To express a fear of xeno's?

When my inlaws moved to a senior residence we inherited their pitbull named Xeno. His job prior to FIL's retirement from PGE was protecting the PGE troublemans cherrypicker truck.

As a housedog he loved to run the perimeter of the yard warning off pedestrians. He would hold houseguests hostage in the guestroom at night as we slept. Xeno lay on the hall carpet by the guestroom door. His low grumbly growl everytime the guest turned the doornob, convinced guests that opening the door might not be a wise choice.... so couldn't get to the bathroom 4 feet down the hallway. |As soon as we woke up, Xeno relaxed and the guest was able to come out of the guestroom.

He instilled fear in more than a few folks, but with us was sweet as could be until, trying to break up a fight he started with a pair of shepherds on our front lawn, he bit my hand. We returned him to my FIL who 'found him a ranch to live on.'