
My friend has a golden retriever that she got at a year old. when I first met her she was 3 years old and hated other dogs, but was fascinated by my new puppy.
We introduced her to the pup, and then carefully to the mother who she did have a pop at a few times, but my girl just shrugged her shoulders.
I started taking her out with my two and off lead she was fine unless a dog sniffed her, but her general obedience was good, so it was easy to avoid such situations by advising the other dogs owners not to let their dog sniff at her.
She became very fast friends with my puppy and enjoyed rough housing with her and then the Mum, so learnt that dogs were fun.
Gradually I was able to encourage her to stay calm when greeting other dogs, I made the greetings short enough for her not to have time to get uncomfortable, so that she could be rewarded with praise and treats.
Eventually she became very dog savvy,a and didn't over react when she met dogs, got to play and enjoy their company, but could still tell off in a controlled and reasonable way any rude dog.
In other words she became a well adjusted canine.
It is important that during these socialisation times that the dogs they interact with are absolutely bomb proof and are the kind that will not react to his negative behaviour and will ignore it. the dog also learns to trust your judgement.