the big ones with erections. They only spawn during wolf events to my knowledge. Easiest way to get one is to pass out in a pine forest during the day, which i find easily achieved by using the KYAH command from the map. Chance for a wolf event is lowish though, as you mostly run into undead or goblins with the roll from my luck.Which dogs/wolves can fuck you now? I tried looking around but I didn't find a single one what was juicable.
Juicing them is a huge pain as you need to stun them or use the move from stealth as otherwise you'll be interrupted. Also their orgasm is currently busted.