I have a 14 month old shitzu that I rescued from an Amish puppy ill at 7 weeks with 3 broken legs. I nursed the puppy back to health and he has been the sweetest dog until approx. 1 month ago. My dog has been growling, snapping and very aggressive at times. There are other times when I can pick him up and play and snuggle with returned affection. I have a 3 year old female hound that he has been raised with and gets along well with. I also have a 4 year old male pit bull that he was raised with the first 7 months of his life. The pit and hound are fixed the Shitzu is not. the shitzu began growling at me and my husband and visitors and the pit bull jumped on him. We have kept the dogs separated by gates since this happened. The shitzu is sched to be neutered tomorrow. What is your recommendation?