Dogs takes a little longer to unlock because you need to earn 500 Animal Degree points before Mirabelle gives you one. You can earn Animal Degree points by doing a variety of animal-related tasks, ranging from +1 point up to +1000 points per task. Dogs has two color of choices. They are dark brown and light brown. Just like other pets, you cannot swap dogs after choosing the one you like the pets. The color of dog you don't choose will be sent to live with Slater on Verdure Island. Each heart of friendship you earn with the miner will increase the number of dogs he has by one.