Awww....Mike, that's so sweet about your guys, especially Rusty protecting the yorkies like that.
LOLOL....around here they are all good to let you know about the UPS man. But, if my life were truly threatened, the only one I would count is the poodle, Louis - he has seemed to make the connection that all food goes through/by me and if I'm not here....well then....no one eats - and that worries Louis!
I figure the dogs offer the first line of defense.....they bark to let me know....what I do after that is up to me. I don't ever see them as the types to try and bring down a cougar a la' Old Yeller style though