female dog dominance behavior

Is this the sexual behavior of a spayed female Staffie?

My Staffie little, like most Staffies, is a bit bossy lady and sometimes she * our dog mounting another. I used to assume this was the behavior of domination, but you know, it seems she is enjoying it. I will not go into detail and you can use your imagination, but it behaves the way it seems to me that you are having fun. Is this normal? She is now 8 and she has always been. Should I let her do it? It is something that occasionally, not every day or so. It does sometimes try a Staffie male friends and that only allowed! She seems to enjoy it, but she does not get aggressive or nasty with our dog, she just gets up and has a good time for a few seconds. I tried to stop her, however, simply because it can not be good for our dog another woman. She never tries any other dogs, and she never tried it with a person, thank God.

If she has been doing this all his life, 8 years, why stop now. I'm sure it's a little fun and enjoy the life is never over. As long as it does not make a practice of doing this with strange dogs what is the harm.

Puddin’ Pit Bull and her new dog friend