By Jessianne Wright EBS Contributor

GARDINER – A common viral disease in domestic sheep and goats is the suspected cause of scabby sores around the mouths of bighorn sheep in Yellowstone.

Known as contagious ecthyma, or sore mouth disease, this illness is widespread in wild bighorn sheep populations within the Rocky Mountains from Alaska to California, however park spokeswoman Vicki Regula said this is the first time sore mouth has been observed in Yellowstone.

Sore mouth disease is caused by parapoxvirus and is transmittable to people if direct contact occurs. The illness is typically spread from ewes to lambs, and affected animals usually recover without scarring. The scabby sores often disappear in two to four weeks.

In severe outbreaks, however, deaths may occur when the sores limit an animal’s ability to eat. This tends to have the greatest impact on lambs that refuse to nurse because of the sore mouths.
As of EBS press time Dec. 20, only breeding age rams have been observed with the lesions, after the park’s videographer noticed some rams between Mammoth Hot Springs and Gardiner with mouth sores on Nov. 21.

Park officials reported in a news release that the cause of this recent outbreak is unknown, but its impact on rams is likely the result of frequent contact with each other and possibly infected ewes during the breeding season.

Wildlife biologist Karen Loveless, who is based in Gardiner, said she has received several reports of sheep with the disease north of the park near Cinnabar Mountain and Tom Miner Basin.

“I suspect they’re the same three rams, moving because of the rut,” she said. Loveless confirmed one sighting of a diseased bighorn outside of Yellowstone, having spotted a ewe with lesions on her mouth. “She was eating and did not look skinny,” Loveless said.

Officials report that the disease is difficult to control in bighorn sheep. Often, control efforts are not warranted since animals build up protective antibodies and are usually able to recover from the disease.

Biologists continue to monitor the infected animals and herd, both within Yellowstone and near Gardiner.