My boyfriends dog is an Airdale Terrier, Border Collie mix. This dog has killed ONE cat, and multiple squirrels other verom etc. If you are acting like you are going to hurt my boyfriend, she will start biting you. He can make her bite other people too.
Shes VERY protective. It is really weird because she was never bred to be this way, it kind of sucks sometimes. We can't just leave her in the yard unattended because we don't know if shes going to find a jogger than looks suspicious and want to bite him..or if shes going to see a cat running and want to chase that. She doesn't like small dogs, but our neighbor dog is her BEST friend and they play like crazy little lesbian lovers.
She is the sweetest dog though once you get to know her, and very loyal.....shes just got this thing in her brain that says KILLL.
We do have a cat too, and shes just fine to her...they play like crazy little kids.

Dogs can be quite weird...