Trigger Stacking–“but he’s normally fine!”

Recently I found myself on a short road trip. During part of the trip I was driving on a bridge over a body of water.  This particular road actually has two bridges–the northbound bridge has three lanes, while the southbound bridget has two.  During certain times/days the northbound bridge changes traffic pattern to have 1 of the lanes going southbound (to accommodate influx of travelers).  Both bridges are very tall, parts of them are between 150ft and 200ft above the water surface, and the northbound bridge does not have the typical solid concrete side-walls but actually has steel “railing” like sidewalls (which allows you to see the water some 150+ft below).
During my trip, I hit the bridges during the hours where one lane on the northbound bridge becomes a southbound lane.  There is no physical barrier between the two directions and there isn’t any extra cushion of space between cars going 45mph+ (speed limit was 45 but I guess many cars were speeding).  I was a little bit disturbed at going the “wrong way” on the bridge and the GPS “lady” on my phone was REALLY unhappy with me and started repeating “turn around!” “turn around!” “turn around!” as if her life depended on it.  I didn’t want to take my hands off the wheel to turn off the sound of the GPS because there was little room for error while driving.  As I started driving further onto the bridge and the distance above the water increased, I could feel my heart start racing and pounding in my chest, my hands started getting sweaty, I gripped onto that steering wheel so tight my knuckles turned white, my jaw clenched shut, and my respiration rate increased significantly. I started chattering and frantically talking as I continued to drive (as if there was any place to stop) and eventually had to yell at my GPS lady as I thew my phone under some stuff to smother her ANNOYING calls for help.
I was pretty much in a panic for the 30 minutes it took to drive over the bridge (okay, it probably only took 4 or 5 minutes but it felt like forever).  Between the certain death to my left in the way of oncoming traffic speeding to me, the fact that I FELT like I was going the wrong way on a one way street, the certain death to the right of me in a 180ft plummet to the water below (I don’t have a fear of heights, I have a fear of falling from heights), and my panicing GPS lady, I was having a total and complete anxiety attack–to the point that I yelled at and tried to smother my poor GPS lady.
I drove across the bridge a few other times with different situations (sometimes as a passenger) and I was didn’t have any problems.  As a passenger going northbound when all the lanes were in the same direction I was fine, driving on the southbound bridge I was fine, driving on the northbound bridge when all the lanes going north was fine.  Truth be told, I was a little uncomfortable but I wasn’t affected by the stress in any real way.
The problem I ran into is a situation called “Trigger Stacking.”  Individually, the wrong-way, against the traffic, 150ft+ above the water, being able to see straight down to the water because of the ‘open’ side walls, and GPS lady yelling at me, would be no big deal.  I regularly encounter bridges that have changing traffic patterns to accommodate rush hour traffic and they do not bother me one bit (even when I’m on the ‘wrong side’ of a normally one-way street).  I’ve driven over many bridges that are very high above the water below and even some that had more open looking sidewalls. And like any GPS user, I have been yelled at to turn around, make a u-turn or otherwise quickly change my route to get back on rack without any stress.

When all of these minor stresses were added together they became one huge stress that caused me to have some serious anxiety issues (even thinking about it now I can feel my heart start to race).  The idea of trigger stacking is something we have to always be aware of when handling dogs.  Imagine a set of wine glasses, each glass has some wine in it representing the stress of a given stressor (my GPS lady, the height of the bridge, the wrong-way traffic, and the oncoming traffic pattern).  Individually, none of these stressors are concerning, they are easily contained within the wine glasses.  However when we start pouring all of the stressors (the wine) into a single glass and adding them up, it ends in a horrible disaster, spilled wine.  In my case it resulted in an anxiety attack but with dogs it could lead to a bite, destructive behavior, anxious behaviors, reactive behaviors, or others depending on the situation.
When multiple stressors are combined, it’s easy for the dog’s wine glass to overflow and him start reacting to things that “he’s normally fine with.”  It’s not that he’s “not fine” with that particular thing but that all the other stressors in the situation have made his glass overflow and he can’t handle all the stress.

It’s something I see a lot of actually and while it normally doesn’t end in total disaster, it absolutely could in many situations.  I was at a large outdoor doggie event a few summers ago. The day was quite hot and humid and there was a medium sized beagle mix dog who I had seen walking around for about an hour.  I had seen the pup greet a bunch of dogs on leash earlier in the day but after an hour, or so I started seeing the pup getting snarky with dogs in his space. The owner was getting mad at the dog and start leash popping the pup repeatedly for his growls (yet continued to let him go say hi to other dogs).  At one point, the dog was greeting another dog and really snarked at the dog–I don’t know for sure but I’m guessing he made some sort of contact with the dog because the other dog yelped and jumped away. When his owner bent down to scold him, he air snapped at her.  She was shocked and really offended by her dog’s behavior (and probably a bit scared) and she finally left with him in tow, slinking behind her with his tail tucked, ears really down and head low hung.
Was the beagle mix unfriendly or aggressive?  I doubt it.  His behavior was likely the result of trigger stacking.  Between the stress of being at a huge and loud doggie event, the heat of the day, the length of the visit, the many doggie greetings, and being tired, he started becoming not ‘okay’ with things that he is normally fine with (greeting other dogs and even snapping at his mom).
It’s something handlers really need to remember–if there are multiple stressors involved, the dog may not act in the way he normally does and that can be a dangerous situation.  This is even more prominent for fearful dogs, anxious dogs, or dog that already have some behavior problems.