Personalized I'm Four Years Old with Dog and Mouse Newborn Layette. Celebrate your birthday with Dog and Mouse, the unlikely best friends from the children's book "Dog and Mouse" by Michelle Nelson-Schmidt. I'm Four Years Old with Dog and Mouse Newborn Layette - Light Blue, perfect for young readers, helpers, and great friends on their birthday. 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