Our 4½ year old boxer (rescued at 16 months old) has started lunging & pulling to get to other dogs. She has always been excited when seeing other dogs but nowadays I have to stop the pushchair (have a 3 month old) & get Sasha to sit. Her bum will hover over the ground until the dog gets near then she'll lunge. Sometimes her hackles are up & if she gets close enough there can be a noisy scuffle. I'm no expert (first dog!) but it seems to me she's trying to protect us as it's only really become a problem since the baby came along.
She did get attacked by a German shepherd a few times last year and since then has been wary of other dogs rather than her usual bouncy playful self. Sue would occasionally have a warning scuffle with a dog after this but now she's funny with every dog.
She is fine with people apart from occasionally jumping up with excitement.
Sorry for long post but if anyone has any tips I'd be very grateful. I'm concerned about this behaviour carrying on and dd getting in the way when she's older.