Overview of Protective (Territorial) Aggression
Dogs with protective or territorial aggression protect people or places regardless of whether or not there is an actual threat. Their response is inappropriate and potentially dangerous.
Protective (directed at protecting people, other animals, and objects) and territorial (directed at protecting their house, yard, or room) behavior is appropriate in actual threats, such as attacks or break-ins, but is not appropriate when a threat does not exist. Protective or territorial aggression may be directed at strangers (e.g., delivery person) or someone not well known to the dog (e.g., owner's friend). The dog may also inappropriately protect one household member from another (e.g., when children are roughhousing). Dogs without protective aggression usually give a low-level threat (bark or growl) then determine if the perceived threat is real based on the response they receive.
Dogs are instinctively territorial, but they usually protect their space by marking and posturing, rather than threats and violence. Dogs that growl, snarl, and lunge without first posturing, staring, and waiting are exhibiting territorial aggression.
To successfully treat protective and territorial aggression, it is important to accurately determine the precise situations that lead to the behavior.
Treatment for Territorial Aggression
Avoid all situations that elicit the aggressive behavior. If you cannot answer the door without the dog barking and growling, and the dog does not respond instantly to a verbal command to stop the behavior, put the dog behind a closed door or in its crate before answering the door.
If the dog growls or lunges, say "No!" and banish the dog from the situation until it is calm and responds to verbal commands to sit and stay. Removing the dog from attention and control for attention is one of the most effective and safest disciplinary actions.
Do not use physical punishment.
Avoid sudden arm gestures or motions that dogs with protective aggression often perceive as threats.
Dogs with that exhibit territorial aggression should be placed behind a secure door when any unknown person (e.g., repair person, delivery person) comes to the home and should never be loose outside or fenced into an area that a person may have access to.
If the dog protects an area within the house, change the area in which you keep it frequently.
Anyone that owns a dog should prominently display a "Dog on Premises" sign on their property.