We have a 6 year old Jack Russel/Corgi cross who is the nicest, most placid dog ever. We decided to get a puppy a few months ago, he is a five month old german shepherd. We got him from the RSPCA and so took our dog to meet him before we took him home, they got on fine. However, since bringing him home they haven't got on at all. The pup jumps on the jack russel all the time, which was fine by the jack russel when the pup was small but now he is 2.5 times his size. He growls at him to tell him to get off and the german shepherd barks at him, they cannot be in the same room together without being at each other. When we go out for a walk, one person cannot walk them together as the pup jumps on the other dog constantly and they fight. We have a 4.5 year old and she has almost been caught of the middle of them a couple of times, I am also 6.5 months pregnant and have been knocked over by them whilst they've been fighting and obviously it is far from ideal for the situation to continue once the baby is born. We really don't want to get rid of the pup as he is lovely but the current situation is dangerous. Does anyone have any advice?