Zak George "Scientific Consensus" Indeed. Lets Get Into AVSAB - Vet Behaviorists.

You cannot "train" a dog to behave - that's reality. That's not how behaviors work at all. Yet, nobody wants to define the word "behavior".

What is a behavior? It's your body's response to something in the environment. In the case of fight or flight - it's a chemical response. Cortisol and adrenaline and such. If a vet can't understand how cortisol creates a fight or flight response that is aggression and reactivity - then we have some serious issues.