Stranger Directed Aggression

Anthony De Marinis, CDBC, ADT, LFDM, FFCP, VSA-DT


February 8, 2023

A common problem among many dogs today is stranger-directed aggression. This is when a dog chooses to react towards a stranger or visitor out in public, in their home or on their property.


Dogs can display aggression towards strangers for a number of reasons, which may include:

  • feeling threatened
  • fear, anxiety, or stress a
  • resource guarding or territorial behavior
  • conflicted-related aggression
  • impulse control-related issues
  • overstimulated or sensory overload
  • frustration (also known as low frustration tolerance)
  • changes in the environment (also known as environmental contrasts)
  • trying to control the outcome of the environment or situation
  • instinctual behaviors and genetics can play a role. For example, purpose-bred or working line breeds such as Shepherd breeds and Livestock Guardian Dogs may have a higher rate of displaying aggressive behavior towards strangers due to their more protective nature. So yes, the breed of dog can play a role in aggressive behavior towards strangers and visitors.


Aggressive behavior can look very different based on the individual dog and the severity of the behavior. Dogs who display stranger-directed aggression may display the following behavior:  


  • Posture with their body in a stiff or arched position. Some other noticeable traits might be that the dog is very still. You may even see their hackles raised.
  • Lift their lip (warning signal)
  • Growl (warning signal)
  • Bare teeth (warning signal)
  • Snarl (increased warning signal)
  • Lunge (increased warning signal)
  • Muzzle punch- bumping or punching with their snout with a closed mouth (this is known as a closed mouth bite)
  • Air snap- biting the air. This is where a dog snaps toward the threat but does not make contact. People usually describe this as “the dog tried to bite but he missed because I pulled away fast enough.” However, the reality is in most cases, the dog strategically and intentionally missed. If a dog wanted to truly bite, we are generally not fast enough to move away in time. (This behavior is usually a final warning before choosing to bite.)
  • Bite without causing injury (a controlled bite or inhibited bite)
  • Biting while causing injury (to various degrees)
  • Attacking- I have this as a separate bullet point simply to point out that when a dog is attacking, they continue to proceed in biting multiple times, usually causing severe harm or death.


What is aggression in dogs?


The way I explain aggressive behavior is that it represents a broad spectrum of behaviors, ranging from minor posturing to serious and dangerous attacks. To learn more about aggression in dogs, take a look at the free webinar Micheal Shikashio has under the webinars section of his website.


Addressing Your Dog’s Behavior 

Firstly, I always recommend learning canine body language and communication signals. This is so important as learning and understanding how your dog communicates will help you understand how your dog is feeling which can prevent issues from occurring or escalating. Here is a list of credible sources to learn more about canine body language and communication signals.


Credible Canine Body Language Links:


Video’s on Canine Body Language and Communication Signals


If you are a dog professional looking to learn or expand your knowledge, I highly recommend checking out Sue Sternberg. Sue Sternberg is a dog trainer and professional who has dedicated her life to learning about canine body language, shelter assessments, and adopting out safe family pets. She has a wide variety of online videos and workshops. Her work breaks down every little detail in canine body language. I have never seen anyone read a dog or study a dog’s body language better than her.


The next thing to do is implement safety and management strategies as part of your behavior modification plan as this will keep everyone safe. Some safety precautions include, but are not limited to:

  • muzzle training
  • tethering
  • using a secure baby gate
  • crating in another room
  • meeting visitors outside on a secure leash
  • and more.


All of these suggestions listed above may require training your dog. For example, if you are going to use a muzzle, you are going to want to teach your dog about the muzzle by training them to like it or at least tolerate it. The same is true for using a tether or gating your dog off on one side of the house. You cannot just place your dog on a tether or behind a secure gate and expect they will just be fine with it. It is our job as dog owners to teach and guide our dogs to success. 


Implementing a Plan

There are a number of methods and approaches to modifying a dog’s behavior. Before I explain how I generally like to approach aggression towards strangers, I first want to say that this is a basic overview of what I may choose to do. This blog DOES NOT replace an individualized behavior modification plan and safety plan. 


Kim Brophey’s Off Duty Protocol

Certified Dog Behavior Consultant and Applied Ethologist Kim Brophey, has a protocol called the Off Duty Protocol. As described by Kim, “The purpose of the Off-Duty Protocol is to create a predictable pattern for dogs that are over-excited, reactive or aggressive when guests come to the home to settle down quietly at a distance from visitors through proper management and social signaling.” (FDM Off Duty Handout, Applied Ethology LEGS Family Dog Mediation Course, 2022) 


The way in which this is implemented is through the use of a secure tether system or secure gating system inside the home, with a dog bed and the dog’s favorite chew items. As the dog is calmly on his “Off Duty Station”, he will occasionally be rewarded for good behavior, such as simply chewing on his bone, staying calm, and/or minding his business. The goal is to teach the dog that he is “off duty” rather than “on duty” when visitors are over.


This protocol needs to be taught for one to two weeks before you decide to have a visitor over the home. Once the dog is able to enjoy or tolerate the Off Duty location, only then do you have a visitor come over. I usually recommend the visitor be someone the dog generally tolerates, rather than someone the dog doesn’t know or doesn’t like, as this can help set your dog up for more success in the beginning stages.


In general, when I work with dogs who are aggressive towards strangers, I find I have the most success when having the dog meet the visitor outside of the home to start. I ask the visitor to call or text upon their arrival and to be across the street or even two or three houses down the street. This allows for more distance to reduce the dog’s reaction towards the person. Make sure to have the dog secured to a leash, and muzzle if needed. Go for a parallel walk together where the visitor is across the street from you and your dog. When your dog looks at the visitor, reward your dog with a high-value treat like chicken breast, steak, cheese, etc. Using food like this can create a positive association where your dog can learn that the visitor equals something good!


In the beginning, meeting visitors outside the home and/or off the property removes the “surprise” at the front door. Removing the surprise of the visitor ringing the doorbell and entering the home can reduce some of the aggressive behavior(s). I find many times that the surprise at the door is the most triggering and causes more fear, anxiety, stress, frustration, and/or protective behaviors, which then causes many dogs to have an overreaction or more serious response towards the visitor. Remember, when you create more predictability and clarity in the environment, you have a better chance of removing stress, anxiety, and/or conflict.


To learn more about Kim Brophey’s Off Duty Protocol and all of the introductory steps, you can check out the Applied Ethology L.E.G.S Family Dog Mediation Education Center where I have a full presentation with a video on how to implement this protocol. 


Please be aware that the Off Duty Protocol should be implemented with a qualified professional to reduce the risk of any behavior getting worse. It is also important to be careful with this protocol if a dog is fearful, a resource guarder, or a flight risk as any of these issues can lead to a dog bite. Please consult with a professional to provide you with a behavior modification plan that will be best suited for your individual dog and situation.


About This Author: