ANCHORAGE, Alaska For the past five years, Alaskas annual Iditarod sled dog race has gone off mostly free of controversy, as teams of dogs and their mushers braved the elements in the 1,000-mile (1,609-kilometer) test of endurance across the frozen wilderness.

This year the deaths of three dogs during the race and five more during training have refocused attention on the darker side of Alaskas state sport and raised questions about the ethics of asking animals to pull a heavy sled for hundreds of miles in subzero temperatures.

Dog mushing has a long and storied tradition in Alaska that harkens back to its Native peoples and frontier spirit, however, and while there are calls to end the race forever, supporters say the Iditarod should remain as a celebration and reminder of a time not so long ago when the main way to travel was by sled.