Wow! Thank you for the super fast responses.

Xena was aggressive with other dogs as well (not just the smaller ones). Before, she would lunge at other dogs in any opportunities. I guess the training helped her a bit. Now, she would only lunge at those dogs that are rude (running towards her and barking) to her.

But then again, the other day there was an off-leash pitbull approaching us slowly. They sniffed around for a bit, before Xena bit his genital . Nonetheless, the pitbull ran away. The only challenge with her now is that she doesn't give out any warnings before biting (no growling, barking, showing teeth or whatever).

We wanted her to be able to go to the Dog park and run around with other dogs. But until she is not snappy with smaller dogs, it's not going to happen.