Posted: Tue May 7, 2019 8:08am
I am a Qualified Pet Behaviour Therapist here in the UK.
Some good advice from Phillip.
It is almost always lack of early socialisation and/or a bad experience. A really well socialised puppy will recover from a bad experience so it is vital that they see a variety of dogs, people and places during the critical period for socialisation. This is up to 12/14 weeks. After that time the nerves milienate and the dog will have fear periods from then on.
You can help your dog by muzzle training her so that she is comfortable wearing a basket style muzzle. Call it a new fashion accessory so that both you and the dog look upon with a positive view.
When out and about you will find that people will be more inclined to keep their dogs away which is what you want.
Every chance you get take her to a quiet place where she can see other dogs outside her critical distance. You will be able to measure that by how relaxed she is. If she is not relaxed move further away. Take some tasty treats and feed her every time she looks at another dog. Play games with her and generally fill her with positive emotions.
If you accidentally meet another dog - do not tighten the lead! This sends fear signals straight to her and makes her much, much worse. As soon as you see another dog change direction in a happy way and reward any good behaviour. Stay upbeat throughout. If you are stuck in an alley then get out your fabulous treats and feed her them one after the other until the dog has passed. This is called "bar open - bar closed" and is a good way of persuading a dog that good things happen when another dog is around.
Be very careful that your dog trainer uses positive methods. You could contact the local rescue to see if they know of kind trainers in your area.