It was a python.
Betty Corey says at first she thought one of her dogs was making the hissing noise.
She called 911 and a county animal control officer responded.
Officer Brian Boman says the agency will keep the snake at its shelter, in case the owner comes looking for it.
Boman figures the snake is someone's escaped pet.
Corey says the 4-foot-long ball python probably got into her home through the doggie door.