We have a male and a female Great Dane who patrol the house. Unless she's bred, in which case we separate them, or unlesss we have pups that haven't sold yet.
I had the male for about a year before I met my wife and that fucking traitor is 100% her dog now. Aint NO ONE messing with the Messican gal while that dog is around. The female, she looks just as tough, but is much more laid back , UNLESS she has pups.