Yukon wildlife officials say they're watching closely for any signs that a disease-causing bacteria poses a threat to local populations of caribou or mountain sheep.
They're concerned about Mycoplasma ovipneumoniae (M. ovi), a respiratory bacterium that can cause disease in some animals.
Last month, a caribou from the Fortymile herd was found dead in Alaska from bronchopneumonia. A necropsy determined that the animal tested positive for M. ovi.
"We don't want to make too much of it, but we certainly take it seriously," said Mary VanderKop, Yukon's chief veterinary officer.
"It's quite an unusual circumstance," VanderKop said. "The finding of it in a caribou is kind of surprising."
The bacteria has also been found in healthy moose, Dall sheep and mountain goats in Alaska.
Possible risk to sheep
Vanderkop said the dead caribou is also a concern because the Fortymile herd's range stretches into Yukon and overlaps with the range of sheep. The fear is that a deadly infection may spread.
"We've been looking for it in the Yukon for a while, because of the concern that it might cause infection and pneumonia in thinhorn [Dall] sheep, as well as bighorns," Vanderkop said.
"It's possible that the strain that caribou might be carrying could be a health risk to sheep," she said.
The Yukon government plans to expand surveillance and testing of Yukon caribou, to watch for M. ovi. Hunters are also being encouraged to use sampling kits (provided by the government), to swab the noses of animals they harvest.
Vanderkop said the bacteria can be passed from animal to animal, usually by "direct nose-to-nose contact."
She admits that caribou and sheep don't often mingle closely, but it's not impossible.
"I wouldn't rule anything out, when it comes to wildlife. If there's one thing about wildlife, it's that they're unpredictable, in my experience," Vanderkop said.