Pneumonia outbreak detected in Washington bighorn sheep population

The Washington Department of Fish and Wildlife says it detected pneumonia in the Northern Hells Canyon bighorn sheep population in December of 2023.

Bighorn pneumonia is caused by a bacteria that can kill sheep populations while reducing lamb survival rates for many years after the initial outbreak. There is no current treatment or vaccine.

Officials have confirmed cases in Washington, Idaho, and Oregon.

The Idaho Department of Fish and Game is working with the Oregon Department of Fish and Wildlife to monitor the outbreak.

“It will take some time before we know the magnitude of this outbreak,” said section manager Kyle Garrison. “Biologists in all three states are in the field working to get a better understanding of the impacts.”

To report a dead or sick bighorn sheep use the WDFW’s reporting tool.