April 12, 2006 — Labradors and dachshunds appear to waddle, while greyhounds seem to march by with a fast clip, but new research has determined that the basic mechanics behind dog walking are the same for all canines.

The discovery could lead to a better understanding of health issues related to walking in dogs, such as hip problems. It could also result in improvements to four-legged, dog-like robots, which the U.S. military already is investigating.

"The big benefit would be to show how robot dogs should walk more efficiently," said lead scientist Jim Usherwood, a researcher at the University of London's Royal Veterinary College Structure and Motion Laboratory.

Usherwood added, "Almost all robots require a large amount of power — much higher than an animal would use — partly because they tend to use bent legs. I show what would happen with stiff legs."

Inspired by stiff-legged mechanical toys that can walk down hills, Usherwood and his team designed several different computer models for dog walking. The researchers then compared these models with observations of actual dogs on a treadmill.

Their simple, passive, stiff-limbed computer model best matched and explained the principles underlying dog walking.

The findings were recently presented at the Annual Meeting of the Society for Experimental Biology.

Walking for both bipeds and quadrupeds is like controlled falling because, with each step, the individual leans forward and is "caught" by an outstretched limb. As a result, there is a stage when the body is high and slow, and a stage when the body is lower and faster, Usherwood explained to Animal Planet News.

"With a four-legged animal, this has broadly been observed before, but it had not been clear why and when these motions should happen," he said. "My passive model makes it much easier to understand when and why the body moves up and down and changes in speed."

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