In this March 15, 2016, photo, Dallas Seavey poses with his dogs Reef, left, and Tide after finishing the Iditarod Trail Sled Dog Race in Nome, Alaska. Four of Seavey’s dogs that competed in this year’s Iditarod tested positive for a banned substance, race organizers said this week. (Mark Thiessen/AP)

Dogsledding has become the latest professional sport to be involved in a doping scandal, this one involving the huskies that dash across the frozen landscape in Alaska’s grueling, 1,000-mile Iditarod.

The governing board of the world’s most famous sled dog race revealed Monday that four dogs belonging to four-time Iditarod champion Dallas Seavey tested positive for a banned substance, the opioid painkiller tramadol, after his second-place finish in March.

It was the first time since the race instituted drug testing in 1994 that a test came back positive.

Seavey strongly denied giving any banned substances to his dogs, suggesting that he may have been the victim of sabotage by another musher or an animal rights activist. He accused the Iditarod of lax security at dog-food drop-off points and other spots.

Race officials said he will not be punished because they were unable to prove he acted intentionally.

But the finding was another blow to the Iditarod, which has seen the loss of major sponsors, many dog deaths, attacks on competitors and pressure from animal rights activists, who say huskies are run to death or left with severe infections and bloody paws.

Jeanne Olson, an Alaska veterinarian who treats sled dogs, sees no benefit in administering tramadol during a race because it causes drowsiness. Olson, who was the head veterinarian in the Yukon Quest International Sled Dog Race in the 1990s, prescribes it mostly for profound pain relief.

“But I also caution that the dogs are going to become sedated from it,” she said. “So when I first heard . . . that it was tramadol as the drug, I thought, ‘Well, that’s surprising. Why would anybody use that?’ ”

People for the Ethical Treatment of Animals (PETA) seized on the scandal Tuesday, saying it’s “further proof that this race needs to end.”

Dogs are subject to random testing before and during the race, and the first 20 teams to cross the finish line are automatically tested.

“I did not give a drug to my dog. I’ve never used a banned substance in the race,” the 30-year-old Seavey said in an interview.

Five dogs connected to this year’s race died, bringing total deaths to more than 150 in the Iditarod’s 44-year history, according to PETA’s count.

— Associated Press