I know that it isn't everyone's interest, but I have discovered that pup play is a pretty exciting and releasing activity. I met with two guys know as Fossil9 from GearFetish and Recon and they are the players that really broke me into it. I had expressed an interest and they had been excited to play with me so we did some of it. I loved it and have looked at many pics on the internet like the few below that get me pretty horny when I think about it.
I'm not sure if it is the whole not being human thing, or that is just seems like a "slave" should not be anything but a dog. Don't get me wrong, I enjoy being a human being and don't wish I could become a dog, a puppy, or whatever permanently...and I most certainly DO NOT want to have sex with animals!
It is just fun to be a pup and play around I guess.