New Dog/Old Dog

Question
Hi,
I had two dogs that got along fine. One was very old and recently passed away from cancer. Charlie, the one left, was always very easy going and playful and so after awhile we decided to add an opposite sex spayed female to the mix. Candy is very sweet calm and playful. Charlie always loved to play so we thought a puppy would be a good fit. Unfortunately, he has turned into a different dog and aggressively attacks our 4 month old puppy, while she lays on the ground in submission yelping. I have read all the books on introducing new dogs and thought I was doing everything right but he just seems to be horrified by her presence in our home. Could this just not be a good fit or is there something else we could be doing to make it work out? Should we give it more time, I thought by now he would have come to like her. We have had Candy for a month and can not imagine giving her up. Any thoughts you may have on this are greatly appreciated. (Because of whats been happening, they are never alone together and I break up his fighting as quick as possible, so she won't get hurt)

Answer
Dear Aileen,

Your dog most likly thinks you either replacing you last dog or him. Also he wants her to know he's the alpha, and sometimes dog's will show great agression toward other dogs to show them that. What you should do is have them in the same room with you sitting between them. pet the both of them, and treat them equally. I've never hd this type of problem before, so i really cant giveyou alot of information, I think you should see a professional trainer or a vet, and see what they have to say. Please tell me how it goes, I hope that you dont have to give up either of the dogs, and that it all works out.
Amy