Pneumonia Outbreaks Hitting Northwest’s Wild Bighorn Sheep

May 28, 2014

Bighorn sheep in the Northwest have their lambs in early spring. About now, those babies start playing together in the mountains — a sort of lamb daycare.

But that sweet, social behavior is spreading a deadly disease in several herds throughout the region.

Just as lambs get a bit more adventurous and start to socialize, they are at greater risk for infection. In this case, it’s strains of very contagious bacterial pneumonia. The respiratory disease is common in domestic sheep and goats, but doesn’t usually kill those animals.

However, in the bighorn sheep, it's often deadly. Generally, the problem is adult bighorns can wander great distances and mingle with domestic animals. Then they bring the infection back to their wild herd. It hits the lambs the hardest.

Rich Harris, a manager of bighorns for Washington State Fish and Wildlife, said, “It’s tough when the disease comes from something that has to do with humans’ impact on the land.”

Dozens of lambs have been lost in the Northwest so far this spring, especially near Yakima and Hells Canyon that spans Washington, Oregon and Idaho. Washington State University is helping to research the disease and its causes, but as of now, there is no solution.