Trigger stacking in dogs and why he might react when you least expect it.

It seems like there is some confusion regarding articles about trigger stacking in dogs. Let me try and simplify what it is all about and why every dog expert is so against small children playing roughly with dogs.

Let me start by saying this. Every dog is an individual just like people. Every dog reacts differently to different situations. Anxious dogs will react differently to laid back dogs when confronted by certain things. Different types of dogs will react differently to the same situations. Having said that, every dog has a reactivity threshold, that is the point where they become reactive to a situation instead of almost ignoring what is happening. You can compare it with yourself. You might be a calm and collective person, but at times you will reach your reactivity threshold and lose your temper. Well, dogs are no different. So how and when will this happen?

Let me give you 2 scenarios. The only variable that will change is the time frame within which these events occurs. Let’s say you have a dog who you fully trust. He has never shown any signs of reactivity and gets along very well with your 5 year old child. He is the best dog in the world. You take your dog for regular walks and nothing he has done has ever suggested that he will bite anybody, let alone a member of the family.

Scenario 1:

One day you take your dog for a walk. Another unrestrained dog comes running up to you but all is fine. Your dog shows no signs of reacting. He is such a good boy.

The next day your neighbour’s cat jumps the fence. You can see he is a bit uncomfortable but all is still fine. He barely reacts when the cat runs away.

Then the following day you have a party and you invited a few friends. Your dog is not used to this but is coping well. He is lying outside on the grass and now and again he just comes in to see what is happening. He is uncomfortable but again he tolerates all the people around.

The next day is Sunday. Your child plays with your dog by pulling his ears and jumping all over him. He looks away and you can see him licking his lips but you are not concerned because you know he is really such a good dog. He has always tolerated everything you dished out to him. What an amazing dog! He will never ever hurt a fly. You completely trust your dog with your child.

A few weeks after this, after another party at your house your dog gives your child a serious bite in the face. How is this possible? Your dog has never bitten anybody and now he’s bitten your child? A normal parents reaction would be “I am having him put to sleep, I cannot trust my dog anymore”.

So why did this happen? One reason might be trigger stacking. Let us take the same events, but change the timeframe that they occurred in.

Scenario 2:

One morning you get up and you take your dog for a walk. Another dog approaches but your dog doesn’t react at all. Good boy!

An hour later your neighbour’s cat jumps the fence. Your dog barks at her but still don’t show any signs of really reacting. You can just see he is now a bit uncomfortable. Well, he did not kill the cat so he tolerated that as well, good boy!

Two hours later your party guests arrive. You can see your dog is a bit stressed and is showing some signs of anxiety. He walks outside and goes to lie down. He is such a good boy, he knows he must stay out of the way at these events.

Party over and now is time to relax. Your dog is lying down in the kitchen. You have watched this a million times before as your child makes her way to your dog. She starts pulling his tail. He is such a good dog!! She stumbles and falls on top of him. He reacts very very quickly with a bite to her face. BAD DOG. A normal parent’s reaction again would be “I must get rid of this dog. I will take him to be put to sleep”.

Now let’s go back and figure out where it all went wrong.

You see, every time your dog gets stressed by an event his body reacts by releasing 3 different hormones to help him cope with these events. These 3 hormones are responsible for the fight or flight reaction to a potentially dangerous (in the dog’s mind) situation. One such hormone is called cortisol. Once this hormone is released, it takes time for the body to get rid of it and to return to a normal relaxed state. It can take 5 to 8 hours for his body to totally remove it.

This explains why nothing happened in scenario 1 because when the other dog approached he was in a calm mood state and between each of the subsequent events happening there was sufficient time for the cortisol levels to return to normal in his body, thus he was better able to cope because he was below his reactivity threshold for each new scenario.

In scenario 2 however, things were a bit different. Every stressful event happened in close proximity in time. When this happens it all starts building up inside your dog. Not enough time passes for the body to return to its normal calm state. The second scary stressful event starts way before the hormone levels have returned to normal so he feels more and more stressed.

Then your party starts. It is really scary for your dog and he prefers to avoid the situation by being on his own outside. This is now the third stressful event in a matter of hours. Once again this increases your dog’s stress level and by now your dog is near his threshold. He is still coping, but only just, and you don’t really notice what he is going through. Your dog is the perfect dog, he will never harm anybody.

Then after the party you start to relax. Your dog is now lying down in the kitchen. You love it when your child plays with your dog. Your dog has never showed any signs of reacting so it is safe. Your child walks up to him and pulls on his tail and ears. He still tolerates it but then it happens. She slips and falls on top of him. This last scary event releases even more cortisol and he passes his threshold and bites her in the face. Now who is to blame? When it happens to you who do you blame?

Every dog has a reactivity threshold. Some might take a long time to reach it and others might reach it very quickly. Remember too that a dog who is suffering any type of pain from ear ache to arthritis has less tolerance – just the same as people, and will go over this threshold a lot quicker than people anticipate. The thing is, to let children interact with dogs in these ways might push them through their thresholds and it will not be their fault if they bite. Dogs give off many signals to indicate that they are not comfortable with a situation- licking their lips, turning their heads away, lifting their lips to expose their teeth and growling but people, and especially children, take no notice, so when he gets pushed too far and he crosses the threshold and bites, he does this because all his other attempts to get you/your child/strange people to stop what they are doing have been ignored because he is “really such a good dog”!

That is the reason why behaviorists all over the world are so against pictures of children standing on or tormenting dogs. You as the owner may not realize how close your dog is to his threshold at the stage your child starts interacting with him. ANY dog has his own threshold and people tend to think that it will never happen to their children. This is only one of the reasons why dogs might reacts when you least expect it. So the bottom line is, dogs should be respected. Believing that any dog will never bite is like saying any person will never in his lifetime ever lose his temper. Rather be safe than sorry and teach children to respect dogs.

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George van Huyssteen (DipCABT)
Practitioner Member CAPBT International
Garden Route, South Africa


Petra du Toit (CPDT-KA)
SABCAP Companion Animal Behaviorist (AB/013)
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