My miniature foxies behaviour with big dogs

Question
My mini foxie - Maggie - is around 3 and a half years old. I walk her along the creek trail which leads to a local park. Often dogs are walked off their leads (I walk Maggie off her lead too for the most part).

I have become concerned though, as her behaviour with big dogs over the last few months has changed. If a big dog (that is off its lead) goes right up to her, she begins to bark in a fully aggressive manner at it, looking as though she is going to nip it.

This really scares me though, as I feel like my dog's behaviour may provoke the big dog into biting or attacking her (even if it wasn't initially planning to do this). I know that I become extremely tense now upon seeing a big dog approach, and will even modify our route sometimes, so that we don't directly pass the big dog. I think my fear has definitely increased since I've become pregnant. I'm 5 months pregnant and just don't know what I'd do if Maggie ended up in a fight with a big dog, and feel like I'd be an absolute mess if she was ever seriously injured.

Is there any advice you can give me??

Thanks Vanessa

Answer
The best way to correct this if you know someone with a big dog is to go to the park with both dogs,and muzzle yours,as well as the other dog,so your dog can get used to bigger dogs,without getting hurt or starting a fight,try this for a few weeks and she should improve