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ReactivE Behaviour?

What is reactive behaviour? And why do some dogs show it in certain situations?

Dogs are social animals that interact continuously with their environment. When something in the environment changes, dogs are triggered to respond to this. If the dog feels he’s in a situation where he isn’t able to cope with the changes in a proper way, he may respond with an overreaction to this stimulus. 

If a dog is exposed to such an overwhelming situation, he undergoes an emotional change. Linked with this emotional change, physical and behavioural changes will follow automatically. For these external changes a dog relies on his behavioural repertoire and will select from any of the “4 F’s”: fight, flight, freeze and fiddle.

Each individual dog will have his own preferred response. Depending of which one that is, the shown behavior will differ enormously. But the underlying reason (emotional change) is always the same.


 Reactive dogs in “fight-mode” are loud and animated. They lunge, growl, bark, make themselves big and will do everything to be perceived as impressive. A dog that shouldn’t be messed around with! They are actually trying to chase away the thing that scares them.



Freezing is another ingrained survival response of animals. Standing completely still and trying to be invisible for that which triggered the response. Dogs in this mode will suddenly stop and are not willing to move closer. In some cases this behaviour precedes the flight response. Where freezing was the initial response and after re-evaluating the situation, the dog chooses to retreat (flight).



Another easy to identify response is “flight”. Instead of trying to chase the scary thing away, the dog desires to leave the situation himself. When a dog is on leash, this often isn’t possible at all. In this case the dog will show this by hiding behind the owner, trembling, making himself small or pulling away.



The last F is “fiddle”, least known and often misunderstood. This behavior is more difficult to identify. Fiddling dogs behave clownish, they are trying to remove the tension out of the situation by acting foolish. They will often jump-up, turn around, act overenthusiastic and puppy like. This is similar to people who start telling jokes in awkward or stressful situations, to lighten the mood. Fiddling dogs can also present a range of other appeasing behaviors, like paw lifting, rolling on their back and urinating


Common Causes

If reactivity is an overreaction to something in the environment, what is causing this overreaction? Why do some dogs react in such an exaggerated way?

In most cases reactivity is fear-driven. This means that the dog feels frightened by the situation and has got the feeling he is forced to defend himself. Crucial here is that if the dog perceives something as a threat, he will react to it as if it is an actual threat. It doesn’t matter if the threat is real or not. Fear could be rooted in:

  • a previous traumatizing experience

  • repeated unpleasant experiences

  • social deprivation,

  • learned association

  • genetic predisposition

  • an overall distrust for anything new due to medical reasons

Sometimes reactive behavior isn’t caused by fear, some dogs get so excited when they see other dogs / triggers  working themselves into a frenzy. They get frustrated because they aren’t able to get closer and show this frustration by lunging, barking, … This is common in young adult dogs who, as a pup, where allowed to play with every other dog / pup they saw. When they grow-up, and this is no longer possible, frustration starts to build-up.

Due to the intensity of reactive behavior, especially in fight-mode, and the impressive display that is associated with it, reactivity is often misunderstood or wrongly interpreted as so-called dominance or aggression:

  • Aggression is an emotion, meaning that the dog is angry. Feeling angry in certain situations is normal and natural (part of the dog's ethogram). Aggressiveness is thus not a temperament trade of an individual dog! There are no “aggressive dogs”, but dogs can be pushed to be angry and display aggressive behavior.

  • The dominance or pack theory, which is currently outdated and obsolete, is sometimes still used to explain reactive behaviour. Linking every (unwanted) behaviour of your dog to a social status issue, is a narrow-minded way of interpreting the emotional pallet of your dog. Reactivity has got nothing to do with a social position or dominance what so ever!

Triggers & Threshold

A dog can be reactive towards people, dogs, bikes or any other objects. The thing that causes the reactive behavior is called the “trigger”.

Each reactive dog will have his own trigger(s). As an owner it is important to identify the exact triggers of your dog and identify them very precisely. If a dog is reactive to other dogs, is he triggered by all breeds? By big or small ones? By both sexes? If a dog is reactive to people, is he triggered by children, women or men? Or maybe by a certain coat, hat or umbrella worn by people? The more you are able to isolate the exact trigger(s) of your dog, the easier it will be respond to them.

The threshold is the level at which the dog perceives the trigger as too intense and responds by displaying reactive behavior. The intensity of the trigger is in direct correlation to the proximity of it. Trigger stacking is a phenomenon that occurs when a dog reacts to multiple triggers that are presented simultaneously. Any of the individual triggers would not push the dog over threshold in that situation, but because the dog is exposed to them all at once the intensity is too much and he reaches his threshold.

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