Dog sledding has changed from a survival necessity in subarctic and arctic environments to a sport. With the sporterization (I know it's not a real word) of sledding the selection has become for smaller, faster dogs and less the huge malemutes, bred to haul heavy loads long distances over the harshest environments on the planet. Racers usually own large numbers of dogs, so racing is not a sport for the poor anymore, unless they can hunt or fish sufficient food to sustain the dogs in cold conditions. Competitive racers usually have scores of dogs, some hundreds. That's a lot of kibble!
Most of the mushers I have met really love their animals, though most are in a quasi-pet status. The dogs and their masters train together and it's much like any sport. They will live or die together on their journeys through the outback. The races have veterinarians watching out for the health of the animals and great care is taken to protect them during the races. However, racing has a dark side, rarely discussed. Kind owners retire their animals when their time passes, other owners destroy these noble animals. Sometimes a musher just decides to quit the sport and it winds up in a canine massacre of all the animals. The animals rarely are raised a pets and often lack the social skills that would make them easier to adopt out. They want to stay in that zone and run with other dogs.
We lived in Alaska and I found out one of my wife's co-workers did just that with dozens of dogs. I had to restrain myself around her to avoid telling her what I thought about her. As my wife and I were driving through Canada once the radios were abuzz with the news that another retiring musher had killed over a hundred dogs. People need to think before they get into the sport what is the end game for the animals without which there is no race.