Racing underway in Alaska's sled dog race

Teams are racing in the snow in the Iditarod Trail Sled Dog Race across Alaska.
Teams are racing in the snow in the Iditarod Trail Sled Dog Race across Alaska.

Big crowds have converged on Alaska's largest city as hundreds of dogs and their humans kicked off the 47th running of the Iditarod Trail Sled Dog race with a ceremonial sprint along snow-heaped streets.

The fan-friendly event in Anchorage brought spectators up close to the 52 musher-dog teams gearing up for the famed 1,609 kilometre race on Saturday.

Mushers are generally more relaxed here than they will be for the real thing. But the dogs barked furiously before setting off, jumping and straining against their sled lines in apparent excitement to get going on the 18km dash.

The serious, competitive portion of the wilderness trek starts Sunday in the small community of Willow, north of Anchorage. From there, the 14-dog teams will cross two mountain ranges, the frozen Yukon River and dangerous sea ice along the Bering Sea Coast. Village checkpoints are staged across the trail before the teams reach the finish line in the old Gold Rush town of Nome on the state's western coast.

The winner is expected in Nome in about nine days. The expected top prize is $US50,000 ($A70,625).

The race comes after two difficult years for organisers marked by a dog-doping scandal, the loss of big-name sponsors and escalating pressure from animal activists over multiple dog deaths.

Australian Associated Press