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Elk hoof disease

A mysterious and crippling disease has made its way to Washington’s Blue Mountains.

On Jan. 17 a hunter shot a cow elk in the Pikes Peak area of the Blue Mountains in Walla Walla County. The hunter noticed that the hooves of the animal were deformed. So he submitted the hooves to the Washington Department of Fish and Wildlife.

Since then the Washington State University animal disease diagnostic lab confirmed that the elk had the infectious disease known as treponeme-associated hoof disease. Or, more commonly, elk hoof disease.

“This detection is the farthest east we’ve documented hoof disease in Washington,” said Kyle Garrison, WDFW’s statewide hoof disease coordinator.

The disease has been documented in some elk killed in the Oregon part of the Blue Mountains, he said. And in February the disease was confirmed in Idaho near White Bird. In April, WDFW confirmed the disease for the first time east of the Cascades.

“It’s certainly something we should all be concerned about,” he said. “It’s a disease that is very difficult to manage and we don’t know what the future holds for the disease’s manifestation in the Blues.”

The disease is most common in southwestern Washington, particularly the Willapa Hills and Mount St. Helens herds.

The poorly understood disease, which resembles hoof diseases that occur in domestic livestock, originated in Washington and has since spread to Oregon and Idaho.

Limping elk and elk with hoof deformities were first documented in Washington in the early 2000s with sightings greatly increasing around 2008, Garrison said. However, the disease wasn’t formally diagnosed until 2014 after five years of analysis by five independent laboratories. While relatively common in livestock, hoof disease caused by treponeme bacteria had not previously been diagnosed in wildlife.

In 2018, the Legislature allocated $3 million to WSU for two years of work on elk hoof disease.

The disease’s full impact on elk populations is not yet known.

Nor is its origin, said Margaret Wild, the head of WSU’s elk hoof disease research efforts. Prior to coming to WSU in June, Wild worked as the chief wildlife veterinarian for the National Park Service. While there she worked extensively on chronic wasting disease research. In fact, she draws some parallels between CWD and elk hoof disease: both of which started as relatively isolated and unknown diseases.

“There is a lot of speculation that goes along with this disease,” Wild said.

A study of the Mount St. Helens herd started in 2015. Garrison said WDFW hopes to have the study’s findings published in a year.

But according to preliminary findings, the disease greatly reduced the herd’s survival rates, overall body condition and reproduction, Garrison said.

However, the diseases’ exact impact on elk mortality isn’t clear. Garrison pointed out that the Mount St. Helens herd was already nutritionally challenged and not known for great health.

Over the past five years, the Mount St. Helens’ herd has declined 35 percent. But during that same time, the state had hunters harvest more than 1,000 cow elk in an effort to bring the herd into balance with habitat capacity.

“You know, like a lot of research, its hard to extrapolate,” he said.

In 2015, volunteers surveyed southwestern Washington elk herds. They found at least one limping elk in 48 percent of all elk groups surveyed. A spring 2017 aerial survey of the same area found limpers in 28 percent of all elk groups.

And a 2016 survey of Western Washington elk hunters found that 15 percent harvested elk with deformed hooves. In 2017, In the Willapa Hills 10 percent harvested elk with deformed hooves and in the Mount St. Helens’ area 17 percent did, Garrison said.

The 2018 numbers are not yet available. WDFW is now asking all Washington hunters, Garrison said.

In Western Washington annual survival rates have ranged from 58 to 68 percent for radio-collared elk with hoof disease as compared with 67 to 79 percent for non-disease elk.

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And while the disease has been documented in northwest Washington, it hasn’t expanded in the same way it has in the southwest.

Next week WDFW will start its annual population survey in the Blue Mountains. Garrison hopes that survey will provide more information about prevalence in the Blues.

“We don’t get the feeling that there are a lot of other sick elk out there,” he said.

Last week, WSU took the first step in building a 4-acre enclosure that will allow them to study the disease in captive animals, Wild said. A key question researchers will ask is how the environment impacts prevalence and severity. There is some thought that damper climates help spread the bacterial infection.

“I think once we start doing the work in the captive elk we will be able to tell what environmental factors are important in the occurrence of the disease,” Wild said.

The pen will be located in Pullman.

Wild hopes it’s completed and research started by this time next year. Pinpointing exactly what factors affect the spread and severity of the disease is nearly impossible in the wild, she said.

“It’s just so hard to identify it in the wild where you have so many variables occurring at the same time,” she said.

At this point even if a treatment were found, it would be difficult to deliver to free-roaming elk.

“It is so hard to manage a disease in a wild animal and free-ranging animal,” Garrison said.

Wild and Garrison both stressed the importance of hunters and others keeping an eye out for limping elk or deformed hoofs.

“I think it’s important to know where disease are occurring for a number of reasons,” Wild said. “Once it’s established in an area it becomes much more challenging to manage.”

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