I have a heifer like that. We didn't find it until she was six months old. I can spend more time watching the animals that my dad could, so I just kept her, watching to see how she was affected by this malady. Her input and output was good, she drank water fine, she chewed her cud, and I could take the time to pull apart her feed. Finally, I had the vet in to see just exactly what he could tell me about her jaw. The teeth just almost straight down, and unless you get down and look specifically at that lower jaw, you can't notice a thing wrong with her. We thought maybe her mom had kicked her, or she had gotten stepped on. The vet said that she had been born with her lower jaw upside down. He said her mom must have been a fantastically patient cow, because this calf probably took a long time to nurse. of course, she will never leave our place alive, and she is just over two years old now. The vet said that since she was born this way, the likelihood of her ever fighting gum infections were almost nil, and he has been correct so far. She grazes fine. She would have been calving this year, since the vet was pretty sure it was just an accident of birth NOT an inherited trait, but to our dismay, we found that she had been bred at six months. Her calf died, but if we had taken it a bit sooner, it would have been a perfectly formed, healthy calf. Hope this helps a bit.