When we started training our cat Roxy to be able to walk outside on a harness and leash we occasionally came across situations that she’d been exposed to before which caused her to have a meltdown and get totally stressed out. It was difficult to witness as we only wanted her to have positive experiences and join us in our love of the outdoors.

I had a breakthrough when I learned about trigger stacking which is when a dog or cat experiences multiple stressful events (positive or negative) in a short amount of time, without time to calm down between each event. This can lead to increased excitement, anxiety or aggression. 

A situation that on its own would be fine could result in a heightened emotional outcome for her if it was paired with one or more emotionally heightened situations - trigger stacking.