@Maria16274 Intelligent and conscientious pet owners pick up after their animals, no matter where they are. No host should have to tell a guest to pick up their dog's poop. We don't have to tell them to flush a toilet, do we?
Let the guest know that you were fined for her dog poop and send her a Resolution Center request for reimbursement. It doesn't matter if she pays it or not. I would also put it in her review -- "An otherwise good guest who did not clean up after her pet."
I allow pets. My checkout instructions sent to the guest and posted on the kitchen wall state that the guest must pick up all pet debris in the yard. It is not in my house rules on AirBnB. Responsible pet owners KNOW to pick up after their pets.