What can I do for this cat?

Our neighbor keeps this sweet cat outside and neglects it entirely. She refuses to give it up and our local animal services has not been helpful. This cat has fleas and I believe gum disease as she drools constantly. We have been feeding her since we moved in 6 months ago and she is now a healthy weight, but with the colder weather she has started to lose/rip out her fur. I have ordered flea medicine to hopefully solve the root cause but I am also wondering if I should get some sort of spray/cream to apply to her skin. Thank you.