Dogs that lack confidence often times feel threatened by seemingly innocuous stimuli and then act out in a defensive manner. Barking, biting, growling, showing teeth, etc. are the most common defensive reactions. These same dogs will bond very closely to their families (both human and dog). These types of dogs are often perfect with their families but far from it with others. It is important to be patient and consistant in working with defensive dogs.
When we work on these issues we approach them on three fronts:
-Obedience (so that you gain better control and "lead the dance". This also gives the dog structure on which it can rely.)
-Socialization (so that the dog gets more positive experiences in all environments)
-Correction/Reprimand (to show the dog which behaviors are inappropriate)
Part of the overall solution is having the people gain confidence in handling the dog. This is an important aspect since the dog seeks your leadership. When a handler is nervous or even just indecisive a dog reacts instinctually... in these cases, defensively.