Sensitisation: why our dogs can struggle with the world

One of the our main aims for dogs who struggle in life is to help them get used to things. It doesn’t matter if they’re fizzy and frantic every time they see a duck or they’re anxious every time they see another dog. Getting used to things works.

Few of us ask why our dogs became sensitive in the first place.

This is an important question to ask.

Sadly, it’s very easy to end up re-sensitising our dogs instead of helping them get used to things. Instead of finding them calmer around lambs in spring, trying to help them get used to things can badly backfire. Or instead of getting used to people in cafés, they end up barking more and more. Some dogs unfortunately even end up getting much worse and going on to bite.

Trying to help our dogs get used to the world is a technique that most of my clients have already tried with varying success. It’s easy to get it wrong however.

What is sensitisation?

If habituation is a reduction in response to a stimulus, sensitisation is an increase.

What does that mean exactly?

The easiest way to think about it is with traffic noise. If you live in a busy city, you have hopefully got used to traffic noise. Life would be unbearable if you didn’t!

Through repeated exposure to traffic noises, you simply tune out a lot of it.

On the other hand, if you sensitise, you might end up noticing even the quietest electric milk float going by at 5 in the morning.

It’s not that your ears have stopped working. You’ve not over-used your auditory pathways. You can still notice things with your ears. It’s just that you’ve become accustomed to traffic noise through repeated exposure. You got used to it.

Sensitisation is the opposite. Instead of getting accustomed to traffic noise, you notice it and respond to it even more.

Why do animals habituate or sensitise?

Wouldn’t it be great if we could simply get used to everything? Nature has given so many animals the ability to first notice novel things in the world around them, and then the ability to tune them out.

It never failed to astonish me the day I heard a field of cows letting me know that my dog Heston had sneaked in. He was nowhere near them but they certainly noticed the new arrival in their field. The calves were panicking as you might expect. The mothers were responding with alarm, as you would definitely expect.

Heston, however, was focused on making his way through the field exploring other things. It’s not that his eyes were incapable of seeing the cows. His ears definitely still worked. It’s just that he’s seen cows and been around cows so many times that it’s almost like they weren’t even there. He’d habituated.

This is often a dream for many of us with our dogs; I can’t tell you how many times I’ve prayed that my other dog Lidy had habituated to cats rather than noticing every single one and responding intensely.

We habituate in life to things that are of little value to us. The cows had no value to Heston. He was neither scared of them nor wanting to chase them.

We sensitise when things are intense. This is a temporary process that’s not connected to rewards or punishments. It’s a useful tool in our behaviour so that we can temporarily pay more attention to relevant stimuli in the world.

Like if there’s a storm, for instance. Temporarily sensitising to the thunder can keep you seeking shelter and safety. It simply readies us for the next unpredictable delight or danger.

Habituation sounds great – how can we get that?!

Of course, few of us want our dogs so sensitive to the world that they are excited or afraid every single time anything different happens. We definitely don’t want our dogs to sensitise to the neighbourhood cats, or when next door’s dog barks.

Habituation, please!

If only it were so easy!

One reason that researchers think we might sensitise instead of habituating relates to arousal. When our dogs are in a state of alertness, it makes it very easy for them to sensitise rather than habituate.

It’s not much different for you on fairground rides and at fireworks night – the alertness contributes to the pleasure you’ll feel.

Another reason researchers think we sensitise rather than habituate relates to emotions. When we’re in a state of anticipation – like excitement or anxiety – it makes it much more likely we’ll sensitise. For example, if you’re all waiting for New Years Eve chimes to go and someone lets off a party popper when you don’t expect it, you might sensitise. Or if you’re walking down a dark alley and you’re anticipating threat when a branch touches your arm, you might also sensitise.

The third reason relates to the intensity of the stimulus. The bigger or more intense it is, the more likely we are to sensitise.

Sensitisation is also less likely to happen if we’re mildly occupied by something else. You’ve perhaps had that moment where you were lost in what you were doing and someone had to really try hard to get your attention. Of course, complete immersion in another task can make sensitisation more likely when our attention is so narrow that things then startle us.

We’re also more likely to sensitise in novel or unfamiliar surroundings.

Types of sensitisation

We can sensitise to both pleasant and unpleasant experiences, just as we can habituate to them. For example, I hope you’ve had the delightful experience of sensitisation when you’re involved in a romantic liaison. Nobody would want to habituate to romance!

Restaurants may go out of their way as well to play on sensitisation. Dans Le Noir is a chain of restaurants who deprive you of light so that you are more sensitive to the flavours and smell of the food you are eating. Varying tastes, textures and odours can also avoid habituation – the bane of any wine connoisseur or foodie.

Music also plays on our sensitive ears. You didn’t think all the fireworks and lightshows and anticipation before a rockstar comes on stage was for nothing, did you? It improves your experience of the event.

Sensitisation can be quite delicious when it’s to positive experiences.

Little wonder, then, that our dogs can sensitise to squirrels, to chasing cars, to other dogs or even to the sound of a packet that you’re trying to open quietly in the kitchen. Anticipation, arousal and excitement all play into why they are likely to sensitise. This is also true if they experience something wonderfully and powerfully exciting.

On the flip side, we can also sensitise to the bad stuff in life. This is especially likely if we’re highly aroused, if we’re anxious, if the trigger is very intense, if we’ve sensitised in the past or if we’re on the look out for trouble. It’s easy then for our dogs to sensitise to thunder, to gunshot, to fireworks or to other negative experiences.

Two sides of the same coin

It’s easiest to think of habituation and sensitisation as two sides of the same coin. When we encounter new things in the world, it’s a bit of a coin toss as to whether we’ll sensitise or habituate.

However, it’s not random. Even though this imaginary two-sided coin can only land on one side, what makes it likely to land sensitisation-side up depends on a number of factors.

What is important is that we understand that while it’s complicated that we’ll sensitise, it’s not unpredictable. The more factors are in play, the more likely it is that we’ll sensitise.

For our dogs, that can include the kind of triggers in the world that they’ve been selected to notice over generations. A continental shepherd dog, for instance, in lowland pasture country, is selected not only to notice the energy of the flock, but also to notice potential threats. Like livestock guardian breeds, they are more likely to be easy to sensitise to the movement of potentially threatening animals or humans.

For a border collie, selected for their ability to notice movement and collect flocks together, it makes it more likely that they’ll notice other moving things and sensitise to them. It’s not unusual, for example, that they will sensitise to moving visual stimuli.

Our dogs can come with evolutionary legacies that make it easy for them to sensitise. When we add in sensitive developmental periods, poor inhibitory skills, novelty-seeking tendencies, bold personalities, we see that there are even genetic components that contribute to why the coin lands on one side or another.

Experience and learning add to those components.

Neural changes through repeated sensitisation

One crucial factor about sensitisation is that prior sensitisation makes it easier for us to re-sensitise.

Each time the neurons that fired together in the initial experience fire together again, the easier it gets for them to re-fire together again in the future. Neuroscientist Donald Hebb said, ‘neurons that fire together wire together’ in the 1950s. What this means is it simply gets easier for our brain to ‘remember’ that earlier experience.

We can think of this like ‘desire paths’. In the landscape, even if there are neat paths laid down for us, we often take a shortcut. Sensitisation just means a shortcut path gets so well-trodden over time that we default to it.

In our physical environment, repeatedly re-tracing this shortcut makes it harder for the shortcut to re-vegetate. For neural assemblies, repeatedly re-tracing this shortcut makes it easier for us to default to it in the future.

We can think of habituation as having the opposite effect. That takes us on a different pathway. The same is true for habituation, by the way. The more well-trodden the ‘habituation’ pathway is, the easier it is for us to default to it.

What this means for our dogs is that if they have a strong history of habituation to specific things in the world, it makes it less likely that they’ll sensitise. For my dog Heston, for example, he grew up around fast traffic on the road. On walks, it was almost as if he did not notice the cars.

Long-term habituation like this does not mean we’re completely oblivious to the world. If a car beeped or drove very close to us, Heston would of course notice it. But because of that well-trodden habituation pathway, he’d be unlikely to sensitise to the next few cars along.

Effect on behaviour

Sensitisation changes our behaviour. Sometimes that can be temporary. At other times, it can be more long-term. Long-term sensitisation is likely as a result of traumatic experience or continually repeated exposure at high intensity. This is especially relevant if the dog was physiological or emotionally aroused and if the trigger was very intense.

What we might expect to see as a consequence would be an increase in the intensity of a reflex response. For instance, for one of my dogs Flika, she was extremely sensitive to traffic and had a long history of chasing cars before she arrived with me. Although we took the path to habituation many times, it was easy for her to re-sensitise. What I saw when that happened was a bigger startle response to car noise.

This also seemed to knock her off-kilter. It took longer for her to recover once she’d startled.

It may also take less of the trigger to cause the response. For example, it would take an extremely fast, close or noisy car to attract Heston’s attention. For Flika, even very distant cars that were very quiet or slow could grab her attention.

Managing the world to avoid accidental sensitisation

We can make some choices to avoid initial sensitisation. This is more likely at four points in a dog’s life.

The first of those times is when we have a young puppy between the age of six weeks and fourteen weeks. During this highly sensitive period, long-term habituation is possible. This is what we think of when we ‘socialise’ our puppies. We’re really talking about long-term habituation that is very difficult to disrupt. However, it can easily go the other way.

I don’t have to tell you how wrong it can go if a sensitive collie puppy is taken out just at the most exciting time of their life, filled with uncertainty, anticipation, excitement and arousal. If we don’t work sensitively around livestock, wildlife or moving vehicles, we can find that we’ve accidentally sensitised our puppy instead of helping them habituate to things.

The same is true during adolescence, when we need to work carefully. There is some research to suggest it is much more challenging to overcome specific types of sensitisation during adolescence. Not only that, our adolescent dogs can be more sensitive to threat but also to reward. The world just gets easier to sensitise to for an adolescent dog.

When we change context and things become less predictable or familiar, it can also make it easy for dogs to sensitise. This can happen if we move home or go on holiday. It’s not unknown for people to take their adolescent dogs on holiday and find that they’re much more sensitive to the world – even to things they were familiar with at home.

This is especially true for rehomed dogs. It doesn’t matter if they’ve been rehomed next door or in a completely different country. Everything is more arousing and stimulating as well as unpredictable.

And when it’s all gone wrong?

The most important thing to do is to take it easy. Sensitisation is a temporary process on the whole. Giving time for the body to reset is helpful.

If our dogs accidentally sensitise to bad things in life, it can help to bookend the experience with fun things. Going to do something fun and pleasurable straight after can make a real difference. We need to be careful that this experience won’t frighten our dogs and we take it easy, but in that heightened state of awareness, it makes the good stuff more fun too.

For example, a couple of years ago, I was walking in the forest with my dogs when two very speedy (and inconsiderate) mountain bikers rode past very close and very quickly. No harm was done but it really startled both the dogs I was walking. Instead of going home and resting, we went for churros and a swim. Churros are obviously bad for dogs, but very delicious. They were also a novelty. Both my dogs enjoy swimming.

I wanted that to be the experience the brain would latch on to, not the startle to cyclists. It had taken a long time to help both my dogs get used to cyclists!

I also did a little bit of habituation over the next few days, treading very carefully and keeping sessions short.

Knowing that being startled was likely to cause further sensitisation and taking some preventative measures really helped.

Further support

You may find these two courses useful.

Effective Safety Cues for dogs can help with dogs who have a long history of sensitisation and associated learning.

The Resilience Roadmap is an outline to recovery if your dog is very sensitive to either the good stuff in life, or the bad.