There are a few things you can do to keep your dog clean during menstruation. First, you should have some absorbent pads or diapers on hand to put on her when she is in heat. This will help to catch any blood that may drip and prevent staining of furniture or clothing. Secondly, you should give her a bath more frequently than usual during this time. Use a mild shampoo and be sure to rinse all the soap out completely. Finally, keep an eye on her vulva area and wipe it clean as needed with a damp cloth.