HOW DO THEY WORK
They work by pronking! Pronking: the animal gait when all four feet leave the ground at the same time.
These pugs are majestic like deer.
M. Hillebrand. 1989. The quadrupedal gaits of vertebrates: the timing of leg movements relates to balance, body shape, agility, speed and energy expenditure. BioScience 39:11 766-775.