The Iditarod dog sled race is an Alaskan and American institution, in which teams of dogs and people race over 1000 miles in the course of several days. It is considered a supreme challenge in endurance racing.
Most dogs I know love to work. Cattle dogs enjoy rounding up cattle. Shepherds enjoy herding sheep. My pal Buster enjoys playing fetch (which is the closest thing to work he experiences). I have always assumed that sled dogs involved in the Iditarod enjoy running the race. And perhaps most of them do.
However, two recent papers in the Journal of the American Veterinary Medical Association have made made it clear that some dogs are not benefiting from their participation in the race. The first paper discusses autopsy results of 23 dogs that died while running the race between 1994-2006.
Conclusions and Clinical Relevance–Unexpected death is a rare event among conditioned sled dogs during competition in endurance races. Potentially life-threatening conditions of dogs that are associated with periods of long-distance physical exertion include aspiration pneumonia, gastric mucosal lesions, and severe rhabdomyolysis. (J Am Vet Med Assoc 2008;232:564-573)
Translated into English, the last sentence implies that prolonged heavy breathing may cause dogs to inhale foreign matter and develop pneumonia; stress from endurance running leads to stomach ulcers; and extreme prolonged exercise may cause muscles to break down.
I should emphasize that the vast majority of dogs that compete in the Iditarod do not suffer such serious consequences. (Although if 23 humans were to die in a dozen years during a similar sized sporting event, the event would certainly be banned.) However, the second paper points out that the stress of intense training may lead to stomach ulcers and reduced red blood cell counts in a much larger number of dogs.
[A]cute blood loss secondary to gastrointestinal tract bleeding was likely responsible for the decrease in [red blood cell count] associated with acute exercise. (J Am Vet Med Assoc 2008;232:873-878)
Some people believe that running dogs in the Iditarod constitutes cruelty. I am not ready to go that far. But these articles have certainly given me something to think about.