Helping me to make my dogs get along?

He is probably jealous. Give the big guy a lot of attention when the puppy is around.

What is the gender of the boxer?

Make sure you give them the same amount of attention and your time. A new puppy will always cause a little bit of jealousy. Make sure your older dog knows you still care and that he is not forgotten.

Can you seperate them? If you can, put them in seperate areas with a dog gate between them so they can see and smell each other but not get to each other.

Once they get used to each other you can remove the gate. When you are able to monitor them, you can leave the gate open. Close it when you don’t want to monitor them. Try to spend an equal amount of time on both sides of the gate.

Dogs are defined by their status.

Have a favourite: It goes against everything you probably know, but the younger puppy is junior to the older one, and the problems are caused by the amount of attention you give it.

depending on the breed the young pup can come off like a pain with all their jumping and nipping (playing), the older dog, if that’s whats happening. Its hard not to want to adore a new pup all the time. The senior of the two wants to be top dog too. I bet after some time they will become buds.

In a mix of dogs, one dog is alway the Alpha dog or leader. when his authority is challenged, a dog fight normally ensues. your older St. Bernard feels threatened by your new boxer puppy. if they both are the same sex, this is another problem. play with both dogs at the same time. use a new toy that neither dog has used before. dogs are very territorial, even with their toys. hope this works. john

You haven’t given the gender of the puppy nor have you really described the behavior of your younger dog and how the older dog reacts. You could be describing the older dog keeping the younger one in check OR about to kill the puppy . . . it is impossible to comment without more information.