How big are Shih Tzus?

The traditional size for the Shih Tzu is 8-11 inches at the shoulder and 9-16 pounds, but some individuals are smaller, in the 5-9 pound range.
Have you heard these phrases: Imperial Shih Tzu? Teacup Shih Tzu? Tiny Toy Shih Tzu? Miniature Shih Tzu? Some breeders use these cutesy, made-up phrases as "marketing terms" for smaller Shih Tzu. That's all they are -- marketing terms. There is only one Shih Tzu breed, and whether an individual weighs 5 pounds or 15 pounds, he's still just a Shih Tzu. Some are simply smaller or larger than others. The larger individuals are sturdier and make safer pets for many families.

Where does the Shih Tzu come from, and why was the breed developed?
The Shih Tzu was developed in China (possibly Tibet), as a lapdog companion for Chinese royalty.

How is Shih Tzu pronounced, and what does it mean?
The Chinese pronunciation is roughly SHIRR dza, but the Western pronunciation is SHEET-sue. The name means Lion Dog and refers to the "regal look" of the breed.
The nickname Chrysanthemum Dog is sometimes applied to the breed, as well

What colors do Shih Tzus come in?
Shih Tzus can be any color: solid, particolor, and blends. Usually they have a white blaze on their face.

Do Shih Tzus come in longhaired and shorthaired varieties?
No, their natural coat is always longhaired, silky, and dense, and it's a double coat (which means an outer coat, plus an insulating undercoat).
Many owners choose to minimize brushing and keep their Shih Tzu looking like a perpetual puppy (very cute!) by shearing (clipping) the coat short several times a year. You can do this yourself, or have a professional groomer do it.

Are there any health concerns with their short face, or their short-legged, long-backed build?
Yes. Some Shih Tzus are more "normal-looking" than others. More normal-looking Shih Tzus have a face (muzzle) that is a little longer, legs that are a little longer and straighter, a body that is a little shorter, and/or eyes that are smaller and less protruding.
Other Shih Tzus have a very squashed face, large protruding eyes, stubby bowed legs, and/or a very long body.
The more "normal-looking" a Shih Tzu is . . . the better.
The Shih Tzu can be a great little dog, but the reality is that his physical build is neither natural or healthy. The Shih Tzu, in fact, is afflicted with two skeletal deformities: chondrodysplasia and brachycephalic syndrome.

Chondrodysplasia
Dogs were never intended to have a long back and short legs, especially if the legs are bowed (like Queen Anne furniture legs). This build is caused by a genetic skeletal deformity called chondrodysplasia, which translates roughly to faulty cartilage.
When a puppy is developing in the womb, his skeleton is first formed in cartilage as a sort of model. As he continues to develop, the cartilage is supposed to be replaced by bone. But if, because of certain inherited genes, the cartilage doesn't get enough blood to transform properly into normal bone, the puppy will be born with incorrect proportions of cartilage and bone. The result is a large head and chest, short, thick, bowed front legs, and a longish back with calcified disks that lack elasticity and cushioning powers and are predisposed to coming loose and protruding into the spinal canal (intervertebral disk disease). Chondrodysplastic dogs are also more susceptible to joint problems, and later in life, arthritis.

Brachycephalic (BRAK-ah-sa-FAL-ik) syndrome
This tongue twisting word comes from the Greek roots brachy (meaning short) and cephalic (meaning head). A rounded head and shortened face are skeletal deformities that cause a variety of health problems.
•    All short-faced dogs have some trouble breathing. They snuffle and snort their way through life, with their breathing difficulties becoming worse when they're excited.
•    Their nostrils tend to be slim and pinched and may have soft cartilage that cause the nostrils to collapse when the dog tries to pull air in forcefully.
•    The trachea (windpipe) tends to be narrow, restricting air flow even more.
•    The soft palate (a flap of skin across the back of the throat that prevents food and water from entering the windpipe) is often fleshy and elongated and tends to fall loosely into the throat. This causes noisy breathing, gagging and hacking (as though the dog has mucous in his throat), and sometimes spitting up white froth.
•    The eye sockets are shallow, which means the eyes could actually pop out if the dog bangs his head while playing or even pulls too hard on the leash.
•    The prominent eyeball is susceptible to scratches and corneal ulcers.
•    If the eyelid can't reach out far enough to fully cover the protruding eyeball, the eye can dry out, leading to a serious disorder called, appropriately, dry eye.
•    The teeth are crowded together and tend to grow at odd angles, trapping food debris and leading to dental disease.
•    Their loose folds of facial skin are dark, warm, and moist -- perfect breeding grounds for bacteria. The result can be raw irritated skin and chronic bacterial infections called pyoderma (skin fold dermatitis).
•    Eating and drinking can cause problems because when they put their face into a bowl and try to coordinate swallowing and breathing, food particles and water can get pulled through their nose and into their windpipe, causing gagging, coughing, or spitting up.
•    On a more delicate note, breathing through the mouth means swallowing air, which often produces excessive gas.
•    Short-faced dogs frequently can't deliver their puppies because the puppies have such large rounded heads. C-sections under general anesthesia are typically required, and short-faced puppies are exceptionally fragile and have a higher mortality rate than puppies with normal heads.
•    Short-faced dogs are risky to anesthetize, requiring extra-special precautions for neutering, dental cleaning, and x-rays.
Brachycephalic syndrome isn't a disease that your Shih Tzu "might get." It's a syndrome that ALL short-faced dogs are born with. Their respiratory system is structurally compromised, and they all suffer some degree of associated health problems.

That's why, from a health perspective, the more normal-looking your Shih Tzu is . . . the better.

Some things you can do to help your Shih Tzu:
•    Keep him slim. Extra weight means that he has to breathe harder to carry it around.
•    Wash and dry his face after every meal or long drink of water.
•    In hot or humid weather, keep him in an air-conditioned home as much as possible.
•    When he goes outside in hot or humid weather, don't let him get over-excited or over-active. Short-faced dogs have a high risk of heatstroke because they can't pant vigorously enough to lower their body heat.
•    NEVER leave him alone in a car. Even if it doesn't seem particularly warm outside to you, and even with the windows rolled down part-way, heat and stuffiness can build up rapidly and a short-faced dog can die.
•    Teach him not to pull on the leash, or else walk him with a harness. A collar puts pressure on his windpipe. Make sure the harness is shaped so that it wraps around his CHEST, not around his throat. A Y-shaped harness is what you want, not a figure-8-shaped harness.
•    Keep him away from chemicals that could irritate his respiratory system. This means no smoking in the house and no chemical cleaning products (buy natural cleaners from the health food store). Keep him away from freshly-cut grass, and indoors as much as possible during pollen season.
•    Make sure your vet uses only the most modern anesthetics (such as isoflurane). Insist on having his heart and breathing monitored by special equipment whenever he must go under anesthesia. Many vets are NOT careful enough with short-faced breeds.

Source: http://www.yourpurebredpuppy.com/