Underbite

Question
I just recently got a female schnauzer that has a underbite.  She is still able to raise puppies, what are the possibilites that she would pass this on to her puppies.

Answer
An undershot bite is a serious genetic defect as it is a skeletal issue. A dog with an underbite has a lower jaw that is longer than its foreface, and she will reproduce this, as well as wry bites, which is one jaw bone being of normal length and the other being too long. (The jaw is comprised of two separate bones.) This often occurs by breeding a dog with a longer head to one with a shorter head, as the upper and lower parts of the jaw/head are inherited separately.

Teeth are meant to align in an intermeshed pattern on the side of the mouth, with an upper tooth fitting exactly between two lower teeth, to give a dog maximum holding and killing capabilities (if they still lived in the wild). When a dog no longer has this proper alignment, one can gets mouths so extreme that the dog will have problems closing its jaw properly, and the tongue may hang outside the mouth.

Your bitch should be spayed as she is not breeding quality.