Recognizing Coffin Bone Rotation
Recognizing Coffin Bone Rotation
Horseback Magazine—Pete Ramey #2 4-10-2013
Q:Hello Pete, I wonder if you can help with a problem we have? My horse had laminitis in the past and we have him on a low-sugar diet, but we are still having issues with the hooves. He seems to have such a long toe, but we just can’t trim it any shorter (we trim the sole as much as we dare and back up the toe to the white line). His heels seem too high, but if we trimmed them the toe would seem even longer. I have sent a picture (figure 1) of one of his front hooves, any help would be appreciated.
A: This is a very common (but serious) problem. You should get lateral radiographs to confirm this, but I think you should instead be trimming the heel and leaving the sole alone at the toe. Look at your horse’s hoof from the side with your chin at ground-level. Do you see that the upper wall growth close to the coronet (hairline) is steeper than the wall growth at ground level? The wall growth at the hairline is probably better-connected and more parallel to the coffin bone—with the lower wall growth separated or rotated away from the bone (see figure 2). Most of the time, when people feel the need to “stand a horse up” they have encountered a problem like this.
When hoof capsules are flared or rotated away from the bone, the tip (front or apex) of the frog will appear to be too far away from the toe because the frog grows from the under-side of the bone. The white line may appear normal, even with significant rotation present. This is because the material produced between the coffin bone and the hoof wall (lamellar wedge) can look much like the sole. Drawing by Karen Sullivan from the book Care and Rehabilitation of the Equine Foot, P. Ramey, Hoof Rehab Publishing, 2011.
The dashed line in figure 3 represents a normal hoof as it should surround the coffin bone. By studying this drawing, you should be able to see why I suggested that you might be going about this backwards (by trimming sole at the toe and leaving the heels alone). In the drawing, the heels are higher than they should be, while the sole at the toe is dangerously thin. Since there is too much material in the back of the foot, and not enough in the front, this also means there is one area in-between that is just right. Be careful not to trim the area that is already correct. This means that as you lower the heels, there will be a rockered appearance to the back of the foot.
Caution: If the sole is as thin as these drawings suggest, special care must be taken not to bruise the sensitive tissues. Don’t let the horse walk barefoot on hard terrain. For horses in this condition, I tend to use hoof boots with foam-rubber insoles, but many devices will work—from elaborate shoeing packages to simple taped-on padding.
A typical rotated hoof capsule. The dashed line represents the location of a normal hoof capsule surrounding the bone. If this idealized foot were cultivated, the frog would be much closer to the toe, the sole at the toe would be thicker, the heels would be low, yet the toe angle would be steeper and more compact. Caution: This does not mean that the foot should be trimmed to mimic the dashed line. Instead, this should be thought of as an eventual goal—acquired gradually with new growth. Drawing by Karen Sullivan from the book Care and Rehabilitation of the Equine Foot, P. Ramey, Hoof Rehab Publishing, 2011.
Lowering the heels must be done with care and consideration. Flexor muscles (and their tendons) may be in excess tension and ligaments may have adapted to the upright conformation. Take measurements and try to gain 1/4 inch per month while monitoring the horse’s stride and comfort. Slow down the heel-lowering if the horse is standing very upright and impacting toe-first at the walk. Speed up heel-lowering if the horse is rocking back on its heels (founder stance). This is a delicate matter that cannot be learned from a magazine article—be sure you have very competent professionals (vet and farrier) on the job.
This drawing represents what the same foot could look like in several months as the rotation is growing out. New growth at the toe has made it halfway to the ground—the lamellar wedge is almost gone. The sole has thickened at the toe, and the heels are at a more normal height. Drawing by Karen Sullivan from the book Care and Rehabilitation of the Equine Foot, P. Ramey, Hoof Rehab Publishing, 2011.
Looking at the picture of your horse’s hoof, I see another very likely factor. When the overall hoof capsule seems too long, yet the sole is also thin, you can bet that the coffin bone has sunk to a lower-than-normal position within the hoof capsule (or more accurately, the coronet has migrated too far upward). If this is the case, above all else, be sure that you leave enough sole to protect the internal structures from impact. This condition can often be reversed, but not if someone is removing excess sole trying to make the hoof capsule appear to be a normal length.
You mentioned that you have already cut sugars from the horse’s diet, but I must stress that this is a key factor. This probably began as a nutritional problem, so can probably not be fixed with hoof care alone. If the diet and hoof care have been adequately improved, in 3 or 4 months the hoof will look strange (see figure 4). The new wall growth below the hairline will appear steeper and more compact than the old growth near ground level, as if the new growth doesn’t match the rest of the foot. This can be alarming unless you understand what is truly happening. It will look much better when the new growth reaches ground-level.
Eventually—if the diet and hoof care are correct—the steeper new wall growth will reach the ground, allowing the sole at the toe to reach full thickness. At that point, even though the heels are much lower than they were, the toe wall will be steeper. Overall, the foot will be more compact, more comfortable and more useful for the horse. Drawing by Karen Sullivan from the book Care and Rehabilitation of the Equine Foot, P. Ramey, Hoof Rehab Publishing, 2011.