Hunters key to study of elk hoof disease

If the trend continues, 95 percent of South Cascade hunters will be coming home tonight to tell the stories about the big sets of branch antlers that got away during this year's Roosevelt bull elk hunt.

Julia Burco wants to hear about the bulls and cows hunters saw limp away.

Burco is an Oregon Department of Fish and Wildlife veterinarian who is trying to get a handle on the slowly growing hoof disease infecting pockets of Roosevelt elk largely in northwest Oregon and Rocky Mountain elk in far northeast Oregon.

It's worked its way south into Oregon from southwest Washington, and the bacteria that causes this crippling and painful disease could already be here.  

"It could pop up any time," Burco says. "The good, and bad, thing about this disease is it's quite visible."

Since it was first discovered in Washington County in 2014, 17 confirmed cases have come across Burco's desk, plus a spate of suspected cases, including one unconfirmed report in western Douglas County.

In all but the Douglas County case, the infected animals were discovered by hunters, Burco says. So it's hunters who can help Burco and other scientists determine the depth of the bacteria, how it's spreading and how best to cut it off.

"We're trying to get a handle on distribution and a better understanding of what factors are similar in these areas," Burco says. "Is there an underlying cause that ties them together?"

Hoof disease popped up in southwest Washington elk in the late 1990s, but it wasn't until 2014 that treponeme bacteria was confirmed to play a role in the deep-tissue destruction that leads to deformed, overgrown or broken hooves.

It does not affect humans, and the meat from diseased animals is fine, according to ODFW.

It plays no favorites, hitting both sexes and all age classes of elk. The bacteria is believed to be spread in damp, moist soils by elk and domesticated sheep and cows, and despite rumors it has not been linked to herbicide treatments by private timber companies, says Michelle Dennehy, ODFW's Wildlife Division spokeswoman.

Unlike the deadly adenovirus that has plagued black-tailed deer in Southern Oregon for years, hoof disease doesn't necessarily kill elk. They can live several years and even reproduce with what is sometimes called "slipper hooves."

Hooves are lab-tested for the presence of the microorganisms. Diagnosis is not quick, with a three-month turnaround in the Iowa lab that does the testing, Burco says.

ODFW biologist Vince Oredson says the agency's Central Point office has yet to receive a report of hoof disease.

"Hunters are pretty savvy about what's going on out there," Oredson says. "And we have landowners watching elk all the time, and they haven't reported it."

One of the theories is that the bacteria has been around for a long time and that environmental factors such as flooding may have stirred it up and moved it around, Burco says.

That's similar to the adenovirus, which wasn't detected until the 1990s here, but most scientists studying it believe it was misdiagnosed as blue tongue before that.

"It's certainly here but it's not spreading as fast here as it did in Washington," Burco says.

But it's spreading strangely, she says. Seeing it in northwest Oregon was a gimme because of its proximity to southwest Washington, Burco says. But seeing it pop up last year in Eastern Oregon was odd, because Roosevelt elk don't migrate that far east, and Rocky Mountain elk don't summer near the coast.

"The biggest change in the past year is that we've seen it in places I didn't expect," Burco says.

That next unexpected case could be in Southern Oregon. If it is, chances are it will come from a hunter whose quarry didn't get away in part because of its painful limp.

"Almost all the hooves we're getting are from hunter harvest," Burco says.

— Reach Mail Tribune reporter Mark Freeman at 541-776-4470 or mfreeman@mailtribune.com. Follow him on Twitter at www.twitter.com/MTwriterFreeman.

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