Elk hoof disease spreads beyond SW Washington

A disease that deforms the hooves of elk is spreading beyond Southwest Washington into the northwest of the state and across the Columbia into Oregon.

OLYMPIA — A disease that has been killing elk in Pacific County and elsewhere in Southwest Washington appears to be spreading to Northwest Washington.

Researchers suspected the condition commonly known as “hoof disease” was spreading to Skagit County after learning that an elk killed in a vehicle collision near Sedro-Woolley had deformed hooves, according to a Jan. 6 press release from the Washington Department of Fish and Wildlife.

Last month, WDFW scientists sent abnormal hooves from that elk, and three others collected in Northwest Washington to Colorado State University for testing. Results were negative for three elk that were harvested by hunters in Whatcom County. However, the Skagit County elk tested positive for “treponeme-associated hoof disease,” the illness that has infected two Roosevelt elk herds in Southwest Washington.

The highly contagious disease causes severe overgrowth and deformity in the hooves of elk. The brittle hooves may split, or fall off. Affected elk may develop ulcers on their feet and are often rendered unable to walk. As a result, their overall health declines. They can have difficulty foraging for food.

All four of the elk tested at CSU were from the North Cascades Herd — also known as the Nooksack Herd — which includes about 1,000 animals in Skagit and Whatcom counties.

“We routinely send disfigured elk hooves from around the state for testing, but this is the first one outside of Southwest Washington that shows evidence of this disease,” WDFW epidemiologist Kristin Mansfield said in the press release.

Mansfield said WDFW will send samples from the animal to testing facilities at Washington State University and the U.S. Department of Agriculture to confirm the initial findings. Test results are expected next month.

Hoof disease first appeared in the Cowlitz River Basin in the late 1990s, and the number of cases increased sharply starting in 2008, according to the WDFW website. Since then, the disease has spread to about 10 counties in Southwest Washington. It affects both the Mount St. Helens herd, which ranges east from Interstate 5 to the Cascade mountains, and the local Willapa Hills herd, which ranges over much of the area west of Interstate 5, between State Route 12 in Grays Harbor County and the Columbia River.

“It’s definitely an epidemic,” Mansfield said in a follow-up email.

In 2009, WDFW began sending hooves and tissue from affected elk to independent labs for analysis. In 2014, researchers finally had enough data to conclude that treponeme bacteria was the culprit.

According to WDFW, the condition closely resembles “digital dermatitis,” a highly infectious livestock disease. It’s a fairly common cause of foot deformities in sheep, goats and cattle that first showed up in the mid-1970s. However, prior to 2014, it had never before been diagnosed in wildlife.

Mansfield said it’s too soon to know whether the condition will spread to other parts of the state. But there is already some evidence that hoof disease is spreading. In 2015, five elk from Northwest Oregon also tested positive for treponeme, according to WDFW.

Some Washington citizens and groups have harshly criticized WDFW’s response to hoof disease, saying the agency waited too long to get involved and then moved too slowly.

Starting around 2012, the agency ramped up efforts to study the disease and slow its spread. These efforts include policy changes — hunters are now required to leave hooves at the harvest site, and WDFW has developed a somewhat controversial protocol for euthanizing animals that are suffering as a result of the disease — as well as public meetings, studies and collaborations with veterinarians, universities, other agencies, and volunteers and sportsmen.

According to the website, a team of 223 volunteers in spring 2015 “... drove more than 7,000 miles across 10 counties to help assess the proportion of elk affected by the disease.” Participants documented observations of more than 280 groups of elk.

As of January 2016, wildlife managers had radio-collared more than 90 cow elk in the Mount St. Helens area. They plan to monitor the cows’ welfare over the next four years. Additionally, citizens can now report sightings of limping or dead elk through a hotline and website. WDFW staff investigate those reports and submit potentially diseased hooves for testing.

Researchers are making real progress, but there is still much to learn, WDFW “hoof disease coordinator” and biologist Brooke George said on Jan. 8.

“We don’t know how it starts, meaning, how does the hoof become susceptible to this bacteria? There are many potential causal factors,” George said.

Current efforts focus on determining “where it is and where it isn’t,” according to George, and on learning more about how it affects elk survival and reproduction.

According to a report about the 2015 “citizen science” study, about 40 to 60 percent of the elk groups in the Willapa Hills herd included at least one limping elk. The disease is less prevalent in western Pacific County, but it’s definitely there — a WDFW map of limping or dead elk sightings shows at least 30 reports in the county. Since not all cases get reported, the actual number of affected elk may be higher.

George said that study was useful, but scientists need a much bigger sample size, and more reliable data. Documenting hoof disease can be challenging, because most studies rely on observations of dead or limping elk. That means most of the data comes from public land that is fairly easy to access. Though landowners are increasingly granting access to researchers, data from private properties isn’t as complete. Another challenge is that observers’ accuracy rates can vary significantly, depending on a variety of factors.

Additionally, elk are “very tough animals,” George said, and may be sick for a long time before they show any obvious signs of illness.

“We’re having a very hard time detecting the disease at earlier stages,” George explained. “We are catching the most severe animals, but when you’re seeing a group of elk running away and you’re trying to observe them, you’re probably not catching ones that have early lesions.”

According to George, WDFW staff hope are devising ways to overcome some of the obstacles they encountered during the 2015 study. One possible new approach would involve having volunteer hunters would evaluate hooves, and report their findings.

George said her agency will hold off on planning additional “citizen science efforts” until staff have determined which areas they need to study most urgently, and how to use the volunteers most effectively.

To report elk with hoof deformities or learn more about hoof disease in elk, see WDFW’s website at wdfw.wa.gov/conservation/health/hoof_disease/.

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