I think this new Pet Play tag would involve a lot of the artworks with people wearing collars/leashes, but it shouldn't apply to characters where the "collar" is actually a choker that is a part of their canon outfit. (UNLESS the character's choker is being used as a collar in a sexual way)
The Pet Play tag would also involve scenarios where a character is wearing a sort of harness or muzzle (again, not Pet Play if the accessory is a part of their normal outfit.)
Now, scenarios where a character thinks another character looks like a cute animal may or may not belong under Pet Play, depending on the "vibes" of the artwork and how the scenario continues after that moment. So, a case by case basis. Similarly, not ALL Animal Ears artwork belongs under the Pet Play tag, but some of it may qualify depending on what the characters are thinking about each other. Pet Play often has a theme of "ownership" but its totally possible for there to be artworks of two or more "pets" doing Pet Play with each other, so artworks shouldn't be ruled out for there being no clear "owner"/dominant/or top. Thank you for considering this request! It's nice to have people hear me out.
[*snip*]
I second this, as there are many cute pictures that somehow fall under BDSM
under the current rules. So fwiw, I'm greatly in favour of it.
However, there are a two things I want to preemptively throw into the ring:
1.) How does this interact with the already existing Animalization
tag? Beware of Dog for example is tagged as such.
2.) What about collar+leash in "normal" bondage contexts, e. g. here (NSFW)? What about this (SFW)? Imho being liberal in what you accept, it is going to be easier on the mods who have to evaluate the tags to allow every kind of leash. (Well, except this one :P)
And to add my own list of examples (there about three dozen more depending on my second point), all SFW:
30814, 8685, 29431, 20482, 31372, 31401, 28931, 27150, 25544, 29359 and 11687 with an ensuing discussion about what is and isn't pet play.