Bald knees not sure what you mean? Does he not have any fur at all on them? If that is what you are asking then I feel he should have fur, sometimes when dogs get older and if they lay on concrete the fur will rub off on their Elbows.
As far as size how big is his Mama? You said 15 inches from the shoulder? did this mean 15 " from the shoulders to the ground? If so that is not that large for a adult. Maybe I'm misunderstanding what you meant and someone else can answer that.
Cinnamon has a thin wire coat and when she sits, it appears that her "knees" have no hair on them. However, when she stands or lays down with her legs straight out, the "baldness" goes away and it looks normal. Is this what you mean?
yes it could be that. its his back legs-when he sits down his knees look bald- its probably just me fretting about nothing. :lol:
as for his size-leo is 15 inches at the shoulder at 16 weeks. his dad was a lot taller i would say at least 30 inches-his mum wasn't a lot smaller but he soesn't seem to be very big even though he was the biggest from the litter