Toy dog usually refers to a very little dog or a grouping of miniature and very small breeds of dog. A toy dog may be of a variety of dog types. Types of dogs referred to as toy dogs may include Maltese, Chihuahua and Terriers that have been bred down in size. Not all toy dogs are lapdogs, although that is an important and ancient type of toy dog. The very smallest toy dogs are sometimes called teacup size, even though no major dog registry recognizes that term.
Dogs referred to as toy dogs and dogs found in the toy group of breed registries, may be of the very ancient lapdog type, or they may be small versions of hunting dogs or working dogs, bred down in size for a particular kind of work or to create a pet of suitable size. In the past, very small dogs not used for hunting were kept as symbols of prosperity, as watchdogs, and for the very important health function of attracting fleas away from their owners.