Trigger Stacking

By Abby Huxtable

Have you ever found your dog reacting in a situation they wouldn’t usually react to? Or have they suddenly had a severe reaction to something they aren’t usually bothered by?

You have no idea why they have suddenly reacted like this when they wouldn’t normally. Well this reaction is likely due to trigger stacking.

My favourite analogy for this is a bucket. Your dog’s bucket holds ten litres of water. Every event in your dog’s life adds or takes water out of their bucket. However, if the bucket reaches that ten litres, it will overflow and your dog reaches their threshold and reacts.

Each dog will have different values to things they experience. For example, food may be one litre, play may be one litre, the postman or doorbell may be three litres, a cat could be two litres. A calming activity like scent work may be minus one litre, chewing may be minus one litre, a massage from your owner may be minus one litre.

The other key thing to remember is that cortisol is a stress hormone. This is produced in our dogs in exciting or stressful times and can take up to 72 hours to leave their bodies. That means you need to consider your bucket over a 72-hour (three day) period and even longer if you have a series of threshold events.

Let’s look at this in a real-life scenario. Most dogs will hover around four of five litres in their buckets most of the time. This gives them a good capacity for additional stress events before they reach their threshold. Even if the dog were to wake up with their bucket completely empty, they then have their breakfast (+1L) and have a play with their owner (+1L = 2L in bucket). They then have a sniff in the garden (-1L = 1L in bucket). The owner takes the dog for a walk and they see a cat (+2L) then a tractor (+2L = 5L in bucket). This is still fine; they can cope with all of this.

Get home from walk and have an enrichment activity whilst owner is busy (-1L = 4L in bucket).

However, then a workman comes to the house (+3L = 7L in bucket), closely followed by the postman with a parcel (+2L = 9L in bucket). We are now very close to threshold, but dog still hasn’t gone over threshold, so owner isn’t aware, as they don’t know about trigger stacking.

They head out on their afternoon walk and it is a nice sniffy walk (-1L = 8L in bucket), but then at the end of the walk they see another dog, who barks at them as they approach (+3L = 11L in bucket!!). Oh dear, our dog barks, lunges and is pulling on the end of the lead.

Our poor owner is shocked and mortified and says the common ‘I’m so sorry, he never usually reacts like this’. However, both dogs were on leads so no real harm done. Both owners move on. Our owner wonders if it was something about the other dog that triggered them, as they are usually fine with other dogs, although a bit more wary if the other dog barks.

No! It was Trigger Stacking. Those events over this past day have overflowed our dog’s bucket. This same scenario could have played out over the space of three days with the same result (although likely more water out activities).

Trigger stacking | Meadow Family Rescue

Obviously, if you have a dog that is reactive to several triggers anyway, they will have a much fuller bucket in general and reach their threshold much quicker. This is why we recommend at least three days off after a stress event, to really ensure that bucket is fully empty before we expose our dogs to more stressors.