Personalized Happy Birthday with Dog and Mouse Newborn Layette. Dog and Mouse are excited to wish you the happiest of birthdays! Happy Birthday with Dog and Mouse Newborn Layette - White, perfect for those who love this friendly duo from "Dog and Mouse" by Michelle Nelson-Schmidt. 100% combed ringspun cotton 5.8 ounce 1×1 baby rib sleeper. 3/8" flatlock binding at envelope neck and cuffs. Back sleeve flap to protect hands. Elastic opening at bottom. Infant: 0-3 Months