CORVALLIS, Ore. – Sled dogs racing at the annual Iditarod in Alaska expend an extraordinary amount of energy during the 1,150-mile race and an Oregon State University researcher is part of a team that will study whether the dogs tap into a hidden reservoir of fuel.

Erica McKenzie, an assistant professor in OSU’s College of Veterinary Medicine, will study the dogs’ blood globulin levels to determine how depleted they become during the race.

“Sled dogs have comparatively low globulin levels during training, and those levels fall considerably during racing,” said McKenzie, a veterinarian who specializes in internal medicine. “The dogs stop using muscle glycogen after the first day, and our theory is that they tap into blood globulin as an additional energy source.

“When human marathoners run out of glycogen, they hit the wall,” she added. “When racing dogs run out, they seem to find another source and we think blood globulins may comprise part of that source.”

The research is funded by the American Kennel Club’s Canine Health Foundation as part of an ongoing effort to promote the health of dogs.

McKenzie has worked with racing sled dogs for the past four years, including teams run by five-time Iditarod winner Rick Swenson. During the race from Anchorage to Nome, dogs burn an enormous amount of energy, requiring 4,000 to 6,000 calories a day. And some of the dogs weigh as little as 30 pounds, she pointed out.

“Pound for pound, their energy requirements are several times that required by Tour de France (bicycle) riders,” McKenzie said.

Contrary to popular belief, the majority of the sled dogs aren’t purebred huskies. They often are mixed breeds that include hounds, pointers and other breeds. One musher even ran a team of standard poodles in previous years of the race.

Blood globulin is produced by the body to protect against infectious diseases, though most racing dogs don’t appear to suffer from any adverse effects because of low levels, McKenzie said. Different “fractions” of the globulin have different characteristics, she added. One portion protects the respiratory system, another helps fight parasites, while at least two others primarily protect against infectious diseases.

The research goals include documenting the dogs’ blood globulin levels, checking for any adverse effects of low globulin, and determining if blood globulin is used as an extra energy source.

McKenzie will work with OSU veterinary medicine colleague Manoj Pastey, an immunologist; Stuart Nelson, head veterinarian for the Iditarod; and Kenneth Hinchcliff, a veterinary professor at Ohio State University who recently was named dean of veterinary medicine at the University of Melbourne in Australia.

More information on the Iditarod is available at:

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Erica McKenzie,