An off bite is an underbite in her case. Her top teeth are behind her bottom teeth. The front teeth--incisors--needed to be filed (floated) when she was young. Once the top teeth get stuck back there the top jaw can not grow against the resistance. Her molars line up fine-so that's why it's not a problem for her at all--horses don't need their front teeth to line up in order to eat. They do need their back teeth to chew.
Horses need thier teeth floated on a regular basis--checked at least once a year. No one wanted to touch her incisors--dentists usually only float the back molars. But the famous dentist in the west emailed me about what needed to be done over a year ago. No one would do it. I can tell her top jaw wants to line up--I watch it all carefully--but it can't. There's still a chance it could straighten up when her permanent teeth come in. My vet just gave me the number for the equine dentist at Cornell--so I'm going to try her.
Horse folks encourage the breeding of only perfect animals--but in this case--after thinking about it for 2 years and watching her and researching--I'm comfortable with breeding her. But not for 2 years at least. If a perfect buyer happened along--I'd let her go. Maybe. :wink: