For the first time in the history of the world's most famous sled dog race, several of the high-performance animals have tested positive for a prohibited drug. But race officials have refused to name the musher involved.

Several dogs tested positive for the opioid pain reliever Tramadol, the governing board of the Iditarod Trail Sled Dog Race said in a statement. The team was tested six hours after finishing the nearly 1,600-kilometre race in Nome in March, officials said. They estimate the drug could have been administered up to 15 hours before the test was done.

Iditarod spokesperson Chas St. George said in an email that the musher's name is not being released based on a lawyer's advice.

He said the musher also has not been named because race organizers would have trouble proving the musher intentionally administered the drug.

St. George said the musher will be allowed to participate in next year's race and will not face any disciplinary actions.

iditarod

A team pulls off the sea ice for the final stretch of the 2017 Iditarod, last March. The first 20 teams to reach Nome are routinely tested for doping. (Mike Kenney/Iditarod Trail Committee/Associated Press)

Iditarod board member and musher Aaron Burmeister said Wednesday he doesn't know the musher's identity. However, only the first 20 teams to reach Nome are tested, he noted.

Everyone seems guilty as long as the affected team remains unknown, said Burmeister, an Iditarod contender who sat out the past two races.

"It's not a good situation," he said Wednesday. "I'm hoping that we can turn a positive light on it and the musher steps forward."

Hot topic among mushers

The Iditarod began testing sled dogs for prohibited substances in 1994. Dogs on all teams are subject to random testing between pre-race examinations and along the race trail. Testing in Nome for top finishing teams, however, is not random but expected.

As a result of the positive test findings, the race rule dealing with canine drug use was revised earlier this month to hold mushers liable for any positive tests in future races unless they can prove the results occurred outside their control. Previously, the rule could be interpreted to require that race officials provide proof that a musher intended to administer the prohibited substance.

Iditarod Dog Race

Aaron Burmeister lays down straw for his team in the 2015 Iditarod. He says the doping is a hot topic among fellow mushers. (Loren Holmes/Alaska Dispatch News/Associated Press)

The doping is a hot topic among fellow mushers, Burmeister said.

As to why a musher would give dogs prohibited drugs when testing is expected in Nome, there has been speculation that perhaps a competitor could have administered the drug. Mushers fly their team's dog food to checkpoints along the trail up to two weeks in advance, and it sits there until mushers arrive at the checkpoint and use it.

But Burmeister isn't buying that theory. "As a musher, why would another musher give their competitor a performance-enhancing drug?" he said.

Burmeister said several times in a phone interview that no other dogs have ever tested positive in the race.

"I just hope that people look at the big picture and realize that mushers out there are not doping their dogs," he said. "This is an isolated incident."