The Fireman's Hat is an item from Nintendogs. It is a red hat with the words "Fire Chief" on the front. In Nintendogs: Dalmatian and Friends it is a starter Accessory item that sells for $30 at the Secondhand Shop, which also comes with the Dalmatian as one of the starter breeds. In other versions of Nintendogs it can be found on walks, and if you find it, it unlocks the Dalmatian breed. The Dalmatian breed in any version of the Nintendogs + Cats series can be unlocked without getting this hat.
DS: "Wearing this hat makes your pup feel like a friendly neighbourhood fireman."