Toy dog term teacup dog, thus the toy/teacup boundary remains fuzzy. The standard size for a toy dog ranges from 4 to 7 pounds; anything smaller than the standard size of a toy dog may be a runt of a litter. No official size defines a teacup dog, but unofficially a teacup dog is considered to be a dog that is 17 inches or less and weighs 4 lbs or less at the age of 12 months. There are no specific teacup dog breeds, but popular types for breeding teacup dogs include: Shih Tzu, Chihuahua, Yorkshire Terrier, Poodle, Pug, Maltese, Pomeranian, and
Mexican Hairless Dog breeds. A spacious, well-fenced, and safe physical environment is desirable for this breed. Daily walks are ideal for exercising most toy-sized Xolos, however more stimulating physical and mental exercise is advised for larger and more active individuals. Behavior problems in Xolos are typically a result of a dog receiving inadequate or inconsistent supervision, as well as inadequate exercise and mental stimulation. The Xoloitzcuintli is a social dog that should not, in most cases, be an "only dog". It does not do well when kept as an outside-only dog. This is a breed that is at its best when it is