The rather sexy image below is from Lady Pim who plays out of the Ritual Chamber in Toronto. She also has a short but informative thread on puppy play here.
I’ve never yet indulged in this kink, but it does make sense to me. It pushes buttons around giving up control, obedience, caring dominance, physical restraint, etc. Like a lot of BDSM dynamics, it allows the submissive to simplify his thinking, give up real world concerns and focus on the dominant and her instructions.