Design the place so that the only ways in are through the doors. Then get some pressure sensitive mats and wire them to some sort of alert system in the master bedroom, maybe an audible alarm to wake you up and just an alert strobe in the other rooms. You will know the moment anyone is standing at the doors. No dog Required. You can load a few Colt SAAs in the time it takes to pick a lock or break down a decent door.
"Jack Bauer sleeps with a pillow under his gun."
"Bush is listening, use big words."