I had a Cairn Terrier and he was a great dog. But he wasn’t afraid of anything. He was also friendly.
My folks had a male Cairn. A trespassing German Shepherd nearly killed him but he defended his territory bravely. He had to walk around for quite a while with an `Elizabethan collar’ bumping into furniture, door frames—it really hurt his dignity.
He was fearless, or as the Scots might put it: “doughty”. Most terriers and any given pit bull are not good company.