My first concern would be if the dog was up-to-date on shots(rabies). Friendships aside you must be sure you're not in danger. Ask for proof of vaccination. If this can't be offered then you must report the bite for your own safety. If the dog is up-to-date on shots then I would leave up to you as to what you do. If you have any medical expenses, they should pay them.
You must find out if the dog had a current rabies shot! See the proof!