Heel-First Landing: A Good Indicator of A Balanced Trim
Photo 1: Walking downhill to show full extension of all foreleg joints; here we see the hoof "flip" forward just before making a heel-first landing.
Photo 2: Walking uphill to show what toe-first landing looks like. None of the foreleg joints are in full extension. Just after this moment you would see a navicular-stressing "wobble" or "ka-chunk" in the pastern joints as the horse puts its weight onto the leg and foot.
Photo 3. Showing the moment of breakover - the heel begins to lift off the ground at the back end of the stride. (Here the horse is turning and breaking over slightly away from the camera.)
Recently the barefoot movement and its veterinary researchers have come up with a reliable way to tell whether a hoof is well-trimmed overall. Traditionally, people understood the importance of breakover to a horse's best athletic movement and to long-term soundness. Since perhaps the end of the horse's use as the main means of transportation, in the early 1900's, this understanding has gotten lost in the fog of a different style of trimming. The movement of most horses has deteriorated as the "long-heeled" trim has become the style in farrier schools. In recent decades, many horse people have almost never seen a horse moving well. When I first saw my mare's feet start to land correctly, I thought it looked 'artificial'!
The indicator of a good trim is that, when going on level ground, the front feet will land heel-first. Just before the heel lands, you will see the foot "flip" forward as all joints in the leg go into complete extension. In a horse with an incorrectly balanced foot, the toe lands first or the foot may land flat. With toe-first landing, you will see a little 'wiggle' in the pastern bones - you can almost hear them go 'ka-chunk' - as the horse puts weight on the foot.
(Note: The hind leg joints bend differently from the front leg joints, so that the hind leg lands heel-first almost irregardless of how the foot is trimmed. When I talk about how to trim a foot to get it to land heel-first, I am talking about the front feet. We don't trim the hind feet this way because they don't need it, except in the unusual situation where the toe has gone long-out-in-front; here we can use the trim method temporarily until the toe has been brought back closer to the coffin bone.)
We can see the difference between heel-first and toe-first landing by walking the horse downhill and then uphill on a slight slope.
1) Watch your horse walking downhill (Photo 1). There is plenty of time for the front leg to extend fully before it reaches the ground. You will see the foot "flip" forward as the leg reaches full extension, and then the hoof will touch the ground heel-first.
2) Then watch him walking uphill (Photo 2). There is not enough time for the leg to extend fully before the ground arrives. The toe touches first and then you will see a "wiggle" or "ka-chunk!" in the pastern bones as the horse weights the foot.
3) Now, to discover whether your horse is "officially" landing heel-first or toe-first, watch him walking on level ground, and notice how the front feet are landing. Sometimes they land exactly flat, which is better than toe-first, but can be improved further by trimming as I will show below.
What is breakover?
1) the moment in time when the foot starts to tip forward to lift off from the ground (Photo 3)
2) the position of a line across the toe, indicating where the foot is able to tip forward for liftoff (Diagram 1).
What does breakover have to do with heel-first landing?
Diagram 1. Right arrow shows where the breakover line is on a farrier's flat-bottom trim or if the toe is flared forward. When the breakover line is this far forward, breakover is delayed and the leg only has time for a shortened stride and a toe-first landing.
The location of breakover determines whether the foot will have time to land heel-first, or not. If there is a long, flared toe that delays breakover, the foreleg doesn't have time to swing far enough forward to land heel-first - similar to walking uphill - and will land toe-first instead; the entire gait is shortened. Delay in breakover also causes forging because the forefoot doesn't move out of the way in time for the hind foot to land on the same spot.
In the wild hoof, which travels 20 miles (30 km) daily, the white line is healthy and tight; it holds the coffin bone high up inside the hoof capsule. The foot is therefore able to wear quite short, often less than 3 inches (7.5 cm) toe length (from the hairline to the ground, front and center). When a hoof is this short, the naturally worn "mustang roll" puts the breakover close to the toe of the coffin bone and close to the bony column of the leg (Photo 4).
In many domestic hooves, the white line is stretched so that the coffin bone sits lower inside the hoof capsule. A typical domestic toe length is 3.5 to 4 inches (9 to 10 cm) with the toe flared forward. Even a well-done mustang roll on this foot doesn't put the breakover close enough to the coffin bone and the column of the leg (Diagram 1).
Farrier Gene Ovnicek, applying the research of Dr. Robert Bowker and others, has been promoting a slight but important change in the barefoot trim for domestic horses whose toe is too far forward for early breakover and heel-first landing. Because excess toe causes a late breakover, Gene has added to the trim method a slight rocker on the bottom of the toe. For these longer-toed domestic horses, the rocker puts the breakover back under the foot, at the same place it would be on a mustang foot (Diagram 1). This makes it possible for them to break over at the right moment to achieve a heel-first landing, along with freer movement and a longer stride.
Why do we want a correct breakover?
Photo 4. A wild mustang hoof (upper photo); left arrow shows where breakover occurs on this naturally-worn foot. Right arrow shows where breakover would be if this horse had lived in captivity, as shown with the same two arrows (lower photo) on a foot with a traditional trim or a toe flare.
Photo 5. I have marked this photo to show the heel buttress line, the widest-part line, and the breakover line. I have drawn a pretend breakover line 'as if' the horse wears off its toe at a slant (due to conformation or an old shoulder injury). The line goes through the spot at the edge of the toe callus, but it slants to match the horse's own wear pattern, focused at the arrow. (Sorry, my clearest file photo for this diagram was a hind foot.)
Everything about the horse's hoof works better when the foot lands on the ground heel-first. The hoof capsule flexes correctly for best shock absorption, best circulation, and balanced wear. The digital cushion is tough and the frog is wide and healthy; they are able to protect the foot from amazing amounts of hard work.
When the foot lands toe-first, none of these things work well. Shock absorption is reduced, there is less circulation inside the hoof, heels tend to become contracted, and the hoof tends to wear unevenly. In addition, the "wiggle" in the pastern bones puts incorrect stress on the impar ligament, which holds the navicular bone in position. The impar ligament gets inflamed from constant toe-first landing. This inflammation, in Bowker's and Ovnicek's opinions, can lead eventually to "navicular syndrome" and/or coffin joint disease.
What balance does the foot need to land heel-first?
In order to land heel-first, the hoof must have a correct toe-to-heel balance (or workable proportion). The best proportion, in a front foot, is about 1/3 from breakover to widest part of the hoof, and 2/3 from the widest part to the heel buttress (Diagram 2). In hooves that land toe-first, the toe section is typically longer (2/3) than the heel section (1/3) (Diagram 3).
As we change the trim, the foot will start to shift from toe-first landing to heel-first landing when the proportion gets to about 1/2 toe - 1/2 heel.
When trimming, we usually need to make changes both in front of and behind the widest part of the hoof:
1) Shorten the heel to the level of the sole; this moves the heel buttress (the back corner of the heel) toward the back of the foot (because the heel grows forward as it gets longer).
2) Make a toe rocker to move the breakover back towards the widest part of the foot.
How to make a toe rocker:
The first time you do this, draw three lines with an indelible marker pen to help you 'see' the balance of the foot:
1) across the buttresses of both heels
2) across the widest part of the foot, about 3/4 inch (2 cm) or the width of your thumb behind the point of frog in a medium-sized horse; farther on a big foot, closer on a small foot
3) across the back edge of the toe callus, about the width of your thumb ahead of the point of frog; you can often see where the toe callus starts to drop off into the concavity. (This line will be farther from the frog on a large hoof and much closer to the frog on a pony hoof.)
This third or breakover line, just behind the toe callus, is where (in relation to the coffin bone and the bony column of the leg) the naturally worn breakover would be on a free-living, naturally worn hoof.
If the horse naturally has an off-center breakover, for instance the shoes or the toe are worn off at 1 o'clock instead of 12 o'clock, draw the 'breakover' line through the spot at the edge of the toe callus, but slant it to match the horse's wear pattern (Photo 5).
Diagram 2. A hoof balanced for heel-first landing. The distance from the breakover line to the widest part of the hoof is shorter than the distance from the widest part to the heel buttresses.
Diagram 3. A hoof with long heels (which moves the buttresses forward) and a flared toe (which moves the breakover forward). The distance from the breakover line to the widest part of the hoof is longer than the distance from the widest part to the heel buttresses.
Diagram 4. Side view of hoof. The line across the toe shows where the rasp makes a flat cut, across the entire toe, at about 15 - 20 degrees to the bottom of the foot. Arrow points at your marked breakover line. Rasp at the 15-20 degree angle until the rasp gets to the breakover line.
1) First, shorten the wall to the edge of the sole, from the breakover line back to and including the heels.
2) Then, in front of the breakover line, rasp at a 15 to 20 degree angle a flat surface across the whole toe. Go until the rasp gets to the line (Diagram 4).
3) Finally, mustang roll (rounded bevel) around the bottom edge of the wall, including the sharp front edge of the rocker. Shorten the bars to slightly shorter than the new wall level, and you're done. This is a surprisingly quick trim to do.
People are often worried about the fact that a toe rocker cuts into the toe callus. Rockering seems to go against the rule-of-thumb that we don't thin the sole. Gene Ovnicek explains it like this: If the toe is flared enough to need a toe rocker (e.g. the horse is landing toe-first), then the toe has been pulled way forward and the callus is not directly under the coffin bone where it should be doing its job of protecting the bone from injury. When you get the flared toe out of the way, the foot and toe callus re-shape themselves very quickly to match the coffin bone, often within the 3 to 4 weeks until the next trim. I have seen this happen regularly.
Caution: DO NOT put a toe rocker on a foundered horse, especially if the sole is bulging downwards, nor on a horse with enough flare that the sole has totally flattened (lost its concavity). The coffin bone can be very close to the surface in these feet, and a toe rocker could expose the bone. Instead , remove flare and put on a mustang roll (rounded bevel), rounding all the way to the juncture of sole and white line. Do this until the white line tightens up and the sole regains concavity; then it is safe to rocker the toe if needed.
"Physical therapy" or re-education of the legs
Once the foot has been given a correct breakover (short heels and toe rocker) it may take several weeks for the horse's legs to learn to move differently. Gene suggests walking the horse (leading or riding at the walk) for up to half an hour daily for the first couple of weeks, on smooth pavement. The hard, flat surface gives the foot a very clear signal as to when it can break over, and this allows the leg to get used to swinging farther forward to land on the heel. I found that my horse landed heel-first 1 step in 10 the first day, and the ratio shifted gradually until after several weeks he was landing heel-first most of the time.
When a hoof is consistently landing heel-first, its entire physiology and its flexion are able to work correctly. Trim problems that we have not been able to resolve will resolve on their own. A coffin bone that is sitting crooked inside the hoof capsule will level itself over several months without our frustrated efforts to "make it level." Unidentified heel pain from an inflamed impar ligament disappears. Contracted heels will widen; in my two horses, all of the heels became 1/2 to 3/4 inch (1.5 to 2 cm) wider between the buttresses, within a couple of months, and the feet became nearly round where they had been oval for years. The digital cushion gains in toughness so that the horse can go more comfortably on rough ground. And the great delight: riders are reporting to me that "My horse now has big 'dressage-y' movement, it's such fun to ride!"
The heel-first landing is a useful discussion point, if your horse is still shod, to explain to the farrier why you'd like him to shorten the heels and back up flared toes. You can ask him to rocker the bottom of the front shoes. On a shoe, the breakover line should be about where the back corners of side toe clips would be. It looks like a lot of rocker, but the shoe adds more length on the bottom of the hoof, so the line needs to be back that far in relation to the leg. You can also rasp a rocker on your hoof boots so your horse can land heel-first on trail rides.
To sum up
This simple observation - how a horse's front feet land, heel-first or toe-first - is an excellent indicator of whether the trim is balanced or not. It only takes a slight deviation away from the 1/3 - 2/3 toe-to-heel natural balance of the foot to make it land toe-first. When we see a horse landing toe-first on level ground, we can look at the feet to discover what is making them land that way, and address this imbalance.