Over the years I have had several Doberman's, they have all had the instinct to protect family members. I went to work part time for the guy I bought them from since he was a professional guard dog trainer and K-9 officer in the local Sheriff dept. He taught me how to train a dog for guard and attack work as well as tracking. I have since trained every Doberman I have had, including not to take any food or treats from strangers. I walk him daily so he is visible in the neighborhood and he spends time in his kennel outdoors when I am home and can be seen by anyone casing the neighborhood. I believe this is a great deterrent to burglars.
I also have the security signs on my doors and windows. Knock on wood there has never been a problem with burglars or thief's in our neighborhood. In the very remote chance someone did get past my dog, I also have a very large and heavy gun safe in my basement. I ran a 220 line into the back of the safe and put a sign on the safe door saying "this safe is equipped with 220 volts to a mercury switch inside that will electrify the safe if any attempt is made to move it or break into it. Naturally it is not connected to power, but would you take the chance ?