Hi, I love Dozers underbite, so cute. Everyone is right, they can change so much as they are growing, and up to a year old. My Dozer also has a very prominent underbite. He didn't develop this until he was 5 months old and he had a growth spurt. When I brought him home at the age of 10 weeks old, he didn't have any underbite. The vet told me he has a pretty severe underbite, and it's considered a genetic defect. When she checked him further, we realized that his top and bottom teeth don't meet properly, which causes him to eat slower than his sister, and he is congenitally missing a couple of lower molars. He also cannot close his mouth proberly, so his tongue hangs out all the time. I could have taken him back to the breeder and got another puppy or my money back, but I would never consider this, I had bonded with him, and I love his underbite, I think he looks so cute with it, and God made him like that. I think it gives him character. I did phone the breeder though just to let him know that Dozer had this genetic defect, to make him aware of it, and hopefully he would stop breeding the particular dog with this defect.
Here are some pictures of my Dozers underbite: