Dogsled racing, more accurately referred to as sled dog racing, is a winter dog sport involving the timed competition of teams of sleddogs that pull a sled with the dog driver or musher standing on the runners. The team completing the marked course in the least time is judged the winner. Dog Sled Racing is also a fall sport where competitors use a rig ( 3-4 wheeled cart with a locking brake and handle/steering wheel) or scooter on dirt or mud instead of a sled on snow.
Races are categorised not only by distance, but by the maximum number of dogs allowed in each team. The most usual categories are four-dog, six-dog, eight-dog, ten-dog, and unlimited (also called open), although other team size categories can be found.

Racing sleddogs wear individual harnesses to which individual tuglines are snapped, pulling from a loop near the root of the tail. The dogs are hooked in pairs, their tuglines being attached in turn to a central gangline. The lines usually include short necklines snapped to each dog’s collar, just to keep the dogs in proper position. It is unusual ever to see more than 22 dogs hooked at once in a racing team, and that number is usually seen only on the first day of the most highly competitive sprint events. Dogs may be omitted from the teams on subsequent days, but none may be added. Many other rules apply, most of which have been in effect since the beginning of organised dogsled racing in the city of Nome, Alaska, in 1908.

Races:
www.up200.org - A race over 1,150 miles
www.iditarod.com - UP200 and Midnight Run
www.cb300.com - Copper Basin 300
www.racetothesky.org - Race to the Sky
www.klondike300.org - Klondike 300

www.ultimateiditarod.com/Dogsled.htm - The Anatomy of a Dog Sled
www.gomush.com - Race coverage