The Milk Carton/Formula (Japanese: ミルク,"Miruku") is an item in Nintendogs and Nintendogs + Cats that falls under the category of "Care" in the Supplies. It is more expensive than a Water Bottle and considered more nutritious for the player's dog. Milk comes in a carton in the DS version, while Formula comes in a glass bottle in the 3DS version.
Nintendogs: "This milk is very easy on a dog's stomach. (One Serving)"
Nintendogs+ Cats: (NTSC): "This formula is specially prepared for growing puppies and kittens." (PAL): "This milk formula is specially prepared for puppies and kittens."