I don’t think there is such a thing as a greyhound-type sprint race for sled dogs. “Sprints” in dog mushing are races from 3 to 30 miles in length – up to Marathon distance for a human. Even mid-range races are 75 to 300 miles. But there are two really long-distance sled dog races in Alaska: the Iditarod Trail and the Yukon Quest. (The only other truly long-distance race is in Norway.)
The Iditarod, the older of the two Alaskan races, was initiated in 1973 as a memorial to the original Iditarod serum run in 1925. That was a dog team relay from Nenana, the closest place to Nome reachable by Alaska Railroad, to Nome, where a diphtheria epidemic was raging. The original serum run was a pony-express style relay, with the emphasis on speed and keeping the life-saving antitoxin from freezing. No one team or musher traveled the entire distance.
The memorial race was run from Anchorage, far south of Nenana, and was a race between teams and mushers going the entire distance. But the emphasis was on speed, with relatively light sleds and frequent checkpoints with food (for mushers and dogs.)
The Yukon Quest was founded in 1984 to be a different test of dogs and mushers, with mushers carrying much of the gear and food they would need to survive in the Alaskan Wilderness. There are food drops at the widely spaced checkpoints, but these must be prepacked by the musher, and no help with dogs is allowed on the trail. (The middle, mandatory rest, checkpoint is an exception, as is help from other mushers on the trail.) Sleds must be capable of carrying this extra weight, and the original idea was to replicate the dogsled mail that helped build Alaska during the gold-rush days. The race is also international, going from Fairbanks, Alaska, USA to Whitehorse, Yukon, Canada in even years, and in the opposite direction in odd years. The race is over 1000 miles in length, with substantial distances run along the Yukon River.
Although the original intent of the Yukon Quest may have been to emphasize the utility of dogs as transportation before the days of snow machines (which still are behind dogs as far as finding their way in tough weather), today’s competitive mushers not uncommonly run both long-distance races, with the same teams. In fact Lance Mackey was the first musher to win both in the same year, in 2007. Those dogs—and mushers—are tough!
All the photos I could find were copyrighted, but the Flickr site is here.