You don't really say, but is her hair growing at all? If it is, then you'll just have to be patient, just like with our hair, it takes time. Rhett's Mama is right, if you're feeding a good quality food, she should be getting needed nutrients from it and shouldn't need supplements or vitamins.
Now, there are some yorkie coats that will never grow out, they are just the wrong type to achieve a long flowing coat. My Ruby is a silk coated yorkie but hers is a very fragile silk and breaks off easily, so she'll never have a coat that touches the floor.
__________________  ~Ruby, Reno, Razz, & Jack~ |