I've read you're not supposed to use human hair products on yorkies because of the different ph's between the two. The ph may be different but I've yet to see any scientific study showing human hair products will damage a yorkie coat. In some of the older yorkie books I've read, you would be shocked at what they used for coat care!
If your product is working, not damaging the coat or stinging their eyes, then I would say....use it
