Always make sure your puppy has fresh water and fresh food in front of him at all times. He is a growing puppy and needs nourishment available to him at his choosing.
Shih Tzu have a very fluffy and full coat. Consequently, they may appear well fed even if they're not. Feel your puppy's body to make sure it is not too thin. Watch your puppy to make sure it is eating a good amount of food daily.
If your puppy appears thin, add some canned food, we recommend Purina Pro Plan Focus (chicken & rice), to his daily food plan. Puppies under stress may not be eating all they need. The less they eat, the less they want, until they are in danger and not wanting to eat at all. They can then go into hypoglycemic shock from lack of food (deficiency of glucose in the bloodstream).
Activity is also a good indicator of your puppies well being. If he seems tired or lazy it could be from lack of sufficient food intake.