As others have noted, Yorkies often weigh more than 5 pounds. Our Bella weighs 7 pounds. The DNA testing is about 96% accurate, which means only 4% chance of crazy results. If those odds sound good to you, and you have the $79.99 for it, I'd recommend the Wisdom Panel test, just to give yourself some peace of mind:
Wisdom Panel® 2.0 | Wisdom Panel