
Personally I'd leave them to it. Your dogs need to learn to communicate with each other.
If you are going to step in to stop the behaviour are you also going to keep them seperated when you are not about? If not, the youngster may only learn that he must stop the behaviour when you are there to enforce the rule (ie. how can you enforce the rule when your not there).
Sadly, my older dog died before Buster hit the teenage phase so the only issue betwen them was pup wanting to play and older dog not wanting to. I kept stopping pup from trying to play with the older dog as the odler dog just never told him off and it was obvious he wasn't happy to be pestered (
being a giant breed, Buster was as big as the adult dog as a pup, so could play VERY rough
). All that I achieved by my inteferance was that niether pup nor adult leant anything other than
I'd stop things - therfore I couldn't possibly leave them unatended together
(for fear of poor oldie getting completely bullied in my absence
). I thought the day would never come when they could be left alone together.
I stopped getting invloved, sure enough, oldie found his voice and told pup off, from then on the relathionship between them got better & better - they could communicate with each other! It was so much better not having to keep them supervised/seperate all the time.
> I seem to remember this happening before between the now older boy and an even older neutered boy, but he was much more bossy and told him off straight away.
Was you then older boy, older than 2.5 years (the age of your current older dog)? Perhaps it wasn't a case of bossyness, just maturity/confidance?