I think you have to allow for an adjustment period. Our pup is almost 3 months old and I have a 10 yr old Eskimo who is either pissed off at me or maybe a bit depressed, she won't leave my couch and is acting depressed, I know its due to the new puppy. I also have two chihuahuas, the one I was most worried about seems to be the only one that will play with the puppy, the other one I don't think likes her unless its meal time, then she is her best friend but only because she wants her to share some of her food. Its all an adjustment, as long as your older dog is still eating then its ok, they will probably adjust and be ok, atleast thats why my vet told me, its when they get so depressed that they stop eating that you can have problems. I'm going through the exact same thing as you times three with my three other dogs so I know its a process, I guess we all just have to be a little patient. Good luck to you.