A lot of times dogs also mount as a way to initiate play. Most B's hate water and you can use a squirt bottle to get their attention, and possibly stop their mounting. One of my alpha females (until she was recently spayed) used to run around and mount all of my male dogs, she would even follow my service dog around and attempt to mount him when she was in season. Now that was a site! A Basenji trying to mount the head of a Thai Ridgeback. Bruiser would just look at me w/his pleading eyes saying "please help me MOM!" as soon as she was spayed (or came out of season) she would quit. I think she just wanted them to know she was (and still is) boss.
