We had a dog chew through a phone cord as my mothe was talking on the phone. Phones don't carry enough voltage to do any harm, so it isn't a terminal action. Chewing through a power cord may or may not be. 110 current will pack a heck of a punch, and getting it through the mouth would probably be pretty bad, but the result largely depends on whether the mouth clamped shut or open, and how quickly the breakers blew.