Hey Chris, Rocky hardly ever barks unless he thinks he hears someone knocking on the door, and then Rambo never hushes up, I even think he barks in his sleep. I mean if its to hot in the house for his liking he barks, if he's hungry he barks, if he doesn't like something he barks, if he wants attention he barks, if he sees a fly flying he barks, I take him outside, and he goes bananas barking, Morale of the story, some bark a lot, Rambo, some bark very little Rocky. Usually if I hold or play with one of Rockys toys, and he gets jealous of me and his toy, I can entice him to bark, if i knock on my coffee table like someone is at the door, I can make him bark that way, oh and the home theater being on, and speakers all over the entertainment room, knocks on door coming from the back speakers makes him bark, and other dogs on animal planet can entice him also, hopefully you'll find something in here you haven't tried yet to entice a bark, thinking it's sad that Mabel's not been debarked, and nothing is found wrong, but she hasn't barked yet, Guessing some people are born mute, has Mabel at least whined or anything, like if she's in pain? any noise at all?