Maybe it can be the way the breeder raises him?
Before I got my puppy, she kept him away from his litter mates and mommy for 1 1/2 weeks so by the time I picked him up, he was used to being alone. She played with him a few hours a day and put him back in his own pen and he slept without a peep. He hasn't peeped here either. He'll wait until he sees people moving around and if he wants to play he'll let out a little tiny yelp or two but other than that.. no barking at all.
Possibly, you can ask your vet how she's prepping him for his new home. I think small little things help the outcome of the puppy's behavior.
