A dog named Firefly died shortly before reaching the halfway point of the 2017 Yukon Quest International Sled Dog Race.

The dog arrived with musher Yuka Honda at the Dawson City checkpoint just before 4 a.m. on Thursday.

Race Marshal Fabian Schmitz: "We'll find out what happened here." (Cheryl Kawaja/CBC)

Race marshal Fabian Schmitz said Honda told officials when she arrived that she had a dead dog in her sled bag.

"We'll find out what happened here," he said, adding "it's a sad thing, it's tough, it's really tough."

An emotional Honda spoke with CBC reporter Cheryl Kawaja, who's in Dawson City.

"He was very friendly, he loved to eat. He's a happy dog," she said.

Yukon Quest musher Yuka Honda talks about her dog Firefly, she says he died just outside Dawson City. <a href="https://twitter.com/hashtag/YQ2017?src=hash">#YQ2017</a> <a href="https://t.co/6bORiHELtO">pic.twitter.com/6bORiHELtO</a> —@CherylKawaja

Honda said the dog died shortly before she reached Dawson.

The race's head veterinarian, Dr. Cristina Hansen, said a necropsy was done Thursday morning. Preliminary results revealed the dog had an enlarged heart and had ingested several booties. A full report will be released in about two or three weeks.

2nd dog to die in 10 years

All racers are required to stop for 36 hours in Dawson City. Schmitz said he'll ask Honda if she intends to complete the race after she has a rest.

This is the second time one of Honda's dogs has died in the Yukon Quest.

In 2007, a dog named Jewel choked to death.

Officials said at the time Honda lost her 14-dog team after getting off the sled to untangle her leaders from the two dogs behind them. They pulled the two snowhooks she had set as brakes and took off before she could catch the sled.

Musher Brent Sass picked Honda up as she was chasing her team down the trail, but by the time they caught up with the dogs, Jewel was dead.