On the facts as stated, she shot YOUR dogs on YOUR property. Most, if not all, states have statutes permitting the killing of dogs off their property at attacking people and domestic animals. Therefore, even if MI has such a statute, it would not cover this incident.
Document ALL expenses thoroughly. When treatment is complete, compile all receipts, make copies of them and sent the COPIES with a demand letter by certified mail/return receipt requested.
Assuming payment is not made, you can bring an action in small claims court.
The MI and your county bar associations can provide referrals, if needed.
The foregoing is for general information purposes and does not establish an attorney-client relationship.
It sounds as though she may have been criminally charged, is that correct? Even if she were criminally charged and ordered to pay restitution, you can sue her in small claims court for the veterinary bills.
This is not to be construed as legal advice. I do not have an attorney client relationship with you.