Canine reactive behaviour is communication and isn't usually a measured decision by the dog but a nervous system response that they cannot control. This alone means that we cannot simply train a dog out of reactive responses without first teaching their nervous system that they are safe. 

This blog post is going to explain canine reactive behaviour from the dog's point of view, while also providing helpful tips if you're living or struggling with canine reactivity. 

When we feel overwhelmed, we communicate completely differently.

We have all probably experienced the kind of person who tries to control every social situation by talking louder than everyone else.

Interestingly, that’s usually the person who feels less safe than anyone else in the room, their coping strategy is just very well practised.

The man who talks over us is often protecting the child inside who is very scared indeed. The woman who goes into an emotional frenzy at the smallest inconvenience? She’s likely protecting a little girl inside who feels vulnerable in the situation.

The calm person, who looks comfortable in the face of adversity, not joining in, just being present—that is the person who likely feels the safest of all.

The human and canine nervous systems are not that different. 

• A dog who is scared might try to control a situation by being the loudest in the room, or nipping at people when they move (Collies are good at this) if that’s what they believe works for them. 
• A dog who is anxious might desperately ask for help by climbing up us and asking for space by screaming at anyone who comes close (My Chihuahua cross is very good at this).

An individual with a dysregulated nervous system is dealing with a body trying to attack or defend at all costs. This is the same whether it’s a bombastic or hysterical human, or an overreactive dog.

Nervous system responses create chemical reactions in the body. This occurs with the aim of creating a quick reaction to avoid or escape the danger in the environment.

How the nervous system responds is entirely based upon the experiences the dog has or hasn’t had in the past, along with any genetic stressors.

A dog doesn’t have to have been abused or traumatised to be reactive. Just a lack of positive socialisation can cause reactivity—and if it works, it will usually be repeated. For example, if a lunge towards another dog sends the other dog away, our dog can believe that was exactly what kept them safe.

It’s important to note, though, that if a dog interprets their own actions as keeping them safe in some way, they are not doing it from a calm and calculated state. They are in the same frenzy as the human who can’t cope and starts shouting. They simply can’t help it. 

Dogs don’t decide to show canine reactive behaviour from a calm state, they just don’t feel safe or believe they have any other choice.

Dogs are brilliantly honest communicators. They don’t hide their feelings behind social masks or polite smiles what they feel inside shows up loud and clear on the outside. We just have to learn to read it.

When a dog feels calm and safe, their body tells the story. You’ll often see a softly wagging tail, relaxed muscles, gently blinking eyes, and a body that seems to melt into its surroundings. They might sigh, stretch out, or lean their head against you in that unmistakable way that says, “I feel good here.”

But when something shifts, whether it’s a sudden noise, a strange dog in the distance, or even a change in your own tone of voice, their body changes too. Emotions rise, and the signals start to show.

It might be a stiffening of the tail, a frozen posture, wide eyes, or a yawn that isn’t really about tiredness at all. These signs are subtle at first, but they’re the dog’s way of saying, “I’ve noticed something, and I’m not quite sure about it.”

A dog might be comfortable and relaxed when something happens. Anything that changes how a dog feels is called a trigger. That trigger sparks a change in the dog’s emotional state. Then, that change becomes visible in their body language.

For example:

• A dog hears a sudden loud bang and instantly crouches low, ears back, eyes wide.

• Another spots an unfamiliar dog and freezes, tail straight, eyes locked, breath held.

• Or, a dog notices their guardian getting ready to leave the house and starts pacing, whining, or hovering by the door.

These physical responses aren’t random, they are information. The more we notice them, the better we get at understanding how our dogs feel, moment by moment.

The more we learn the better we can help our dogs feel safe.

Understanding your dog’s body language means looking beyond posture to notice expressions, shapes, and subtle micro-movements. 

The shape of your dog’s eyes, the position of their ears, or the way they lean into or away from something can tell you exactly how they’re feeling, if you know what to look for. For example, a slow blink, a lip lick, and an averted gaze can be a polite way of asking for space. 

Even in breeds like spaniels with naturally droopy ears, subtle signs like tension at the ear base or a furrowed brow can speak volumes. Sadly, many of these small but significant messages go unnoticed, and dogs who are simply tolerating something uncomfortable are often misunderstood. 

It is also important to remember that the same posture can mean different things depending on the context, like a play bow that is actually a signal for space if paired with tension and wide eyes. That is why it is vital to read the whole dog in the moment. 

One of the best ways to improve your body language skills is by learning your dog’s neutral — what they look like when they are calm, relaxed, and simply being themselves. From that baseline, even small changes can help you spot discomfort or distress before it escalates. When observing your dog (or any dog), always ask:

• What just happened before this posture appeared?
• Who or what is nearby?
• What has changed in the environment?

These questions help reveal the emotional story behind the behaviour and allow you to respond in a way that truly supports your dog.

A dog caught in reactivity needs nothing more than connection and safety. 

Unfortunately, instead, they more often receive correction and more reasons to feel unsafe. Trainers who do not understand the fundamentals of behaviour are very much into correcting fear-related behaviours, because it gets the results they want to see.

I even saw someone recently write that if a dog reacts because they are scared of something in the environment, the guardian needs to become scarier than what the dog is already scared of. 

Sadly, for dogs - there are too many uneducated dog trainers saying too much of the wrong thing. 

Can you imagine how heartbreaking it would be to a terrified dog who is desperately looking to their human for safety and trust, to be scared by their human too? The only safety they have?

Correction is not the answer for reactive behaviour—connection is. We need to show them we are their safe space, so that they can turn to us and trust us when they feel insecure.

Reactivity, sound sensitivity, clinginess, and emotional shutdowns are all telling us that the dog is NOT OK. Yes, they might be shouting their head off about it, but if they were feeling safe, they wouldn’t need to do that.

When a dog is not feeling safe, they might become highly volatile, they might bark and lunge, or they might simply close in on themselves and hide away. It’s crucially important to recognise the cry for help we call shutdown, as dogs are far less likely to be recognised in this state since they cause less trouble. They are still having an incredibly hard time, though.

It's so important to know what your dog is saying, when they are saying it, and what caused the response in the first place.

Learning body language, nervous system signs, and emotional cues gives you a new lens through which to see your dog. You don’t need to be an expert, just willing to learn.