my only experience was in college when I let my dog (a miniature poodle!) fuck me a couple of times. we both enjoyed ourselves. I tried to fuck a friends bitch once, but it was too small and not cooperative. I tried to suck another friend's dog's dick, but he wasn't into it either. My brother has a bunch of miniature horses, and a couple of times when I've visited I've gone out in the field with his horses and several of the mares were interested, one even backed her pussy up onto my dick for me. but it was a little too high for me and it didn't quite work. but another time with a different mare ( I think) I did get my dick in her.