Yorkie personality

Question
Hi there.. I have a question for you.  This might be tough for me to actually explain the problem.  We bred our female Yorkie and she had her first litter.  She is a wonderful pet and became a great mother!  All the puppies were healthy, sweet, and we sold all but one puppy that we decided to keep.  The one we are keeping has perfect markings however, her personality is very distant.  Unlike her sisters and brothers she has never really been as loving nor responsive to people.  She is 12 weeks old and has been socialized with other dogs, our family of 6 and has been held and shown as much love as the other pups.  But I can't seem to get any reaction out of her at all. I have used training treats and love and have been very patient with her.   It is honestly the strangest thing I have ever seen and also sad.  When I call her name she will just stair at me and when we hold her she doesn't wag her tail or look at us in any way.  Like I said before I have had so many pets and tons of dogs.  All that I have trained and are smart, loyal, loving pets.  I just feel this puppy is so different and I wonder if anyone has ever had a puppy react like this... Please help.. thanks!!  Stefanie

Answer
Hi,

First things first.  Take her to vet and check her eyesight and then her hearing.  Your description is one I've heard before from people who have pups with poor eyesight and/or poor hearing.   
If you find these two items are ok, then you have to think about (maybe) a neurological problem.  And/Or  a vitamin mineral problem.
While you are getting these things checked, get the puppy on a good Vitamin  MINERAL  tablet.   It will take a couple of months to work if that is the problem.
good luck
nancy