Thanks to everyone who has provided their insight. I knew I could count on the CA brothers. I will certainly be investing in an alarm system. The police pointed it out immediately (with a bit of a "what the hell are you doing without an alarm?" attitude).
The break-in occurred between 5-10 AM. My house-sitter was at work, but it was not his routine schedule. He usually works 9-5. This was on xmas day and he was just finishing up some stuff before taking vacation time. In other words, on any other day he could have been in the house during the break-in (had it been premeditated). I am willing to assume that they saw that the car was gone before deciding to make a move though.
No kids in the house. But my girlfriend is on-board with taking HD classes.
My dogs are not the most intimidating, 2 Schnauzers. But they do bark up a storm when someone comes near the property. The one that got her butt kicked is the protective one. She WILL bite if she is threatened. I am assuming that is what happened. Here is a pic of her:
