She's biting because she's terrified. It's beyond unreasonable that a rescue dog of this age was adopted out directly without foster care intervention. I've had three rescue Yorkies and ALL of them had foster homes before coming to live with me where they learn to adapt to life as a pet in a home and not a moneymaker in a cage.
My latest rescue only tried to bite me when I attempted to brush her. When she did, I shouted a firm NO! and she hasn't tried to bite me since. She also had a lot of strange skittish behaviors like hiding on the lower shelf of a table, etc. until she got the idea that this new home was going to be safe like her foster home and not the nightmare her former home was.
I posted a video about her in the Yorkie video threads. In it you can see some of the quirky things she used to do including backing up from me if I approached her. If I picked her up, she'd scream as if in pain but it was just fear.
Charley Bears worked wonders for that - she learned to sit to get a treat. When she'd start to run away from me after that, I'd tell her to sit and give her a treat. Later, I picked her up after sitting and give her a second treat. Now she sits automatically when I go to pick her up - and given how fat she's gotten since coming home, she now only gets a treat every once in awhile when I pick her up. She even asks to be picked up for "lovins" now.
Hope this helps. If not, you really need the help of a patient trainer who understands rescues. Good luck to you! |