Fatal to whitetails, EHD can affect testosterone levels in mule deer bucks

Dec. 17—BISMARCK — Mule deer are less susceptible to a midge-borne illness that is fatal to white-tailed deer, but epizootic hemorrhagic disease can still potentially affect males of the species, a Game and Fish Department biologist says.

There is evidence that EHD affects testosterone levels of mule deer bucks that are exposed to the disease, said Brent Weston, wildlife health biologist for Game and Fish in Bismarck.

Hunters in western North Dakota and other parts of the West have reported shooting mule deer bucks with antlers still in velvet late in the fall, Weston said; in other cases, bucks have missing or shrunken testicles.

Bucks in North Dakota typically lose the velvet on their antlers in September.

While the Game and Fish Department isn't specifically studying EHD's impact on mule deer bucks, Weston says he's read scientific papers about the phenomenon.

"They're still looking to find out the exact mechanism behind it," he said.

The department received more reports of affected mule deer bucks last year than they've gotten this year, Weston said. A massive EHD outbreak occurred last year along the Missouri River and farther west in North Dakota.

According to the Game and Fish website, EHD "causes dehydration and a high body temperature, causing deer to seek water before they die. Other clinical and behavior symptoms may include respiratory distress; swelling of head, neck, and tongue; lesions on tongue and roof of mouth; indifference to humans; and in later stages, hemorrhaging from body orifices."

For the first time, EHD last year also

killed numerous whitetails in localized areas of the northern Red River Valley.

Widespread drought and the abundance of exposed organic material left by receding water created ideal breeding conditions for the midges that transmit EHD.

EHD isn't a danger to humans, but hunters shouldn't shoot or consume a deer that appears sick, Game and Fish advises. Dead deer observations should be reported to Game and Fish at gf.nd.gov or by calling (701) 328-6351.

The Game and Fish Department is awaiting lab results from hunter-harvested deer it sampled for chronic wasting disease during the gun season, but a deer shot during bow season in the northern part of Unit 4B in far western North Dakota has been confirmed as positive, Weston said.

That's the only confirmed positive case to this point, he said; additional results are expected soon.

"We still have quite a few results coming in and being confirmed, so there's likely to be quite a few more," Weston said.

Game and Fish focused this year's sampling efforts on units 1, 2B, 3A1, 3A2, 3A3, 3A4, 3B1, 3B2, 3C, 3D1, 3D2, 3E1, 3E2, 3F1, 3F2, 4A, 4B, 4C, 4D, 4E and 4F. The department added 2B in the Red River Valley to the sampling list after a single whitetail buck shot in the fall of 2021 near Climax, Minn., tested positive for the disease that is fatal to deer, elk and moose.

The hunter who shot the buck voluntarily had it tested, and it remains the only deer on either side of the Red River to have tested positive for CWD in the Red River Valley. Game and Fish establishes a surveillance unit within 25 miles of any positive case, even if it's in a neighboring state or province.

Statewide, the department sampled about 2,000 deer heads for CWD this fall, Weston said, a number that could grow as self-sampling kits available for the first time this year trickle in.

"We're pretty much done with the heavy lifting," he said. Few hunters in 2B turned in samples for testing.

"It's unfortunate that we don't seem to have gotten many samples from 2B this year," Weston said. "Maybe more will come in, we'll have to see."

As part of the department's

new CWD management plan that takes effect in 2023,

the goal is to sample 10% of the deer in a unit that is scheduled for hunter-harvested surveillance. So, if 300 licenses were available in a particular unit, Weston says, the goal would be to sample 30 deer.

"That would be ideal," he said. "Right now, we're not really getting close to that."

Before the recent positive case in 4B, there had been 70 confirmed cases of CWD in North Dakota since 2009, when the disease first was found in Unit 3F2 in the southwest part of the state.