Sure, guard dogs are cool, but now they’re going to have to share top billing with guard cats. An animal group in Chicago has recruited a thousand feral cats to help protect the Windy City against a growing rodent invasion. The feisty felines are part of the Tree House Humane Society's Cats at Work program, which takes strays, spays or neuters them, and then releases them to do their stuff. Just in time, too. Chicago was recently named “America’s rattiest city” by Orkin pest control. (WGN)