They can get dandruff and you can use the selson blue shampoo for humans on dogs with certain skin issues like dandruff.

There are ways to help prevent it. Only bathing her when neccassary, making sure she is on a good food, during winter the dry air doesn't help either so she may need some extra oils in her food to help, like safflower oil. Only a tiny amount though as she is small. Too much can cause a loose stool.
I'd start her off with maybe a quarter of a teaspoon if she has no ill effects from it you can very slowly start to add a little more, if she developes loose stolls just reduce the amunt you are giving her.