Pneumonia outbreak detected in Reynolds Creek bighorn sheep in Southwest Idaho

A pneumonia outbreak caused by the bacterium Mycoplasma ovipneumoniae (M.ovi) was detected in the small herd of approximately 30 California bighorn sheep in Reynolds Creek, Unit 40, during routine disease surveillance in mid-December. 

The bighorns in Reynolds Creek are one of several herds of California bighorn sheep in the Owyhees. While these herds are relatively isolated, some intermingling occurs among them, posing a substantial disease risk to the overall population. 

M.ovi outbreaks often have population-level effects on bighorn sheep. It’s common for about half of the infected herd to die. Fish and Game staff are gathering information on the current outbreak and evaluating options to prevent further spread to neighboring herds where M.ovi has not been detected. 

Fish and Game staff tested bighorn sheep for M.ovi in several neighboring herds as part of their routine disease monitoring, and all samples came back negative. 

“At this point, we know we have M.ovi in Reynolds Creek and that it has not been detected in neighboring bands in the Big Jack’s Creek, Little Jack’s Creek, Castle Creek, and Owyhee River drainages,” said Regional Supervisor Josh Royse. “We are exploring all options to ensure that remains the case.” 

IDFG asks people to call the Southwest Region Office at 208-465-8465 to report any sick or dead bighorn sheep in the areas south of the Snake River and west of Highway 51.