I have a 5 year old female collie mix and we just got a 4 month old whippet mix and the 5 year old female is humping my 4 month old male. this is kinda horrid cause she does it no matter where we go could be on a walk, just out side, inside , middle of the night... i am sick of it she is being stupid imo. ready to just get rid of her. and trust me raiseing 60 some sled dogs and i never had this issue. I even put a E-collar on her and every time i catch her i zap her she got to the point now where if she see's me she doesnt do it but soon as get out of sight she does it i had to put up mirrors all over to keep an eye on her so if i leave the room i have like 15 mirrors leading to where i am at. and if i see her mounting him i give her a hefty zap but its not working She is spayed he is not neutered yet. If there is a reason for this and if anyone has a clue i am willing to hear it. otherwise i am going to start thinking she is transexual or something... going to pawn her off soon tho if she doesnt get over this habbit