A Bull Terrier might have a preventive effect and it might defend it's owner in a truly critical situation, but it isn't bred to be a guard dog. Courageous, scrappy, fun-loving, active, clownish and fearless. The Bull Terrier is a loyal, polite, and obedient dog. They become very attached to their owners. The Bull Terrier thrives on affection and makes a fine family pet. Bull Terriers like to be doing something and fit in well with active families where they receive a great deal of companionship and supervision. They do not do well in situations where they are left alone for 8 hours a day. This breed can be a wonderful pet if very thoroughly socialized and trained.