The American Kennel Club (AKC) does not recognize the teacup or mini Boston Terrier as a separate breed. International standards for the breed require a height of 15 to 17 inches and a weight of no more than 25 pounds.
The AKC classifies the Boston terrier as a small breed, not a toy breed. Like many purebred dog breeds, Boston terriers can sometimes be overbred. One result of this overbreeding is smaller dogs, which some breeders try to sell as teacup examples of the breed in order to sell dogs that are not eligible to be registered with the AKC. Smaller individuals may be prone to greater health problems.