Hello madam good evening. You are not clear mentioned whether the scratch is by the teeth or by the Nail of the street dog. Please try to talk to me I will explain otherwise you try to consult any general physician at your local area and follow the suggestion given by the doctor and do not neglect. You can talk to me e i will definitely advice because if there is a chance in taking the medications it should be taken within 24 hours. Thank you very much.