May belongs to me: http://www.mangago.zone/read-manga/may_belongs_to_me/
http://www.mangago.zone/read-manga/kaihatsu_muramura_mode/
In chapter 5 there is some animal play.
http://www.mangago.zone/read-manga/lovely_play/
There's some sorta pet play in this one... kinda... lol
http://www.mangago.zone/read-manga/blood_bank/?av=1
Blood Bank had quite a bit of collar/restraint play in it (at least in the first half of the story). But it's for BDSM and not pet play.
Are you looking strictly for pet play [between humans]? or are you also interested in yaoi animal-people stories? (I know 'Ookami-san to Eroi koto' already kind of strayed into animal-people territory, but one of the ukes wears a collar so I counted it (≧ڡ≦)) If so, I have more where that came from and if not... well that's about all I have on my list ╮( ̄▽ ̄)╭ If we were talking about novels I would be able to recommend even more. Happy reading! (●'◡'●)ノ
http://www.mangago.zone/read-manga/welcome_to_the_caf_of_love/
I hadn't realized 'Welcome to the Cafe of Love' was available on Mangago, so here is one more.
Again, it's not exactly pet play nor is the uke human, but he's always wearing a collar (๑•ㅂ•)و✧
Does anyone know yaoi mangas were the seme or the uke wears a collar. (not omegaverse please) Like any animal or pet play type of situations?