Flyball is a relay race with 4 dogs on a team. The course consists of a  start line, 4 hurdles spaced 10 feet apart and a box. The first hurdle is 6 feet from the start line and the box is 15 feet from the last hurdle for a 51 foot overall length. The dog jumps the hurdles and steps on a spring loaded box that shoots out a tennis ball. The dog catches the tennis ball and then runs back over the hurdles. When the dog crosses the starting line the next dog goes. The first team to have all 4 dogs run without errors wins the heat. Any breed of dog or size can play. All participating dogs should be at least 7 months old and not older than 7 unless they are already engaged in sports, such as agility. Dogs should be physically sound (no hip or leg problems) and not dog, or people aggressive. They should have basic obedience skills, including recall.