If the puppy is on the small size too, besides social skills, she could be at risk of getting hypoglycemia. Please read attached brochure (far right side 3rd bullet down) from the Yorkshire Terrier Club of America (YTCA) recommendations:
http://www.ytca.org/Breed%20Brochure...20graphics.pdf and
http://www.ytca.org/faq.html#E
Here is their main site:
http://www.ytca.org/mainview.htm