I have NEVER experienced this before and was wondering if anyone here has had any experience, good or bad, with this situation. I have a girl whom has had a correct bite up until she turned 9 months old. Went to a level bite, and now at just over a year is an SLIGHT underbite (VERY SLIGHT, but still, its an underbite). WHAT HAPPENED??? She is a slow maturing girl,and her head has changed so much in the last month. Any opinions??

Her head is still growing - her bite may still correct.

I have seen bloodlines where the bite goes off at age 4! Talk about maddening........

I had a bitch who made me CRAZY with her bite. It was over,it was under,it was level...... it finally stopped changing at around 18 months and was a perfect scissor.

I would not consider you bitch unusual at all by today's growth patterns. Talk to the breeders of the lines, they will know

Hi..the jaws grow at different rates but should settle at 13 or 14 months. If she were mine I'd give her large knuckle bones..raw and let her dig into them.
Good luck PS she will digest parts of the bone and and it will come out the other end as white stool!