
Sounds like they have not been very well reared. It may also have to do with parents size. What size were they ? are they up to the accepted height for the breed.
They don't sound like a good prospect for future breeding. Those first few weeks are so important, why were they removed from Mum so early ? They needed her to teach them about being dogs.
I had a litter 2 years ago during a very cold spell (think -7 day after day) they had a nice indoor area and access to a large outside pen. They spent most of the time outside. They grew huge coats and were fit well up to size robust pups. They were well fed and properly reared and it had no effect at all on how they grew. The one I kept has always had a wonderful coat, she is well boned up to size and very robust at 2 years old.
I would seriously doubt the source you have got these pups from.
In a numerically small breed it is even more imperative that the breeding stock imported is of excellent quality.
The future of the breed will suffer if the best is not used.
Aileen