Your puppy is doing this because she is afraid of other dogs. Here are some things that may help:

1. Desensitise her to other dogs:
Start this in a quite place, e.g. a large school field after all the students have gone home. Get a friend to bring their dog. Stand far away from their dog and start walking towards them. While walking towards them, praise and treat your dog well if she is not showing any aggressive behaviors. Once she starts getting stressed, stop and move back until she gives you her attention again. Stop there and do some obedience commands with her. Let her sit and watch the other dog if she wants to, but get her attention every few seconds and treat her.

Once she is comfortable with this, you can reduce the distance. Reduce the distance slowly so that you do not spook her. When you see her getting stressed again, move back and restart. Keep sessions short and end on a positive note.

2. Be calm and assertive.
Dogs are very sensitive to what their human is feeling. My dog picks up on what I'm feeling and reflects it, with a hundred times more intensity. Even though you may be worried that your dog may react to another dog, if is important to stay calm and assertive. Make sure you do not put continous tension on the leash.

3. Ignore, Ignore, Ignore - Teach your dog avoidance.
When you see another dog, just ignore it and move along. I have found that avoidance is most effective when **I** ignore the other dog and owner as well, i.e. no eye contact. Just say a quick hi and move on, this shows your dog that nothing happens when other dogs come along so he shouldn't get stressed. Only start greeting again, once your dog does well with (1)

4. Use positive interrupts and keep encounters short.
If you are greeting another dog, you want to positively interrupt your dog every so often and make her refocus on you. Positively interrupt him many times if necessary so that she does not lose control of herself.. Whenever my dog is meeting a new dog I interrupt her after a very short duration (2-3 seconds).

Hope this helps.

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  awhhhhhhhhhh

for sure! where abouts you walk? ...