DENVER -- The head of the American Humane Association responded Tuesday to news reports about an Aspen-based sled dog operation which shoots dogs in the back of the head to "cull" them.

Dan MacEachen, the owner of Krabloonik kennels in Snowmass Village has admitted using the practice to kill older dogs at the end of their working lives or pups that are incapable of pulling a sled, but he said the practice is legal under Colorado law.

"While Colorado law does not outlaw gunshot as a form of euthanasia, there is a difference between what a person is legally bound to do for an animal in their care, and what they are bound to do by their own conscience," said Marie Belew Wheatley, the head of the American Human Association. "It is inconceivable to me that a business enterprise that profits off the work and loyalty of these dogs would fail to seek another more compassionate end for these animals."

There are about 250 dogs in 30-year-old Krabloonik's operation, which takes Aspen tourists on sled rides and then feeds them at a restaurant near its kennels.

Tammy Vanderpol, the office manager for Krabloonik's, said the situation has been blown out of proportion.

"We're all dog owners here," she told the Aspen Times.

The practice of shooting dogs in the head and burying them in a pit filled with dog feces is not the norm in the sled-dog industry, according to sled-dog operations contacted by the Aspen Daily News.

Martin Buser, an Iditarod veteran and four-time winner of the Alaska dog sledding race, told the News that the practice of euthanizing dogs by gunshot is no longer used by his Happy Trails Kennel. He has not had to euthanize a single dog in several years, he said, and when he does he calls a veterinarian to administer a lethal injection.

Buser said that when his sled dogs die, they are buried in special graves along established trails as a "sort of honor" that people pass on a daily basis.

MacEachen told the News that the number of dogs killed at Krabloonik's each year varies, but it is much lower than the 35 dogs referred to by a former employee.

"It's not too often that we have had to do that," MacEachen told the paper.

Although MacEachen calls his operation the largest of its kind in the United States, Plettner Kennels in Alaska runs 300 dogs -- 50 more than Krabloonik. The owner, Lynda Plettner, has started up a nonprofit called Alaska's Iditarod Sled Dog Retirement Foundation. It is a retirement program set up specifically for Iditarod veteran dogs.

"There is no other animal in the world like them, and based on that fact alone, they deserve to continue to receive the best care possible long after their competitive days are over," said Plettner on her Web site.

She told the News that every dog at her kennels has a home up to the day they die.