She wants to determine how dogs fuel themselves during the canine marathon

By Mary Ann Albright
CORVALLIS GAzette-times

Called “the last great race on Earth,” the Iditarod Trail Race pushes mushers and sled dogs to the limit. Teams race more than 1,150 miles across tough Alaskan terrain from Anchorage to Nome competing for their share of a nearly $800,000 purse and the glory of victory.

It’s an ordeal that requires large amounts of energy from the sled dogs, and Oregon State University veterinarian Erica McKenzie has spent the past four years studying how the dogs fuel themselves during this canine mega-marathon.

McKenzie, 32, suspects that the dogs stop using muscle glycogen (the chemical that is the principal storage form for glucose in animal cells) after the first day of racing, and then tap into other sources, including blood globulin, for energy.

“On day one, muscle glycogen drops to about 30 percent of pre-exercise levels. On subsequent days, the dogs rely much less on it, and probably draw on protein and fat instead,” said McKenzie, an assistant professor of internal medicine in OSU’s College of Veterinary Medicine.

Globulins are a series of proteins in the blood that protect against infectious disease. Muscle glycogen is broken into glucose, a key energy source.

In human athletes, once glycogen levels are depleted, the body begins to fatigue, McKenzie said. But that doesn’t seem to be true with sled dogs, she said, which seem to be able to sustain themselves, probably by burning protein and fat.

Today McKenzie left for Alaska to continue her research, which could have broader implications for human athletes and could shed some light on public-health issues. This is McKenzie’s second trip to the Iditarod. She’ll stay in the Last Frontier through March 19, taking blood samples from dogs that successfully complete the race and comparing globulin levels to the dogs’ pre-race lab tests.

McKenzie wants to study how prevalent depleted globulin levels are among the dogs, and what the consequences of low globulin might be on the animals’ immune systems.

“The majority of these dogs appear healthy and finish the race, so it doesn’t appear there are adverse effects,” she said.

Still, McKenzie will investigate whether there’s a correlation between instances of respiratory disease and intestinal upset and depleted globulin levels.

The research is funded by the American Kennel Club’s Canine Health Foundation. Joining McKenzie in Alaska are Stuart Nelson, head veterinarian for the Iditarod, Kenneth Hinchcliff, a veterinary professor at Ohio State University who recently was named dean of veterinary medicine at the University of Melbourne in Australia, and Heidi Banse, a veterinary student at Washington State University.

When McKenzie returns to OSU, Manoj Pastey, assistant professor of virology and immunology, will help her process the blood samples.

The Iditarod began March 3, and the winning team is expected to finish around March 12.

McKenzie plans to return to Alaska three or four months after the race to get blood samples from the dogs once they’ve recovered, and determine if the exertion had any long-term effects on their globulin levels.

McKenzie, a native of Australia, began her sled-dog research at Oklahoma State University with Dr. Michael Davis. Her work there was funded by the U.S. Department of Defense, which was interested in endurance studies.

Military officers aren’t the only ones wanting to know whether humans might be able to learn something from sled dogs.

McKenzie has been contacted by triathletes curious as to whether they too could tap into other energy sources when their glycogen runs low.

Humans running in a marathon work at a higher intensity than sled dogs, so they’re more dependent on muscle glycogen than protein or fat, McKenzie said. Also, the dogs eat very high-fat, high-protein diets, while humans eat more carbohydrates.

All kinds of breeds

Iditarod teams begin with 16 dogs, and must finish with at least five. McKenzie said most people are surprised to learn that a variety of breeds, not just Siberian huskies, make good sled dogs.

She even knew of one musher who raced with a team of standard poodles for several years, although they didn’t prove themselves ideal sled dogs.

Sled dogs are often mixed breeds that are part hound or pointer, she said. The “wheel dogs” — the ones closest to the sled — usually weigh 60 or 70 pounds, but the lead dogs and the ones in the middle of the line may be as light as 30 pounds.

With the sled, food, equipment and the musher, the dogs are pulling about 250 pounds, McKenzie said. The dogs can travel 10 to 12 miles per hour, but usually stick closer to 7 or 8 miles per hour for the majority of the race.

The race includes mandatory rest periods and health checks along the route to make sure the dogs are healthy and aren’t being pushed too hard, McKenzie said.

McKenzie’s research is important from public health and animal safety perspectives, according to Pastey, the OSU assistant professor.

After the Iditarod, globulin levels may be depleted to the point where the dogs, which come from all over the world, are more susceptible to infectious disease.

Sick dogs could spread illness to other dogs and their handlers, Pastey said, adding that knowing dogs’ globulin levels is important in managing their diets and vaccinations.

Mary Ann Albright covers higher education. She can be reached at maryann.albright@lee.net or 758-9518.