you dog has a simple case of mixed emotions about the new situation of dogs.. He inst assosiated much you said? WEll that can be a factor on why he was acting trangly. He seen a female and he felt he must have nominace but submissed. He saw a male and he felt as he need to plat *finding out whos dominant* The male mounted the other male because of dominance, Male dogs do this often *EXspecaily when not altered* .. You should assosate your dog alot more with other dogs ok, So bad behavior such as having a domince problem and a prey drive dont accure. You dog was being aggresive when his hair was on end on the scruff of his neck. My dog does that when She is being aggresive and trying to get dominace. .. The drooling thing is normal. Did your dog haver his head on the other dogs back while he was drooling? Because if he did he was tying to get his sent more suductive over the other dogs body. email me at [email protected] if you have ANY dominace or aggresion Questions.. I have alot of books and crud..