Pets also can be exposed to avian influenza directly through an infected bird, specifically animals such as cats or dogs that hunt and then eat an infected bird, Davis warned. Ferret owners also should take caution to keep their pets safe. "We recognize that ferrets are likely to be highly susceptible," she added.

Federal health officials say the U.S. has the building blocks to make a vaccine to protect humans from bird flu, if needed. But experts warn we're nowhere near prepared for another pandemic.

A wave of bird flu has devastated poultry populations and spread to dairy cows in the US and led to a number of other animals' deaths, raising fears of widespread human transmission.

Federal testing and surveillance of the outbreak has so far lagged since initial detection in dairy cows more than a month ago.