Disease Outbreak Affects Wyoming’s Bighorn Sheep

The Wyoming Game and Fish Department discovered a disease outbreak in the Devil's Canyon bighorn sheep herd northeast of Lovell, according to a news release on their site.

A landowner reported the dieoff in addition to a mortality signal from a GPS collared bighorn sheep in the herd.

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“Since Oct. 14, Game and Fish has documented 37 bighorn sheep mortalities in the Devil’s Canyon herd, which constitutes approximately 10 percent of the population,” said Corey Class, wildlife management coordinator for the Cody Region. “The majority of deaths have occurred in ewes and lambs.”

“We have been working closely with a local landowner who has been key to managing and monitoring this disease outbreak,” Class said. “We greatly appreciate their assistance and cooperation.”

Game and Fish collected biological samples from nasal and tonsil swabs from bighorn carcasses at the reported site on October 16th.

The samples were sent to the Game and Fish Wildlife Health Laboratory in Laramie for analysis where a pathogenic strain of the bacteria Mannheimia haemolytica was cultured, according to the news release. This strain type is known to cause lethal pneumonia in sheep. The source of the infection is unknown.

Currently, 24 bighorn sheep in this herd are fitted with GPS tracking collars to monitor the population and spread of disease.

“The collars will now help us monitor bighorn sheep populations from a disease perspective and document additional mortalities,” Class said.

The bighorn sheep carcasses are being disposed of to decrease spread of the disease, said the news release.

“Our limited experience with this pathogen gives us some hope the outbreak will run its course quickly, with minimal mortalities,” said Hank Edwards, Wildlife Health Laboratory supervisor.

The Devil's Canyon bighorn sheep herd (Hunt Area 12) is located in the northwest portion of the Bighorn Mountains. This population is estimated at 250-300 individuals.