The AKC standard for a Shih Tzu is 9 - 16lbs. The Shih Tzu is not supposed to be a fragile dog. Correct Shih Tzu are sturdy little dogs with good bone
The terms “imperial,” "pocket puppy" and “tiny teacup” are sometimes used to describe undersized Shih Tzu. The proceeding terms are generally used by unethical breeders to drive up prices for dogs that do not conform to the standard. These breeders lure puppy buyers in by using these terms to make buyers think these puppies are unusual or special. Most certainly special or unusual Shih Tzu puppies bring a much higher price.
"Imperial" Shih Tzu breeders have purposely downsized, an already small dog, In the name of the mighty dollar. These breeders risk the overall health and wonderful distinguishing breed characteristics that responsible breeders have worked long and hard to preserve.
Read more about this subject at www.shihtzukisses.com/imperials.htm