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  • Writer's pictureRenée at Bravo Dog

WHY does my dog have reactive behavior?

That is the million dollar question. And of COURSE we want to know why! It's human nature to want to understand what is behind the behaviour that we see in our dogs. It's often even more difficult because dogs cannot verbalize and let us know how the experiences in their lives have impacted them. I'll share some of the most common reasons why dogs can display reactive behaviour.

What is reactivity?

We can summarize reactive behaviour by stating the following:

An over-reactive response to a common stimulus typically triggered by an emotional response. This can appear as barking, lunging, growling, pulling towards a trigger, rearing on the back legs, redirecting onto the guardian (especially when on leash). It can also appear as hyper-vigilance and escapism.

Dogs that are in a reactive state are "over threshold". I like to explain this to clients by stating that our dog is not in "thinking brain mode". They are not able to respond to much of anything in that moment. This is NOT the time to initiate training, it's a time to create distance for our dog from whatever they are reacting towards so that they can decompress from the event.

Angry or Fearful? More Like Fight or Flight

I truly believe that fear is one of the most misunderstood emotions that our dogs experience. Their body language and physical responses are often labelled "mean" or "angry". I have even seen the label of "overly confident".

Fight-or-flight response

First, it's important to understand what the fight-or-flight response is. The fight-or-flight response is a primal instinct triggered by a perceived threat, releasing stress hormones like adrenaline and cortisol. This physiological reaction prepares individuals to confront danger or flee from it, with changes in the body enhancing physical abilities. This is typically what we are seeing with our dogs reactive behavior.

Fight Response: Fear often initiates behaviour that creates distance. Barking and lunging typically achieves that result. Dogs can't cry like humans if they are fearful. They use behaviour that works for them and often times their reactive behaviour does just that! This would be considered the Fight response.

Fight response

Flight Response: Fear can also manifest as avoidance, shaking, panting, trembling and escapism. Dogs that are getting low to the ground and pulling hard on leash away from triggers are often fearful. The dog is trying to escape from the stimulus that they feel threatened by.

Fear response

Why Is My Dog Fearful?

  1. Negative experiences and less than ideal socialization before 14 weeks of age.

Could your dog have had a negative experience or several that then result in your dog becoming fearful? Absolutely! But, many dogs are fearful of certain situations, environments and stimulus as a result of not having positive experiences or exposure to them before 14 weeks of age. Some dogs may have never been socialized to walk on a leash or to live in a busy environment. If that was the case, we cannot "socialize" them again. It doesn't work that way. We need to work on behaviour modification exercises to hopefully help change those negative associations.

Fear is extremely difficult to change but very easy to install.

It doesn't have to make sense to you. This is your dog's experience in life. Many times my clients will say "they didn't have any negative experiences", however, that is likely not the case. You may not have seen that interaction, you may not have understood how your dog processed that interaction. This is not to say that you can control how your dog processes experiences so please, don't take this to mean you are to blame. This is purely for awareness and education to help you understand your dog better.

2. Genetics

Many dogs are genetically predisposed to fearful or frustration based reactive behaviour. Dogs at risk are those offspring from dogs that are already reactive/fearful. We can also see maternal stress and maternal care impact dog behaviour and temperament.


I see this a lot with dogs that are very social off leash but as soon as they are on leash, they become very frustrated when they see another dog. This is the most common scenario with frustration and it takes an incremental plan that incorporates a variety of techniques to help your dog cope with that frustration. Some dogs have a genetic propensity that results in low tolerance to frustration. I won't go into specific exercises to help with frustration as we certainly can do that working together if you choose :)

Resiliency and Coping Mechanisms

Just as in humans, some dogs have a difficult time processing and recovering from stressors. Resiliency has a genetic component however it's always nature vs nurture. Dr. Patricia McConnell believes we can build resiliency in dogs as adults. Watch the interview here!

Many factors will impact how your dog copes with daily interactions. Their history, past trauma, their genetics, their health... this stuff is complicated!

Pain and Illness

Underlying health issues are a big contributor to reactive behaviour. Some statistics show that up to 80% of veterinary behaviourists attribute pain to reactive behaviour.

Dr. Daniel Mills, a leading veterinary researcher has published several studies that demonstrate the need for pet parents to delve deeper into whether pain is impacting their dog. Often times pain is not visually identifiable. Our dog's can be VERY stoic when it comes to showing pain physically so you may not see your dog limp but their behaviour may be the manifestation of that pain. Take a look at a prior article I wrote discussing this topic and how you can discuss this with your veterinarian.

Approach Matters

If you've reached this point in the article, you can now see that our dog's are struggling when they use reactive behaviour. Knowing that so much of their behaviour is a result of genetics and experiences we definitely don't want to suppress behaviour with the use of corrections, tools and our own behaviour. That is unfair AND will cause further damage.

Remember; this is a journey NOT a race. The fix-it mentality will only set you and your dog up to fail.

Compassion, a plan and a team that supports you and your dog is your best approach when you are struggling with your dog's behaviour.


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