I believe that you can teach an old dog new tricks so to speak. Some dogs will give a rambunctious pup a pass because it's a pup, but others don't. I've noticed that my oldest is much more lenient with my younger golden then with any other dog ever, I find it almost weird. I think once they get older it's harder but still can be done and carefully.
Misty- Samoyed Mix
Tannor- Golden Retriever CGC
Robyn- German Shepherd CGC, TC
Midnite-German Shepherd CGC, TC
Brennan- Golden Retriever CGC