Dog aggression and bite incidents don’t happen “out of the clear blue sky.” A dog will display precursor behavior (that a bite may occur) the owner didn’t initially recognize. In most cases, the dog has a heightened sense of fear to a stimulus (people and/or other dogs for example) or attempts to retain possession of a resource (food, balls, toys and/or you).
The dog “appears” to react in an aggressive manner to keep the unwanted stimulus away. If they aren’t successful, the fear biter has one last option, to bite. Since biting is a stress reliever for a dog, they are handling the stress in the only way they know. They are simply attempting to keep themselves safe.
When dogs become aroused, they can no longer think, only react. A defensive acting dog (growling, lunging, snipping, biting, etc.), learned this type of behavior worked for them previously. It made the stimulus go away. Therefore, as they rehearse the defensive behavior, they get better at displaying it.
If one responds to the heightened sense of defensiveness by harshly correcting the dog, it may look like the problem is solved but one has not worked on the underlying fear. Using corrections can result in the dog not showing the precursor behaviors (stressed looking body, growling, barking, etc.). When the dog can’t submit to the stress any longer they may bite without warning because the humans taught him if he gave warnings he would be punished. Therefore, it is crucial to work with the dog’s underlying fear to help him understand that the trigger is not as scary as he thinks. This is done by using Prevention, Management and Teaching new behaviors.