how do i get rid off tear stains on white shih tzu

First, get the vet to make sure that there's nothing serious causing the excess tear production (ingrowing eyelashes, narrow tear ducts etc).

Then mix up a solution of a teaspoon of bicarbonate of soda in a quarter pint of warm water and bathe the stains, taking care not to get the liquid in the eye. After a couple of weeks you should see a marked improvement.
:)

thanks i will give it a go

Wipe daily with Optrex
there is boric acid in it and this helps remove the staining
its perfectly safe even if it goes in the eye as its a wash.

thanks carolyn i will give it a go