Nipping it in the bud worked
This morning WD was waiting for me behind a gate (indoors). He started barking and jumping onto the gate as soon as he saw me (Yep, 10 months old male!) Without having to think about it I immediately turned around and disappeared into another room without looking or saying anything to him. I waited a few seconds after he was quiet and came back. He started barking and I repeated the same routine. All in all I had to do this three times. Before I walked through the gate, I put him in a down, then a sit and calmy greeted him and then ignoring him again. Never had to scold or correct him, which would only have made matters worse. For him to be left alone was the worse that could have happened to him but I still consider it gentle. And he understood.
Deja, GSD, sable WL, female, born 11 / 2013
Cam, Rough Collie, sable, male, born 8/2015