iggy:
Some dogs have a natural prey instinct which drives them to go after other animals such as cats or smaller dogs. It sounds like she might have that instinct. Unfortunately, it's really tough to train it out of them, but it can be done. My ex and I had a dog that was like that. It took a few years, but she eventually stopped chasing the cat. And dogs LOVE used tampons and pads. I had a dog in high school that would dig out my used lady products from the garbage so much that I had to put the garbage can on top of the toilet because used sanitary products can be deadly if they get lodged in their intestines. Fun fact, the same dog that loved my used period products also loved to eat my underwear. It was gross. 
grumpyemt:
Sorry the dog is not responding. Maybe try a dog whistle? Or training collar. Those are the only things that worked for a friend training his dog not to attack the cat.
punkinhead:
@iggy Bobbi is also an "underwear fan." She actually chewed up two pairs so far . . . And she also has that chase instinct that you mentioned - she goes after squirrels, like all dogs, but also after any birds she sees, which I have never seen in a dog before. I will say that we have had some very big strides this week, and Bobbi is getting much better at ignoring the cat. I am feeling hopeful about this for the first time!