I agree with Dara though I know some do not. We had Sophie flown to us on Pet Air from Mo.Pet Air specializes in shipping show dogs and puppies around the world and when our vet saw her he said "you've got a really good one here". She is now 10 months old and has never been sick. She is very healthy and strong.
I would be careful choosing the airline and the breeder. I spoke directly to the breeder and visited their web site, Yorkies of Walnut Hills. We keep in contact with our breeder and update her often with pictures. You can see all their previous puppies and their parents on their site. Their puppies come with a health guarantee. We had a very positive experience.
Jackie & my 
Sophie 