Meeting Abstract

P3.131  Monday, Jan. 6 15:30  Dog gait on rough terrain: When does static stability matter? REEVE, MA*; WILSHIN, S; SPENCE, AJ; Royal Veterinary College mireeve@rvc.ac.uk

Most legged animals need to traverse uneven terrain. This task is important as safe and economical traversal of rough terrain can impact reproduction, feeding and survival. One way to facilitate this task may be to adjust the relative leg timings of a particular gait. In previous work we have shown that changes in gait at walking speeds on rough terrain agree with predictions made by a model based on static stability considerations. In the present study we compare trotting behavior on flat and rough terrain. Six dogs of withers height 507.5±66.3 mm (means±s.d.) and body mass 22.6±4.5 kg were fitted with a sensor suite, comprised of GPS and inertial measurement units, and trialed over flat versus rough terrain. With sensors attached to the proximal-most leg segment and the withers, we measured animal speed, position and a continuous estimate of leg phase. We filtered the data to include strides at similar speeds. Speed was not significantly different in any of the subjects between terrain types (filtered data; Mann-Whitney U-test, p>0.05; n=3 to 20 strides, median=10.5). On the rough terrain, stride frequency was significantly lower in five of six dogs, and for one of these dogs stride length was significantly higher (Mann-Whitney U-test, p<0.05). In addition, a static-stability inspired model fit to data in our past work led us to hypothesize that at trotting speeds, the gait would become more walk-like on the rough terrain. Here we show that this does not appear to be the case (linear mixed-effects model; n=6 dogs, p>0.05; n=3 to 20 strides, median=10.5). We conclude that trotting speeds are outside of the domain of validity of our model; this may be a result of the model relying on considerations of static stability at speeds where energetic and dynamic stability dominate.