Toe Rocker

The application of a toe rocker or bevel to a hoof improves breakover and encourages a tighter connection between the hoof wall and coffin bone.

In a healthy hoof the hoof wall is tightly attached to the coffin bone. The coffin bone and hoof wall both have structures call laminae attached to them and these laminae interlock with each other to form a very tight bond - imagine the bond as a closed zipper or a velcro fastening.

As the hoof wall and sole grows down and away from the bottom edge of the coffin bone the old laminae form the white line which is visible when looking at the sole. When there is a tight connection the white line will be approx 2-3mm wide. If the connection between the hoof wall and the coffin bone is compromised this will be reflected in the white line which will be wider - the bottom of the zipper is now starting to open. The wider it is, the worse the connection.

Sometimes the sole stretches forward and hides the stretched white line making it appear to be healthier than it really is. There are two ways to double check if this is the case on your horse. The first is to look at the angle of growth of the wall at the toe. Is the angle tighter (steeper) at the top than the bottom? If it is then the white line is stretched. (See second set of illustrations below - the dotted green line shows the change in angle.) The second is to look at the sole. Is there a ridge around the toe and then a gap between the ridge and the hoof wall? If so you probably don't have a really tight connection.

Breakover

The hoof is designed to breakover in a position that applies the least amount of stress on the laminar connection. This point is at the outer edge of the toe callus on a healthy hoof.

Therefore the point of breakover on a healthy hoof should start at the white line. Any further forward and the laminae will be stressed.

The illustrations below show the difference between a traditional farrier trim, (first illustration) where the hoof wall is trimmed flat, compared to a barefoot trim (second illustration) where the bevel and mustang roll have been applied. Notice how much farther back the barefoot trim brings the point of breakover - reducing the stress on the laminar connection.

Using a bevel or toe rocker is even more important when dealing with a horse that has laminitis and rotation and a stretched white line.

In the following illustrations the first one shows how far forward the toe can get with a regular "flat" trim. The second illustration shows how it is really important to start the rocker at the back (the side closest to the sole) of the stretched white line as indicated. If you apply it starting at the front edge of the white line the breakover will still be too far forward and the wall will continue to be pulled away from the bone.

When applying the breakover however, you must be very careful not to rasp into the toe callus else you will lower the height of the toe (measured vertically from the hairline at the toe to the ground). The start of the breakover should be just in front of the highest point of the toe when looking at the sole and should angle out at approx 30 degrees.

Trimming a Toe Rocker

Here is a series of photos showing a toe rocker being trimmed on a pony with a stretched white line - please note, this pony has damage to his coffin bone, which why his toe angle is so low. However by applying the toe rocker we can improve the white line connection over time.

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