From the back of the neck to the base of the tail, the coat should be a dark gray to a black colour, and the hair on the tail should be a darker black. On the head, high chest, and legs, the hair should be a bright, rich tan, darker at the roots than in the middle, that shades into a lighter tan at the tips, but not for all dogs. Also, in adult dogs there should be no black hairs intermingled with any of the tan coloured fur. Adult Yorkshire Terriers that have other coat colours than the above, or that have woolly or extra fine coats, are still Yorkshire Terriers. The only difference is that atypical Yorkshire Terriers should not intentionally be bred. In addition, care may be more difficult for "woolly" or "cottony" textured coats, or coats that are overly fine. One of the reasons given for not breeding "off-coloured" Yorkies is that the colour could be a potential indicator of a genetic defect that may affect the dog's health, a careful health screening can clarify if any health risks exist. Coats may vary in colour. For example, a grown Yorkie may have a silver/blue with light brown while another might have a black and creamy colour.