I agree with what Winner said, a secondary character staying on screen will definitely help with the direction of the acting. Just make sure to make the second character not so noticeable, and just react to the first one mostly.
Chris, yes I think you got what I was trying to say Just think about what the dog is feeling when he is transitioning, and instead of snapping from one pose to another, have your main poses be the strong “hit” poses and have him get there by subtle gestures (or even strong ones if there’s a place for it, you just don’t want to overshadow your main poses). For example, maybe before he says the big “SHEESH!” he could have more arc and follow through on his arms, head and back, and have them anticipate the drop into the “SHEESH” pose and then settle in…just an idea.
Good luck, I’d like to see your progress!