Yorkies are not supposed to shed much but all dogs will shed a little, just as we do. They might shed more if they have been bred with another dog back in their history somewhere, they are sick, or if they are upset (as mentioned above, some will shed a little when they are nervous). I guess we should just call it losing hairs as they do not shed like a shedding dog. No warm weather purge of undercoat because they have no undercoat. But if you just see a few hairs here & there, that is normal. You may find as many of your own as you do your Yorkie's.