Thanks to The Spotted Tongue blog, I am able to classify Dolce's reactivity as frustrated.
"1. Fear. Dogs that lack socialization often react to every little noise, every little thing they see. That tall guy in the hat? They've never seen something like that before, they get scared, and so lash out. Barking and lunging will make the scary thing go away! That dog who is easily twice their size? They've never met a dog that big, they get scared, and lash out at that. To the laymen it looks like aggression and while it's a form of aggression, the root cause of it is fear.
2. Frustration. Some dogs have little frustration tolerance and so when they see something they want to get to but can't (because they're on leash or behind a fence), they lash out in frustration. I liken it to a toddler throwing a temper tantrum. They lose all control of themselves and bark and lunge. It looks nearly the same as the fear response, but isn't.
The body language for the two is different, especially in the ear set (back for fear, forward for frustration) and tail set (down much further for a fearful dog)."
We made good progress again today with several close encounters on our hike, but were surprised by an Aussie shepherd from close behind and had an episode at the end. However, Dolce needed far fewer treats today, and has started working for a mix of treats and kibble. I am an avid fan of NILIF and it's very appealing to have Dolce happily work for nothing more than his breakfast. :)
Our proudest discovery of the day was when Dolce played, "Look, a dog!" with an oncoming dog without me standing between him an the other dog. We passed with nothing more than a split rail fence and some short shrubs between us and no great shakes multiple times. I'm a proud Mama. :)