We bathe our two dogs every other week, we use puppy shampoo even though they are over two years old. The reason for that is my husband was using flea shampoo and it got into Perrys eye and burned it. We had to take him to the Vet and put medication in his eye for quite a while. It did heal and he is fine now.
Too much bathing will dry the skin. We also brush them every day and we feed them canned Natures Receipe Lamb and Rice in the morning and dry lamb and rice in the afternoon and it keeps their coat very nice and shiny.