Dogs have a great variety of shapes and sizes. Skull shape, trunk shape and limb shape and length reflect what a dog can do; their capacity to feel, their capacity to express, whether they are introverted or extroverted in giving form, and how they move.
For example a Greyhound moves primarily with their back muscles and gives an emotional expression when they run. Great Danes primarily use their belly or underside muscles to walk and run, feeling themselves and their surroundings as they move. Poodles and collies are beautiful in their form and Golden Retrievers are social extroverts.
The differences in movement for a particular breed are a manifestation of which muscle chain is the primary or dominant muscle chain used for movement. A Greyhound moves primarily using the back muscles on either side of the spine. Body shape and skull shape predict which muscle chain or chains are dominant in a particular individual.
Pomeranians and Pekingese, using intevertebral muscles, have a dancing happy gait. Problems in locomotion or frustrated or difficult behaviors can result if a dog is suppressed in their natural movement and exploration during their critical development. Safety to develop naturally results in stability for them to be, behave and move in a manner that is natural for them.
The differences in movement between breeds are, in part, a manifestation of which muscle chain is the natural primary or dominant muscle chain used for movement and self expression by that breed.