In Anchorage, Alaska, on Saturday, the "Last Great Race on Earth" begins.
Sixty-seven sled dog teams will start the 998-mile Iditarod race across the barren, frigid and unforgiving land. In this year's competition, there are a handful of first-time racers but those aren't the only rookies.
One is veterinarian Greg Reppas, whose job is to ensure the dogs are healthy throughout the race.
Days before the race, Reppas squats in a snowdrift in Wasilla and checks out Leo, one of the 16 dogs on this team that will start the Iditarod. He's a mix of husky and several other breeds and looks like a mutt. Born to run, he is raring to go. He's small like most sled dogs, just about 50 pounds.
Reppas uses a stethoscope to listen to Leo's heart. He then runs his hands across the dog's back, feeling his joints and muscles.
A few days before these exams, Leo and the 1,000 other dogs running in the Iditarod had blood work done and EKGs to check for cardiac issues. Any animal with problems is pulled and replaced before the start of the race.
These tests are just the beginning. Reppas and 50 other volunteer vets will fan out across the Iditarod's 24 checkpoints. At each one, the vets will scan the animals, sometimes taking just 30 seconds.
"When I see the dog come across the line, the first question I ask is, 'What are the problems?' So that I can emphasize my efforts on those problem dogs," Reppas says.
On the trail, it's a different kind of medicine no fancy diagnostics or elaborate tests, just a vet's expertise.
The biggest problems they see are exhaustion, dehydration and ulcers. If a dog is deemed unfit to continue, it's flown back to Anchorage for additional care. The team will keep racing but will be down a dog.
This is Reppas' first time out on the trail. He says he's ready for the challenge, partly because of his day job: He's a major in the Army. Reppas says the Iditarod is more than just a race.
"Some say these dogs are a good model for humans as far as human sports medicine," he says. "We're learning things on an annual basis on these dogs ... [and] this is the ideal laboratory to learn in."
Musher Angie Taggart of Ketchikan, Alaska, is racing in her second Iditarod.
"I always make a joke that, you know, they don't really care about the mushers because they just have the vets out there," she says. "They don't have any regular doctors. See who's important in this race? It's not the musher. It's the dog!"
For veterinarians like Reppas, the dogs are their main mission for the next two weeks. But he is also looking forward to seeing wild Alaska.
"You get that sense of perspective and how some of the locals have lived here for thousands of years," Reppas says. "You get a brief but clear look into how some folks live in this type of environment."
Bush pilots will shuttle him to remote checkpoints where he'll sleep in a tent in sometimes minus-20 degree temperatures. Like the dogs, he won't get much rest either.