The Wicker Dog Bed is a furniture item in Nintendogs + Cats that can be bought from Modo Home in all versions for $30. It can be placed in one of the four corners of your home, and pets will sleep on it.
In Toy Poodle & New Friends, it is readily available.
In French Bulldog & New Friends, it must be unlocked with 2,600 Owner Points or by playing 13 days.
In Golden Retriever & New Friends, it must be unlocked with 450 Owner Points or by playing 4 days.
3DS: "This wicker dog bed is nice and airy for those hot days."