Elk hoof disease has been found for the first time in the Yakima herd in Central Washington, expanding the geographic reach of a pathogen that resembles one that makes cattle lame.
The Washington State University College of Veterinary Medicine confirmed the disease in a juvenile elk captured in February at a feeding site near Ellensburg in Kittitas County, the state Department of Fish and Wildlife said Monday.
The bacteria has now been found in eight of the state's 10 elk herds, as well as in Oregon, Idaho and most recently in California.
The deformities caused by elk hoof disease are associated with treponeme bacteria, known to cause digital dermatitis in cattle, sheep and goats, according to Fish and Wildlife.
Scientists suspect the disease spreads as elk step in the treponeme bacteria left in the ground by infected elk.
Whether livestock can pick up the disease from elk is the "million-dollar question," Fish and Wildlife ungulate specialist Kyle Garrison said.
"It's an important question. One we don't have a good answer to," he said.
The disease appeared in the early 2000s in elk around Mount St. Helens in southwest Washington. The prevalence of the disease increased dramatically in 2008 after a massive flood drowned hundreds of cattle in Lewis County.
Scientists, including from WSU and Fish and Wildlife, speculate that the flood may have created conditions for a new digital dermatitis-like disease, according to a 2019 paper in the journal Veterinary Pathology.
The disease is much more common in damp Western Washington, but has now been found in three Washington counties east of the Cascades. It was found in 2018 in Klickitat County and in 2019 in Walla Walla County.
"That challenges the notion that moist conditions are a requisite for the disease to occur," Garrison said. "Maybe moisture is important, but not as important as we previously thought."
The diseased elk from the Yakima herd was one of about a dozen captured and tested. The others were not infected.
The disease was in an early stage, and the animal wasn't limping. The department has not been receiving reports of elk limping in the herd, Garrison said.
The disease remains rare in Central and Eastern Washington. While 12% of the elk harvested in Western Washington last year were believed to be infected, less than 1% were infected east of the Cascades, according to Fish and Wildlife.
The California Department of Fish and Wildlife reported the state's first cases of elk hoof disease on May 7. WSU confirmed the bacteria in two elk in Del Norte County, which borders southwest Oregon.
The disease had previously been detected in Lane and Douglas counties in Southern Oregon, but not all the way to the California border, according to the Oregon Department of Fish and Wildlife.
Researchers are trying to understand how the disease is spreading geographically, Garrison said. "Are we seeing independent outbreaks of this disease? We don't have good answers to that," Garrison said.
Idaho Fish and Game confirmed the state's first case in early 2019. The elk had been harvested by a hunter near White Bird in north-central Idaho.
Elk hoof disease has not been found in the Colockum herd in Central Washington or the Selkirk herd in northeastern Washington.