When and why do you use extended heels for shoeing hind feet?
Farrier and vettec representative Martin zimmer on why and how to use extended heels:
Trailers and extended heels
Extended Heels can be beneficial for horses that need a palmar extension but have problems with bar shoes. Examples are flat feet with underrun heels. If this situation is combined with a prolapsed or sensitive frog, a bar shoe is often of limited help, as it would bring too much pressure on the frog or prevent a correct fit. Another difference is as well that the maximum extension of an eggbar shoe, for example, is located at the centre of the bar, whereas extended heels, as the name indicates, extend maximally behind the lateral and medial heels. This can provide more stability and support than an eggbar shoe. As the extended heels can lead to earlier landing, they are also a good device for horses that grab with their front shoes. In cases were the earlier landing “shortens” the movement of the hind legs too much but the extended heels help the horse statically, they can be combined quite effectively with a square or rockered toe. In this way they still give more surface and stability, but the toe modifications counter the extended heels’ possible negative side effects.