This issue has developed post-Covid, and seems to be getting worse. Before Covid, we lived in a big city and he was absolutely fine with meeting any other dogs on or off lead. We saw lots of different people and dogs every day, and often stopped to chat. During Covid, we were in an isolated location where we only saw the same few people and familiar dogs for a couple of years, usually off lead.
We've now moved back to a city and he's deeply unhappy about meeting other dogs on the lead - he whines when he spots them, pulls to try to get to them, and growls if they get anywhere near him. He's still fine off lead.
Any ideas about what I should do to combat this? Thank you!