Bighorn sheep are very susceptible to bacterial infections which cause pneumonia.  Six states (Idaho, Nevada, Montana, Utah, Washington, Wyoming) have had severe losses in their bighorn sheep this year (2010).  The amount of infection in any one herd varies; as many as 90% of the animals can be affected and in some cases all of the affected animals will die.  Those that don’t die may be affected by the disease for a year or more and may become carriers.  In cases where herds have survived, the number of lambs that survive to adulthood is reduced such that the overall herd population actually declines for several years.  While contact between domestic sheep and goats has preceded some outbreaks of pneumonia in bighorns, such contact has not been confirmed in all cases.

• Manheimia hemolytica (previously Pasteurella) and Mycoplasma ovipneumoniae have been isolated from sick bighorn sheep.
• Bighorn sheep are more susceptible than domestic sheep to infection by these organisms.
• Many domestic and wildlife species carry these and related bacteria.
• People cannot contract pneumonia from bighorn sheep.
• There is no effective treatment or vaccination for bighorn sheep.

The Arizona Game and Fish Department considers this disease to be a serious potential threat to the bighorn sheep herds of this state and the Department monitors the herds for the occurrence of it.  The public can assist the Department in its efforts by reporting sick bighorn sheep to either the Wildlife Health Specialist or the appropriate regional office.  In addition, AGFD works with ranchers and National Forest managers to minimize contact between domestic livestock and bighorn sheep.

For more information contact:

Anne Justice-Allen, Wildlife Health Specialist
Arizona Game and Fish Department
5000 W. Carefree Highway, Phoenix, AZ 85086-5000
Phone: (623) 236-7351      E-mail: ajustice-allen@azgfd.gov