Andy B wrote: she plays first
This would be the bit that would annoy me if I was walking my dog though. I'm not meaning this as a personal assault on yourself, it's just my opinion that dogs should be under control at all times. Put it this way - if all your dog did was run up and try and play with another random dog, then the other random dog seriously injured your dog - whos fault is that?
Is it the other dogs fault because it caused the harm? Is it you dogs fault because it was antagonising a random dog? Is it the owner of the other dogs fault cos they haven't been keeping control of their dog? Or is it yours because of the same?
The answer probably lies somewhere in the middle, but at the end of the day - your dog is seriously injured. Look at it from the other point of view - if its your dog that injures another - how would that make you feel? And what if your dog is blamed for it - that might not have the happiest outcome for her.
Aside from all that - if there is a noticable change in behaviour, you should take her to the vet and make sure all is well. Maybe she is drinking too much coca-cola... it makes kids hyper, it might do the same to dogs?*
*I do not endorse feeding soft drinks to any animals. Except Yudsters.