PINEDALE, Wyo. — Since mid-February, the Wyoming Game and Fish Department (WGFD) has reported that around 200 pronghorn have died from a rare disease outbreak south of Pinedale near the southern end of the Mesa.
WGFD and Wyoming State Veterinary Laboratory (WSVL) are collaborating to investigate the outbreak that preliminary lab results are identifying as Mycoplasma bovis.
Mycoplasma bovis, not to be confused with Mycobacterium bovis that causes tuberculosis in cattle, is a known disease in cattle and bison and has occasionally been seen in deer. Mycoplasma bovis causes severe pneumonia in pronghorn, which leads to a high mortality rate.
The first Mycoplasma bovis outbreak in pronghorn was seen in Gillette, Wyo., in the winter of 2019/2020 and involved at least 460 animals.
“We were hoping that the outbreak in Gillette was an isolated thing, but now to see it come back in a different location is concerning,” says Hank Edwards, wildlife disease specialist with WGFD.
According to Edwards, there was no evident increased risk for the pronghorn population this winter, although harsh winter conditions could have weakened the animals as they fought the weather.
Jackson Hole typically sees a large pronghorn population that moves south in the winter and back up in the spring. There is currently no prediction for the duration and the geographic distribution of this particular outbreak, although a WGFD press release has stated that no other wildlife populations in Wyoming have currently seen significant mortality associated with the disease.
“I think it may not be until the snow melts before we can really get out there and determine the extent of it,” Edwards says. “It may not be until the outbreak is over.”
There is currently no evidence that Mycoplasma bovis infects humans or affects domestic pets such as horses, dogs or cats.
This news comes after WGFD released a report that estimates an above average winter mortality rate for pronghorn this season.
