Before sled dogs can compete in the John Beargrease Sled Dog Marathon, they have to be cleared by vets to ensure they can handle the race.

WDIO-TV  reports that University of Minnesota students who are studying to become veterinarians gave the dogs check-ups Saturday morning. Up to 500 dogs were examined Saturday.
"We're listening to their heart rates, listening to their lungs, we're looking for any, you know, rubs that they might have from their training on their feet or their harnesses. Just checking their attitudes, their hydration, their gum color. We're trying to make sure that all of those things that could cause trouble on the trail are caught ahead of time," said Gregg Phillips, the race's head veteran.
Phillips said the check-ups are a great experience for the students, who will take care of the dogs throughout the race. He said many veterinarians come back year after year to help.
The Beargrease starts Sunday and runs through Jan. 29.
Martha Schouweiler, a four-time winner of the Beargrease's Mid-Distance Marathon, said the dog's do better in the cold. In warmer temperatures, like this year, a musher might want to stop the team more often to give the dogs water or a snack.