[OwnedByJezebel]

Vaccinated at 4 weeks old and 3 lbs already at that point? One source has her at 11 weeks and another weighing in at 3 lbs at 19 weeks old. I can see why you are suspicious. That's all over the place!

They shouldn't be vaccinated at 4 weeks, since they are still getting immunity from momma's milk. I would tend to wonder if that's a faked certificate (given all of the conflicting information) and she hasn't been vaccinated at all, and the vet probably won't accept that certificate anyway.

The vet will probably have a good idea of her age from looking at her teeth. I would not expect your vet to know specific things that a Yorkie owner knows (like the helpful tip that Chachi posted above re coat change vs age). There are just too many breeds out there for a vet to be familiar with the intricacies of every breed, especially those like Yorkies that have changes in coat as they grow.