Jackson had an overshot jaw, so the opposite problem of yours. I noticed it a week after I brought him home at 9 weeks old. All that hair covered it, I guess! It wasn't terrible but it was overshot enough to cause him surgery at 3yrs old.
What happened was one of his bottom canine tooth was poking him in his upper gums/palate since his jaw was aligned incorrectly. So it was causing a hole/indent to be made in the upper palate and eventually it would have gone through to the bone or affected his nasal cavity.
He went to a board certified veterinary dentist (our regular vet recommended us to them, as she could not do anything with it) and they ended up doing a vital pulpotomy on his canine tooth, almost like a filling for humans, they shaved down the tooth so it was no longer poking him and filled it. $1300 later.... he's out of pain! lol.
I don't think I've ever of has many issues with the undershot jaw -- some breeds it's pretty common, or even called for according to AKC (I think) so I guess I'm not much help! |