 6,1%[Delta]MM takes place at the beginning of the swing phase at 8,7 ± 7,4% BZ, where the hip also has its maximum of extension. A correlation coefficient of 0,97 is shown at this time of the motion cycle. At the passage of the swing to stance phase the hip joint shows maximal flexion, whereas the muscle is already activated.
The second peak of activity of the M. gluteus medius with 37,9 ± 7,1%[Delta]MM was found during the first part of the stance phase at 52,3 ± 14,1% BZ, where the hip joint is still flexed. Because of the different curve progression the correlation coefficient is strongly negative (-0,70). During the second part of the stance phase the hip joint correlates clearly (0,90) with the M. gluteus medius. The muscle is active and also the hip starts to extend. This study has a potential clinical relevance not only for research in different kind of orthopedic or neurological diseases but also for the development of biomechanical models, for example artificial limbs. The results can also be used as a checkup in the sector of physiotherapy.