Flyball is the sport of relay racing for dogs. Each dog on a flyball team has to jump 4 hurdles, trigger a specially designed box causing a ball to be ejected, catch the ball, and return over all four hurdles to the handler. If the dog faults by missing a jump, not triggering the box, or failing to carry the ball all the way past the finish line, the dog will have to rerun at the end of the line, incurring a time penalty for the team.
Four dogs race on a team; teams race against each other for their standings in a tournament, and they race against the clock for points toward titles.
Diagram below courtesy of Decatur daily: