i agree you should tel ya missus, but say something like "have you noticed the gates been open in the morning?" and see what she says, so you're not actually saying "someones trYing to burgle us rah rah rah " lol then put the security light up, she'll feel safer too. and put a sign up "beware of dog" (pic of rottweiler)

they'll notice you've noticed somethings up, and hopefully that'll be enough to scare them off. if not. camp in ya car and then GET THE FOOKERS