Well, now you're at the point to start paperwork to not renew her rental, since it's only 1 1/2 months off. That sounds like the best policy, and NEVER NEVER NEVER allow a dog (or any pet) if it's not in your original lease. I wonder how many people take advantage like this? I'll bet the number is staggering.
If you try to get a pet deposit out of her, would she even pay it, knowing that you're not going to renew her lease? Forcing her to get rid of all the pets is the best idea, but really, she needs to go, and that's a very good reason for getting her out. She's lost your trust.
I agree with the other poster, get back there and take lots of pictures, in case she tries to resist (and I expect she will).
I live rural, and sorry to all you pet chicken fans, but they do smell. Especially once it rains, ugh. And bring in flies, etc... It's highly unfair to the neighbor who's been true to her lease, and who is obviously unhappy about this.
Good luck!