How Old Do Shitzu Puppies Have To Be So They Can Eat Dog Food?

Pretty much ALL pups can start eating wet dog food at about three wks of age.  I would warm it up a little bit and offer it to them. Also, you can wet dry dog food with warm water and let it get soggy and offer them a little bit of that. Make sure it is puppy food so that they get the proper nutrients that they need (you should also feed a lactating/nursing female dog puppy food and calcium supplements, so she won't suffer calciom insufficiency). Hope this helps!

Do not give your puppy wet dog mood, Check with your vet and let them start you on a diet for them.
I shitzu which is 22 monts old is going through allergic reactions from wet food. Also make sure to keep his ears very clean and wipe his eyes.
Good Luck