The two dogs that died in the Tustumena 200 over the weekend died of the same thing but had little else in common at the time of their deaths, the race's veterinarian said Tuesday.
Gary Kuchinka of Soldotna's Twin Cities Veterinary Clinic said both dogs died from pulmonary edema, or fluid in the lungs.
Neither animal -- 2-year-old Fox, a female on Paul Gebhardt's team, and 3-year-old Jack, a male on Nicolas Petit's team -- showed signs of injury or other trauma, including abuse, Kuchinka said. Both mushers have been cleared of any misconduct.
Kuchinka, who has also served as a vet at the Iditarod and Yukon Quest, said he sent tissue from both dogs to a pathologist to see if tests can determine what caused the edema.
"You usually don't see that scenario with a 200-mile race," he said.
It was a warm weekend on the Kenai Peninsula, with temperatures in the 30s. Most mushers prefer running their teams in lower temperatures, because warm weather can be taxing on a dog team.
"The first thing that everybody says about this race is that it was warm," Kuchinka said. "But what do you say when 498 of them make it, and two of them don't?
"We know that with a black dog or a heavy-coated dog, we really watch them (for signs of overheating), but these two didn't fit that mold."
Neither dog had a heavy coat of fur and both were light in color, he said.
Beyond that, the animals died in contrasting race circumstances.
"The two dogs were in different scenarios -- one was racing during day, one ran overnight; one happened near the end of run, one happened after a very long rest period. So that stuff didn't correlate."
Petit was running his team at night. He had already reached Homer, the halfway point of the race, and was about 30 miles into the 50-mile run to Freddie's Roadhouse on Saturday when Jack died.
Gebhardt had just completed a layover of about five hours at Freddie's and had started the final 50-mile run to the Kasilof finish line Sunday when Fox died. He arrived at the finish line in fourth place, with Fox in his basket.
Both dogs passed vet checks before and during the race, Kuchinka said.
"They did all right in the pre-race vet check and they were OK coming out of their last checkpoint," he said. "In fact they were two of the more energetic and better-looking dogs in the teams."
The pulmonary edema caused hypoxia, or a shortage of oxygen, in both dogs. Infections, accidents and changes in protein are among the triggers of edema; Kuchinka said he hopes pathology tests may show what caused each dog's condition.
He said Gebhardt and Petit both said the dogs deteriorated rapidly.
"It can be sudden, and they said it was very sudden," he said. "They both tried CPR and it was ineffective."
Tami Murray, race director of the Tustumena 200, said Jack and Fox are the first dogs to die in the race. "(We) take great strides to protect the dogs and the mushers," she said.
Race rules require that mushers take 10 hours of rest during the race, including a mandatory four-hour layover at Freddie's on the return trip from Homer.
Mitch Seavey, the winner of this year's race, recorded a time of 30 hours, 7 minutes. In accordance with race rules, Seavey and his team would have spent one-third of that time resting.
Reach Beth Bragg at email@example.com or 257-4335.