I have an older dog his name is Harley. When Moses first arrived Harley took an instant dislike to him Moses puppy and a Belgian Malinois very energetic. It took being with them both and supervising when possible unable to do that 24/7 Harley would reprimand Moses in fact he caused a very big open sore on Moses nose Harley bit him hard. It took many walks and many being together with both boys and handling like brothers after about one month or so all good now. Do not separate them this is only going to cause more distance between both. It is important to allow them to work it out on their own and with help from family. The male is Alpha has been for long time now he has become territorial that is expected. Hang in there. I am only a junior member but I found this out by trial and error and allowed things to happen now both sleep together and Harley bathes Moses ears they even kiss. I hope this helps.