Rare Disease Causing Pronghorn Deaths Near Gillette

Mar 18, 2020

Credit Wyoming Game and Fish Department

Approximately 75 pronghorn have died in a 35 square mile area north of Gillette this year. The Wyoming Game and Fish Department has identified the cause: a bacteria called Mycoplasma bovis, which is usually found in cattle and has not been known to affect pronghorn.

Game and Fish Wildlife Disease Specialist Terry Creekmore said they don't know why this is occurring.

"This began kind of unexpectedly last year north of Gillette, slightly different location than this year. Pronghorn began dying in the middle of February or so," he said.

Creekmore said they are unsure when the die-off will stop.

"Last year mortalities stopped about the first of April, and possibly that'll happen this year. But weather conditions were different last year than this year, and we just don't know enough about this disease to know what's going to happen," he added.

Though this year, the area where pronghorn are dying is about 10 miles from last year's area, he said.

Creekmore said the disease does not affect horses, cats or dogs. Though across the country, there are limited cases of other animals besides cattle dying from the bacteria. Game and Fish found a mule deer near Wheatland and a whitetail deer near Sheridan that tested positive for Mycoplasma bovis a couple of years ago.

The department is working with the Wyoming State Veterinary Laboratory to study the disease, Creekmore said.

Game and Fish is now asking for residents' help. Residents who spot sick or dead pronghorn should call their local game warden or the Sheridan regional office. Creekmore said while this is currently only happening north of Gillette's airport, Game and Fish is interested if the mortalities are occurring outside of the documented area.

Creekmore said residents should call in if they find a sick or dead pronghorn away from highways or in another unusual location.

"If you see sick animals that are lethargic or separate from the herd, maybe they even have their head down on the ground...they may very well be ill," he said.

This bacteria affecting pronghorn should not be confused with Mycobacterium bovis, which is known to cause tuberculosis in cattle.

Have a question about this story? Contact the reporter, Catherine Wheeler, at cwheel11@uwyo.edu.