NIKOLAI, Alaska — Iditarod sophomore Scott Janssen was making his way down a steep section of the Dalzell Gorge when the dog collapsed.

One moment, 9-year-old Marshall was pulling hard at the sled, the tug line taut as a guitar string. The next, the husky was on the ground.

“Boom! Laid right down. It was like a guy my age having a heart attack,” said Janssen, who owns an Anchorage funeral home and calls himself “The Mushing Mortician.”

Janssen raced to the dog. Marshall did not appear to be breathing, he said.

“I know what death looks like, and he was gone. Nobody home,” Janssen said.

Dog deaths are a constant fear for Iditarod mushers and boosters. Critics point to the once-common fatalities along the trail as evidence the race is inherently inhumane. But no dogs have died in the past two years and racers are eager to continue the trend.

For many mushers, sled dogs are some combination of co-worker and employee, friend and family member.

“I was sobbing,” said Janssen, who began a kind of mouth-to-snout CPR — compressing the husky’s chest and breathing into his nose. “I really love that dog.”

Marshall collapsed late Monday night as the musher navigated a famously tricky section of trail that follows Rainy Pass as mushers exit the Alaska Range. Janssen, who turns 51 on Monday, is running his second Iditarod after placing 42 of 47 finishers last year.

Janssen trains with Iditarod rookie Anna Berington, running dogs from 1984 Iditarod champion Dean Osmar’s kennel in Kasilof.

Marshall is likely one of the oldest. He has finished maybe half a dozen Iditarods, mainly with Kenai Peninsula musher Paul Gebhardt. This was to be the dog’s last trip to Nome, Janssen said.

The musher spent the next few crucial minutes attempting a kind of dog rescue technique taught to him by Gebhardt. Janssen tucked the dog’s tongue into its mouth and held the mouth closed.

“I had my mouth over his nose, breathing into his nose as I was compressing and rubbing his chest, trying to work the air out,” Janssen said.

After what seemed like an eternity but was likely no more than five minutes, Janssen talked to the dog, he said. “I’m like ‘c’mon dude, please come back.’

“And he did.”

The dog suddenly hacked a breath, Janssen said.

The musher said he doesn’t know why Marshall collapsed. Maybe heart arrhythmia, he guessed.

Janssen carried Marshall in his sled until the Rohn checkpoint about 32 miles from Rainy Pass, breaking a runner along the way.

“The vets took a look. Gave Marshall an IV, and he’s heading home,” Janssen said. “He was fine this morning. Standing around, bummed out that he wasn’t going with us.”

Marshall will return to Anchorage sometime Wednesday, said Janssen’s daughter, Chelsea.

“He’s doing just fine. He’s still at the checkpoint and they’re flying him back home today.”