GUNNISON, Colo. (AP) -- Eight bighorn sheep have died east of Gunnison, and wildlife officers say all showed signs of pneumonia.

The Division of Wildlife says seven were found dead and the eighth was so sick it had to be euthanized. All died in the last week of December.

Officials say tests showed pneumonia is the likely cause of death for at least some of them. Further tests are planned.

J Wenum, the division's Gunnison area manager, says bighorns are susceptible to pneumonia and treatment options are limited.

He says the eight were part of a herd of only 50, and the deaths are a significant loss.

Wenum says the surviving animals are being monitored closely.

The Rocky Mountain bighorn sheep is the state animal.