Pneumonia in Bighorn Sheep: Background

Bighorn sheep pneumonia is one of the most concerning diseases that affects our bighorn sheep populations. It’s primarily caused by Mycoplasma ovipneumoniae, and wild bighorn sheep contract this disease through direct contact with domestic livestock.

The amount of infection can vary within a herd and cause mortality in more than 90% of the infected animals. Animals that do not die may become carriers, putting naïve lambs at risk. In these cases, the number of lambs that reach adulthood is reduced such that the overall herd size declines for several years. Several states have reported severe losses in bighorn sheep populations with the disease.