Is the mare producing live foals that die or having spontaneous abortions?

The horse shorer said that she has the hoof deformity from birth or could it be a case of chronic laminitis? If the latter is the case, she should not be shod. If the pressure on her heel is due to a rocking back on the feet, extending them forward at rest, she probably was foundered in the past. (Pain could cause the abortions, among other things.) By allowing her to go barefoot the pressure would be more distributed to the frog. Frog pressure makes the feet grow and new growth is necessary, particularly if, by homeopathics, the new growth is healthy hoof. Foundered horses have a tendency to grow toe faster than heel. If not shod she can better ware off the toe naturally. Surprisingly, chronic founder hoof deformity is best treated by keeping the HEELS trimmed (not the toe) in order to get frog pressure. Perhaps the soil where you are is very sandy and they are hesitant to not shoe the horses. They might try one of the hoof dressings to keep her walls in good shape, pliable, and try letting her go barefoot for a while. (Even if not laminitis damage, the approach might be the same.)

There are other reasons for hoof deformity, such as too much selenium in the soils, hay or pasture but the long toe is a key for past laminitis.

Good luck to her......