I know exactly how my two Mini Schnazers would react because I've seen it in action.... Cable man came one day to fix the outside line. I was home alone, he came in the back door without my "letting" him in. Bevo (gray 11 yr old MS) went at him and I caught him just before he took a hunk out of cable man's leg. A few weeks ago, son #2 was asleep (he works nights), so I asked son #2 to come mow the back yard (he was in between jobs and needed some cash) He went on in the back fence and started mowing - as per instructed so son #2 wouldn't be awakened - Ellie Mae (black 22 month old MS) heard the mower and could see "someone" back there (blinds were mostly closed) and did everything she could to get thru the glass of the french door to get at him. Though small, they would do everything they could to protect me... at least long enough for me to get to the shotgun! :D