ScienceDaily (Oct. 5, 2008) — Dogs are often called “man’s best friend,” and rightly so. Consider, for example, that they never interrupt us when we talk, are always happy to see us when we arrive home, and provide comfort when we are lovesick. Since dogs became domesticated 15,000 years ago, they have worked with and lived next to humans, which some say may account for the special bond. Each of the 400 breeds and varieties are unique, but only one stands out as the ultra-athlete canine: the racing sled dogs. Racing sled dogs are best known for their “mushing” each March during the Iditarod Trail Sled Dog Race, the world’s longest sled race. They are the premier ultra-endurance competitors, covering 1,100 miles from Anchorage to Nome, Alaska, sometimes in just nine days. It is unclear how they can keep running, despite heavy blizzards, temperatures as low as –40°F, and winds up to 60 mph. No other animal has been found to come close to the physiological attributes these dogs display.
– American Physiological Society. “Ultra-Endurance Competitors: Lessons From Sled Dogs In The Iditarod.” ScienceDaily 5 October 2008. 19 May 2009