My dog's eyes dilate significantly when I play tug with him; he will also give me what looks like a whale eye (an anxiety signal) if I 'let' him win and won't take the tug toy back to continue.
His pupils don't change when I ask him to Sit or Down, but they don't afterwards, as if in anticipation for the cue.
His pupils don't change when I ask him to Sit or Down, but they don't afterwards, as if in anticipation for the cue.