Hello, Many, if not all, of the puppies will have plump bellys due to the fact that they are housing their biggest organs in this area. Just like human babies, and of course they will just like puppy babies lose that baby fact. I love to hold those precious little chunkies when they are little.
If you don't have a JRT/mix you should consider one-- no better dog in this world!
Stef, Belgium, JRT Lover from Texas!