People for the Ethical Treatment of Animals is urging sponsors of Alaska's Iditarod Trail Sled Dog Race to end their support after a dog was buried in snow by severe winds and suffocated to death.

PETA says it sent a letter to sponsors Thursday, asking them to permanently pull out of the 1,000-mile race.

Race organizers say changes are planned for care of dogs removed from the race. They say it's in response to the death of 5-year-old Dorado.

The dog was found dead at a checkpoint last week, days after it was removed from running because it was moving stiffly.

Changes planned include construction of dog shelters at two major checkpoints for withdrawn dogs and more frequent checks on the animals.

PETA has long criticized the race as cruel.