About food for the Shih-tzu are already quite a few articles written and there are very many types of food for sale. Chunks to fresh and frozen. We were often guided by the opinions of veterinarians, pet stores, dog owners. breeders where we brought a puppy etc. 
After many tried and after a lot of searching on the internet ect. We came to the conclusion that at first the dog and so also a Shih-tzu is a carnivore and secondly, every dog reacts differently to a particular food. So look well what for your doggy works best. Grain and rice can e.g. cause irritation and itching. We found to our surprise that our dog's didn't react good at all on a featured expensive brand and got a dull coat and even hair loss. When we switched on more fresh raw meat and another brand, she  looked healthier. Her coat was shinning again and the hair loss stopped. When we also gave salmon oil it only was getting better. They also got more energy. I went me even more and found out that it actually also quite logical. Centuries old is the dog a meat eater, in nature he consumed his meal also raw and he's also completely on built, to make sure your dog the very best nutrients and amino acids in balance gets inside, it is so raw and natural as possible give. Here on the menu is always, raw egg, in its entirety. Pancake with salmon oil, fresh meat,organ meats, meaty bones, alternating with KVV ready fresh meat, that is ground meat, organ meats and ground bones where all natural nutrients still in it. Some brands even have no added cereals you can get some try so to see what brand your dog likes the best . For example, Duck, Carnibest, Haaksbarf, Barf Naturis, Alaska, of course, complemented by a lump. Please pay attention that you give  always raw bones. Never fried, smoked, grilled or cooked. This process changes the structure of the bones and this can result in perforation of the intestines and stomach. !! Look good that you the bones not too small. Especially if your dog is a fast eater  as our Banjo then there is danger to choke. 
It is also very important to know what your dog is absolutely forbidden. n. l 
Chocolate contains Theobromine, and is extremely toxic to a dog.
Onion, leek, tomato, grape (and therefore also dried grapes).
Macadamia nuts kernels, apricots, almonds, Apple, avacado's, contain hydrocyanic acid and if they get a lot of it toxic to a dog
.Raw pork never carry this is very risky because it can contain Aujesky's disease. If a dog or cat this disease gets inside there is no salvation possible and they sure to death.!! 
No abundance of garlic. We give a small amount to the dogs. In the form of sheep fat chocolates with garlic. It is well known that it is a good natural defense against fleas and ticks. And it keeps the coat shiny and healthy. But give strictly the recommended dose. This i. v. m anemia what it can cause. But garlic is definitely non-toxic. Care, of course, that there is always a water bowl with fresh water for your dog.
If you customize your puppy in the House, you might wonder how much he or she can eat and how often.
We give about 5-10% of the body weight of the puppy to.. An average, so 50-75 grams per kilogram of body weight. Distributed throughout the day in four, five servings. Especially the first weeks it is wise to take it easy. The bits get them as a snack. Not too much because the main food is the CDV. If 25 grams per kilo of weight puppy we about the half. You have a fast enough rhythm and do you know what your puppy needs. 
He grows too much to give less and he is of course more to lean. An energetic puppy needs more than a quiet puppy.
Below are guidelines for the conduct of CDV. The feed gives you in portions over the day.
Up to 4 months about 5% of the body weight.
Up to 7 months approximately 4% of body weight.
To 10 months about 3% of the body weight.
Puppy 10 + months about 2% of the body weight.
Adult dog about 2/3% of the body weight.
A puppy up to 3 months run 4 times a day.
A puppy under 6 months run 3 x a day.
A puppy to 12 months enter 2 x per day.