This is why there's a little over 300 lbs of canine running around my house on 12 legs. In eight years of law enforcement, I never worked a burglary or home invasion at a house that had a dog. I'm sure it happens once in a while, but the bad guys tend to skip houses if they hear barking. And my house doesn't need a beware of dogs sign either, thanks to the front bay window with the pit bull perch.
Maybe this evening I'll add a photo of what this looks like from the outside (potential burglar point of view).