A lot of the yorkie owners on this forum use human shampoo on their furkids. I used to.. i know that it is different pH and all that stuff, but my dogs have never had a reaction to it, and i always made sure to rinse out very, very, very well.
I no longer use human shampoo on them, but i do use the chris christensen systems on them and their hair is awesome, you might want to check it out.
www.chrissystems.com