To add onto what Megan said, typically, horses need their teeth floated every two years, however this can vary greatly. I know some horses who need their teeth done every nine months. It depends greatly on their diet. Signs a horse needs their teeth floated include:
Difficulty keeping weight,
Reluctance to eat/eating very slowly,
Reluctance to accept a bit into their mouth,
Reluctance to work,
It is necessary to make follow your horse by the equine dentist:
- Before the backing and at the beginning of his work
- Every year or two years according to each horse
It is also necessary to pay attention on signs suspect as bad chewing or/and digestion.
Horses in the meadow may also have more problems, in particular brood mares or old horses.