So there’s a point when you’re scratching the back of a big ole dog and you hit that magic spot. The dogs skin shifts back and forth in order to stay in the perfect position to keep your undulating digits on the right position to provide tactile nirvana.
The back leg kicks intermittently when it’s not twitching in ecstasy.
Scratching a dogs back isn’t the only thing that generates this behavior though.
Wadding up a good length of a medium grit toilet paper so as to satiate that unbearable itch on the back forty of the gooch elicits the same physical reaction…..
So I’m told.