Highly pathogenic avian influenza, commonly called bird flu, has increasingly spread to mammals and infected hundreds of people, raising concerns that it may lead to human-to-human transmission and turn into a new pandemic.

The detection of bird flu in a sheep is another sign that the H5N1 virus is adapting to hop to new hosts

Nearly a dozen domestic cats in Colorado have gotten the most recent strain of bird flu and officials say only one of the 11 cats survived. That includes indoor-only and indoor-outdoor cats.