We adopted a 5 year old male dog a few months ago. He has been nuetered for years, but he seems to very easily get excessively aroused by our spayed female dog. For example, if she happens to lay on her back, he will bolt over and start licking her genital area. He also does this if she tries to start playing with him. He will also keep trying to mount her and be thrusting his hips back and forth. I know that people say that mounting is a dominance thing, but I really don’t think that’s the case here. Especially since she is the dominant one of the two. When he does start to get on top of her, she gets annoyed and will start growling and he will back off, for a little while anyway. (We also are always telling him "no", and he will listen and get down, but he keeps going back) He also gets erections and will go lay somewhere by himself and lick/orally stimulate himself while bucking his hips. He does this everyday. At first we thought he might settle down after he got used to our other dog, but it hasn’t changed. Any ideas on why this could be happenung? I just feel that for a neutered dog, he seems to have a lot of hormones.