The dog reacts disproportionally or inappropriately to something, such as excessive barking, or becoming over aroused.

The motivation for the behaviour might be different – barking may be your dog’s way of telling you that he’s frightened by what he’s barking at or maybe your dog is so friendly that he gets extremely excited at the thought of being allowed to greet a person or another dog?  Either way, when a dog over reacts to something, also called going over threshold, the part of the brain that deals with reasoning, impulse control and learning is compromised and more primitive behaviours take over, such as barking.  A dog that’s barking probably can’t learn in that moment not to bark.


For most dogs it will be reasonably obvious, particularly if they’re barking.  However, there is a test that you can do.  If the dog won’t eat a treat that he would normally like, then he’s over threshold and can’t learn.  If he eats a treat but grabs it from you, he’s very close to his threshold and is probably not learning much.

The things that cause the over reactions are known as triggers.


Dogs have ‘bubbles‘.  When a trigger enters that bubble, the dog will cross over threshold and is likely unable to learn at that point.  That means that when the trigger is present, but not within the bubble, the dog can learn things that will help change his response.  Distance is key in order to help your dog learn to not over react.  It should be noted that

  • the size of each dog’s bubble changes
  • the shape of each dog’s bubble changes


Each dog’s bubble will be differ in size – the more fearful or excitable the dog, the bigger the bubble.  In addition to that, the bubble doesn’t stay the same size!  The size will vary depending on what experiences the dog has had within the last 72 hours, this concept is known as trigger stacking.


Let’s say that today your dog’s bubble is 3m.  You start your walk in an open field, so the bubble is round with a radius of 3m.

You then go into a lane that is 2m wide, the bubble is now rectangular.  If you come across a trigger, that trigger can’t pass without entering the bubble, causing your dog to over react.  Not only that, but because the bubble has become narrower to the dog’s sides – the dog needs 3m, but can only have 2m, it means that the amount of space required in front and behind has increased – the 1m that the dog has lost to the side has been added to the front and back.  Rather than the dog needing 3m in every direction, he can only have 2m to the side, which means he now needs 4m in front and behind.

Once you get the hang of the bubble, you can take steps to avoid the trigger, such as a dog or a person entering the bubble.  Don’t worry, for most dogs this will be temporary.


Trigger enters the bubble = dog over reacts = dog stops being able to learn

The rule is simple – distance is your friend.  Simple, but not necessarily easy, as you can’t always control everything in the environment.

One of the simple things you can do it change the dog’s association with the trigger.  Most dogs love squeezy cheese!  The way it’s packaged means it’s quite convenient to take on walks.  Now, it’s obviously not a healthy treat, but we don’t always eat healthily.  The amount of cheese that you use is small, it’s mostly licking and licking promotes calmness.

This is how you’ll practice.

  • Choose an environment where you have as much control over your dog’s bubble as possible – National Trust areas are often good choices as I think with most venues dogs should be on lead.
  • Don’t do this if your dog is ‘misbehaving’ – it’s likely that you’ve misjudged the size of the bubble and it should be bigger.   Remember that the dog can’t learn if he’s over threshold.
  • When your dog notices the trigger, present him with the squeezy cheese immediately.
  • Whilst the trigger is present the dog can lick the squeezy cheese.
  • When the trigger is out of the dog’s eye sight, the squeezy cheese stops.

The squeezy cheese is not being used as a reward in this exercise.  The point of the exercise is not to reward for not over reacting – the dog has no need to over react as the trigger is outside of the bubble.  We’re using classical conditioning, which we know can take some time to work, to change the dog’s association, and therefore the dog’s emotional response.  Over time your dog’s association with the trigger will change from, for example

another dog = scary/exciting = barking


another dog = squeezy cheese = happy/calm = no barking

As a by product of this the bubble naturally shrinks as the trigger is no longer eliciting the emotion response that is was, and therefore the resulting behaviour disappears.

With some dogs simply practicing this will sort out the problem behaviour.  With other dogs you’ll now be able to train a more appropriate behaviour since the dog is calmer in the presence of something that he was previously over reacting to.