My first little female Chloe (she is gone over rainbow bridge to be with her other furry friends) had real dry brittle hair. After years of trying many moisturizing products, I finally had her hair cut in a cute puppy cut. It grew in and was actually oily and no longer dry and brittle! Chloe being the Tom boy that she was, we ended up keeping it short! But I feel just like humans, Yorkies sometimes need a good hair cut.
. Good luck!