ANCHORAGE, Alaska (AP) — When 57 mushers line up Sunday for the official start of the Iditarod Trail Sled Dog Race, it will be the second-smallest field in the past two decades. Only last year's field of 52 was smaller.

Interest in the world's most famous sled dog race has waned in recent years, in part because of smaller cash prizes that make it difficult for mushers to compete in an expensive sport. Animal rights activists also have stepped up pressure on sponsors to drop their support.

Now, Iditarod officials are looking to breathe new life into the competition, joining a global sled-dog ra...