FIGURE 1. A sound, domestic bare foot that is self maintained.
Achieving hoof balance comes easily once you know where to start, says Gene Ovnicek, a farrier with Equine Digit Support Systems in Penrose, Colo. The key is finding the widest part of the hoof, which then allows for correctly locating P3 and trimming and shoeing for proper support and breakover around P3.
Ovnicek says that many domestic horses often posses misleading hoof capsule distortions that occur because the foot has not been allowed to wear or be managed naturally. He says such hoof distortions are so common that farriers routinely mistake them for normal.
Many farriers expect and rely on the coffin-bone-to-hoof-capsule relationship to never change. “In fact, hoof capsule distortion is very common and increased leverages on the coffin joint are the end result,” he says.
Another problem is the widely held belief that only the hoof wall should bear the weight of the horse, he adds. That belief hinders a farrier’s understanding of foot biomechanics and their ability to identify common hoof distortions, and it can lead to improper trimming and shoeing, according to Ovnicek.
“There is a lot more to the foot than what I was taught when I started to investigate the hoof from a farrier’s perspective. At one time, I believed the hoof wall was what they were supposed to walk on,” Ovnicek says.
“But the science of the horse’s foot is ongoing. A lot of the things that we thought were important, maybe aren’t so important and need to be rethought. To stand still on the laurels we’ve evolved to in the last couple of hundred years might not be in the best interest of the horses,” he says.
“The horses are changing in their husbandry issues, and we need to hone in on some of the newer ideas now that we have the technology to see the foot more clearly,” he adds.
Ovnicek’s technique for balancing the hoof, often referred to as the Natural Balance method, ties together studies of wild horse hooves and the work of researchers David Duckett, Mike Savoldi and Bob Bowker. It is based on the idea that a healthy hoof left to wear naturally will adjust and shape itself to provide optimal biomechanics, Ovnicek says.
For example, he says, “A flare is Mother Nature’s way of bending the hoof wall so it can be more easily broken away. The breakage that occurs in the quarters is a normal thing. These are the kinds of simple things that I’ve looked at over the years.”
Farriers who believe that the hoof wall alone should support the weight of the horse would not see the breaking of the hoof wall as a good thing. However, Ovnicek contends that the hoof wall breaking away is a part of its natural maintenance program.
“The foot’s internal structures are dependent on the solar structures to take over the support and protection duties while the hoof wall refashions itself due to wear,” he says. “By looking at these things with common sense, you’ll gain perspective on how the foot maintains itself on its own when it has the opportunity to do so.” (Figure 1.)
Where To Begin
FIGURE 2. Proper hoof mapping allows a farrier to locate
Ovnicek defines balance as: “A state whereby the hoof wall, sole, bars and frog are prepared so that an equilibrium exists in and around the coffin joint. With a shoe placed on the foot, a maximum base of support should be provided while minimizing the stress and leverage to the lower limb, both statically and dynamically.”
As the first step toward achieving balance, he says, “Find where the widest part of the foot is, because its relation to the coffin bone never changes. The true frog apex also doesn’t change in relation to the coffin bone. Using those two landmarks, you can map out the foot and divide it proportionately equal on both ends and successfully maintain the hooves.”
Ovnicek offers three ways to locate the widest part of the foot, regardless of hoof distortions:
• Measure back 1 inch from the true apex of the frog. (Figure 2-A.) A line perpendicular to the frog at this point is usually the widest part. However, if the frog appears stretched or pulled forward, you must refer to the second and third options.
• Find the two points where the bars terminate into the commissures and a bulge or swell can be felt. (Figure 2-B.) A line across the foot through the two points should be the widest part of the foot.
• Working from the toe quarters back to the heels, remove the chalky material from the sole until the live, waxy surface is revealed. Draw a line along the wall/sole junction from the toe quarters to the heel. (Figure 2-C.) Mark the high point of the arc of the line on each side of the foot, then connect the marks with a line across the sole. This line should be the widest part of the sole, hence the widest part of the foot. (Figure 2-D.)
From the line marking the widest part of the foot, measure forward 1 inch on a #0- or #1-sized foot to find the true frog apex. Measure another 1 inch forward to locate the tip of the coffin bone. (Figure 2-E.)
Mark a line 1/4 inch ahead of the tip of the coffin bone to indicate where the breakover should be located for trimming or shoeing. (Figure 2-F.) When trimmed or shod using these parameters, the hoof is properly balanced, Ovnicek says.
Ovnicek notes that his method of balancing the foot agrees with the research by Duckett, who contended that breakover should occur just slightly forward from the tip of P3.
“Any amount of extra hoof that extends beyond a given point creates extra leverage and strain on the distal interphalangeal (DIP) joint. The foot is worn away on the toe, and all shoes wear away at the toe,” Ovnicek notes, as nature strives to maintain the breakover point close to the tip of P3.
“Stopping the hoof wall from extending too far forward is important for hoof maintenance — that’s why the front of the foot or the shoe wears away,” he says. “If you ride your horses barefooted and maintain them barefooted, they will do the same thing. They will maintain that foot if they have enough activity to do it.
“In light of the check apparatus, which is the same mechanism that allows the horse to stand and sleep, it is normal for the horse to wear away the front of his foot because the leg is held rigid through the loaded phase of the stride,” he says.
“If you don’t see wear at the toe, then the ground resistance is too forgiving, some lameness is apparent, or the toe is so long that the knee will release prior to the heel coming off the ground in order to protect against the added strain on the tendons, ligaments and DIP joint,” he adds.
“Then the rest of the body has to adjust to release that foot, which throws off the timing of the animal. Think about what that means for dressage horses and running horses; how that long toe can interfere with the timing of the whole body’s movement.”
Wear Or Tear
Ovnicek notes, “It’s often said that we can’t use wild horses for comparison because we don’t ride them. Despite not being ridden, they’ve worn their hoof wall to the most optimal biomechanical form in order to reduce the leverages to a point that far exceed what we think of as normal.”
On domestic horses, he says, “If no allowance is made for wear that naturally occurs on the front of the foot, you’ll increase the strain on the navicular bone, the collateral ligaments and the deep flexor tendon.
“It boils down to excessive leverage on the joint and the tissues around that joint, which leads to what has commonly been called navicular syndrome and caudal hoof pain,” he says. “These things have not been as visible in the past as they are now with the sophisticated ultrasound and MRI equipment.
“MRIs today are showing very clearly that there are lesions or damage to the collateral ligaments, deep flexor tendons and impar ligaments. All of these can be seen before the disease accelerates to an irreparable degree,” he says, and natural balance trims and shoeing can relieve the condition before it becomes irreversible.
Ovnicek says research shows that the hoof wall is designed to maintain itself close to the level of the sole and that the sole is designed to bear weight and share the load.
“Don’t misunderstand; I don’t advocate or want to produce sole pressure. If the sole extends above the level of the wall, that’s trouble,” he says. A trim should put the sole at exactly the same level or slightly below the height of the wall, he says.
Ovnicek notes that research by Duckett and Bowker indicate the presence of pillars and calluses through which the sole helps support the weight of the horse. Those structures are also evident in his own study of healthy feral horse hooves, he says.
He spray-painted a board, then pressed the board against the bottom of the hooves to create an imprint of the highest points. “Some of the horses had no hoof wall touching the ground
at all,” he says. “Those horses had been on the most abrasive terrain.”
On many of the horses, he says, the high points seen in the imprints included the spots that Duckett referred to as “pillars,” stronger areas of the sole located in the medial and lateral toe quarters.
Ovnicek also notes that Bowker’s work at Michigan State University found that on barefooted horses, particularly wild horses, there is a higher density of lamina in the medial and lateral toe quarters. The lamina between the quarters was not nearly as dense, and some had no secondary lamina.
The areas with the densest lamina seem to correspond to the location of the pillars on the sole just inside the wall identified by Duckett in the early 1990s, he says. (Figure 2-G)
In addition, Ovnicek says, a tougher portion of the bottom of the foot known as the sole callus protects the dorsal-distal border of P3, as well as the circumflex artery and vein, which are closer to the ground than the bone. The sole callus also supports the dorsal aspect of the coffin bone, and it regulates hoof wall wear, he says.
The posterior edge of the sole callus on the ground surface extends about 1/4 inch ahead of the tip of P3, Ovnicek says, and the front edge of the pillars seems to be where the breakover point is most efficient. (Figure 2-F.)
FIGURE 3. The sole callus is generated by the terminal papillae that radiate from around the distal border of P3. The sole callus helps to support and protect the distal border of the P3, as well as the circumflex artery and vein.
“If the sole callus did not protect the bone, this species of equine would have disappeared thousands of years ago. So the sole around the tip of the bone has to have a special protective quality,” he says.
The sole callus is generated by the terminal papillae, which radiates from around the distal border of the coffin bone, according to Ovnicek, who references Pollitt’s work. Again, the sole callus helps protect and support the fragile border of P3, as well as the circumflex artery and vein. (Figure 3.)
See For Yourself
Ovnicek tells farriers, “If you don’t see pillars, imprint the foot. Spray paint a board and press the bottom of the hoof onto it. If the foot is well worn and doesn’t need any maintenance, you’ll see definitions in the bottom of the foot that you’ve never seen before.”
He adds, “As I’ve hot-seated a lot of feet, I’ve begun to see what Duckett was talking about and how he thought there was something special about this region of the foot. Because if you leave enough of the sole, a little raised area around the wall, and hot-seat the foot, you’ll see these raised areas every time.
Ovnicek stresses that farriers should not remove too much of the sole and that one of the most common problems he sees is feet that are trimmed too closely.
“Simply trimming the foot too closely can be the most devastating thing there is to the horse. It can cause pedal osteitis and hoof distortions. I’ve seen three horses that have lost their lives to laminitis because of continual close trims. It’s easy to set the horse up for potential disaster with trims like that,” he says. “Before you know it, you’ll lose the integrity of the bone within the hoof capsule.”
He adds, “There seems to be a unique relationship between the tip of the bone and the wall. When the foot is trimmed too close to the bone, the wall seems to migrate forward very quickly, especially if there is weight on the wall, and the coffin bone settles.
“The horses that have a very flat sole, a long, skinny frog apex and a dorsal wall that runs forward and can’t be controlled are all victims of being trimmed too close,” he says.
Accepted, Not Correct
FIGURE 4. A representation of shoeing protocol for trimming more of the heel to establish better length, width and support, and by moving the breakover under the foot with plenty of sole depth and protection, to decrease the leverage and strain on the DIP joint.
Ovnicek believes too-close trims are often tolerated despite evidence that they hurt the horse. “I have never been able to understand how horse owners can justify a horse being ‘off’ for a few days after he’s shod and accept that as normal,” he says. “That could be something that creates the hoof distortions that lead to lameness.”
But Ovnicek acknowledges that from the farrier’s perspective, close trimming might seem justifiable. Citing his own experience, he recalls that he was trained to trim the toe and leave the heel when he saw a broken-back pastern axis.
“It looks like it might make mechanical sense,” he says, “but not every horse can have that done comfortably. Not every horse has enough sole thickness to do the job. But it was my job as a farrier to get the pastern lined up, so I was going to take as much as I could. I even got good at getting them close. I think that’s the criteria a lot of farriers are still using.”
Now, he says, he understands that trimming more of the heel to establish better length, width and support, and moving the breakover under the foot with plenty of sole depth and protection, will decrease the leverage better than taking anything off the bottom of the toe. (Figure 4)
“Simply trying to maintain pastern alignment by taking the toe and leaving the heel can create the very problem that you’re trying to overcome,” he says. “In my own experiences over 45 years, I’ve had many challenging feet that I couldn’t get enough off the toe to make the pastern line up. In trying to do so, I would create a sore horse every time and I would perpetuate the ongoing dorsal wall distortion.”
Up And Down
FIGURE 5. A bottom view of the finished foot from Figure 4.
Trimming for the proper heel position and breakover point will help ensure the correct alignment of the pastern, according to Ovnicek.
“How the foot gets off the ground influences how the foot comes into the ground. That is important because we’re always concerned about alignment of the pastern,” he says. “The alignment is most important when the foot engages the ground. As the heel comes to the ground, the forces are still going forward and will be accepted into the coffin joint in proper biomechanical form.”
He says the frog is partly responsible for aligning the pastern. “The concept isn’t talked about much until you do the science,” he says. “Horses that land heel first will have the coffin bone, P2 and P1 lined up every single time, particularly when the frog is in contact with the ground.”
He adds, “Taking the frog out of the picture defeats what we’re trying to do. Raising the heel to align the pastern has some mechanical advantage, but the purity in the whole procedure is engaging the frog as well as the angulation of the foot.”
Proper trimming improves the quality of the back part of the foot, he says. “Exfoliating the foot, trimming to the level of live, waxy portion of the sole or very close to it, will uncurl the heel. It will move the buttress back and make it wider.
“That’s not a brand new thought. However, I spent years raising the angles and creating a lessened distance in the back of the foot, crowding the widest part,” he says.
A Healthy Fit
When applying shoes, farriers should consider that the closer they can get the breakover point to the tip of the coffin bone, the less stress there will be on the coffin joint, Ovnicek says. (Figure 5-A.)
He cautions that horses that are base-wide, base-narrow and that land lateral toe-first are most prone to developing coffin joint disease. In light of Mike Savoldi’s work regarding uniform sole thickness, Ovnicek says, the use of the live or functional sole for both medial-lateral and anterior-posterior balance is of paramount importance when trimming these types of feet.
Also, he says, “You increase the leverages on the foot with a shoe that is wider than the foot. I used to think that I needed a wide-based shoe. I’ve changed my thoughts about that. If you use a shoe that’s much wider than the foot, there will be lateral strain on the joint when breakover occurs.”
“When you reduce the leverage on the front, you stop hoof distortion from happening,” he says. “You can reshape any shoe in your truck to fit. Modify it any way you need to, and extend the heels to the back of the frog buttress.” (Figure 5-B.)¨