I have not had a personal experience with this. But I do have a boy who has been used by a dog. He was a bit freaked out about it... the dog licked him to high heaven (), but he didn't use his safeword until the woman wanted him to suck on the dog.

Funny... but he mentions this to me as if he would like to potentially explore it again.

I'd have no idea where to find a dog like that. lolol As I know dogs have to be specially trained into sexual service.