The metabolic strategy of sled dogs is a mystery, as reported by the New York Times

Dr. Michael S. Davis, an associate professor of veterinary physiology at Oklahoma State University and an animal exercise researcher, said: “Before the race, the dogs’ metabolic makeup is similar to humans. Then suddenly they throw a switch — we don’t know what it is yet — that reverses all of that. In a 24-hour period, they go back to the same type of metabolic baseline you see in resting subjects. But it’s while they are running 100 miles a day.”

Humans get tired after repeated strenuous activity that depletes fat stores. We have to shut down and rest. The dogs seem to escape this, which is why DARPA has funded Davis to figure out why and how.

If Dr. Davis and the Texas A&M researchers identify the biomarker, or “switch,” that could help the military understand and develop ways to control and prevent the physiological effects of fatigue in strenuous cases like combat.

“Soldiers’ duties often require extreme exertion, which causes them to become fatigued,” Jan Walker of Darpa wrote in an e-mail message. “Severe fatigue can result in a compromised immune system, making soldiers more susceptible to illness or injury.”

Although this sounds magical, Dominique Grandjean (DVM, PhD, HDR Colonel, Chief veterinarian, Paris Fire Brigade Professor, Alfort National Veterinary School Head of Canine Breeding and Sport Medicine Unit) gave a presentation called “Racing sled dogs most frequent health problems” that might suggest otherwise. It lists the top five reasons given for dropping dogs during Iditarod and the number one slot is fatigue. Slide 12 says “Stress a key word for sled dogs” and calls out metabolic stress as well as cellular stress. Later in the presentation she discusses early fatigue. Thus, even if they can harness the magic of sled dogs DARPA still will need to deal with fatigue and stress symptoms.