Personalized Happy Birthday with Dog and Mouse Toddler Long Sleeve T-Shirt. Dog and Mouse are excited to wish you the happiest of birthdays! Happy Birthday with Dog and Mouse Toddler Long Sleeve Tee - White, perfect for those who love this friendly duo from "Dog and Mouse" by Michelle Nelson-Schmidt. A classic for Fall, Winter and Spring, these long sleeve toddler t-shirts are sure to be a staple in your child's wardrobe. Whether layered or alone, this t-shirt is soft yet durable enough to stand up to your toddler's playtime demands.