You can sue her for the amount of the vet bills. The following link will explain the procedure: http://www.supremecourt.ohio.gov/JCS/interpreterSvcs/forms/english/5.pdf
Every time you see the dog off its property without a leash, call the police or animal control.
If we do not have a signed fee agreement I am not your attorney and this is not legal advice.
The dog's owner is responsible for all the documented damages; that means all your vet bills, prescriptions, etc. This means you must keep accurate records of all those expenses.
You should have filed a complaint with animal control as well as the police. You will need copies of those reports.
As for suing the clearly indifferent and irresponsible owner, small claims court is the usual forum. It is designed to be "user-friendly" with simplified procedures.
Note that you state and county bar associations may have a dial a lawyer or lawyer of the day programs which can assist you.
However, the real issue is collecting. A dog owner as irresponsible as the one you describe is unlikely to have insurance and will likely have little regard for any judgment you may obtain in court. It is collecting the judgment that is always the difficult issue in these cases.
The foregoing is for general information purposes and does not establish an attorney-client relationship.