Steppin' Out: Hooves From An Artistic Perspective Part X: The Good Foot Part 4

Hello! We're back again concerning ourselves with hooves and sculpture. We've covered a lot of ground so far, but have a ways to go, this time with the hoof wall. This is the most overt aspect of the foot we'll sculpt, so it's smart to pay keen attention to it. As one can imagine, there's a lot more to it than simply sculpting a pointy blob! So let's have at it!

Wall

Being the most obvious aspect of the equine foot, the hoof wall is an important feature in sculpture. Yet while it may seem like a simple enough structure to sculpt, it’s actually full of nuance and complex mechanics that require careful thought when sculpting. 

Perhaps most provocative, a new picture of the proper hoof has emerged, one which runs counter to traditional thought and sculpting convention. This presents a philosophical challenge for the artist. 

For starters, the consistency of the hoof wall itself has undergone serious reinterpretation based on recent studies that found that it’s not a rigid structure, but malleable and fluid, with an inner wall the consistency of peanut butter (Bowker, 2003). As we learned earlier, this is because the inner wall (often called the epidermal layer, or stratum internum) has a high moisture content and is comprised mostly of intertubular horn (a moist clay-like avascular substance that originates on the secondary dermal laminae) which grows towards the wall tubules at a right angle in a healthy foot (LaPierre, 2004). It depends on the coffin bone’s laminar corium for nutrients to create this intertubular horn and it’s this type of horn that binds the hoof tubules together to create the outer wall. Therefore, it’s now thought that the rigid outer wall, which moves down from the coronet, uses this inner wall layer as a kind of conveyor belt to allow it to grow yet still maintain a tight attachment to the coffin bone through the laminae (LaPierre, 2004). Consequently, the hoof wall is being interpreted now using fluid dynamics as a model, rather than being regarded as a kerantinized static “block.”

In fluid dynamics, it’s known that fluid flowing over a surface is stationary at that surface, with the velocity of the fluid above increasing with depth. Therefore, compared to the outer wall, the intertubular horn can be regarded as a high viscosity fluid (LaPierre, 2004), which has interesting implications for many hoof pathologies in domestic feet (many of which appear to be a by-product of out-dated ideas of the hoof). For example, it’s commonly believed that it takes about 8–12 months for a new hoof capsule to grow from the coronet to the ground. However, while this can be said of the outer wall, it appears this may not be true of the inner wall (LaPierre, 2004). Stimulus to the hoof (shock, wear, pressure) triggers the wall to grow, and increased coordinated growth of the inner wall aids this accelerated growth of the outer wall. When the stimulus is correct, these two layers grow in balance with each other, and with the fluid dynamics model, the coffin bone remains stationary (LaPierre, 2004). However, when these two layers do not grow in balance due to improper stresses or injury, a “buckling” of the outer wall can happen, such as the formation of ridges, rather like how cooled, slower-moving magma buckles above the faster-flowing hotter magma below. It also appears that the tubules change direction to adapt to loading and stress on the wall (Bowker, 2003).

Research also has found that breakover should occur significantly closer to the frog apex than traditional practice allows. For instance, domestic horses typically have toes that are far too long (and often a hoof capsule that’s far too long due to sinking) which “pulls” the entire hoof capsule forward, placing weight-bearing and breakover farther forward and away from the coffin bone. The result is a delayed breakover (and all the problems that brings) and many of the pathological structures common in the domestic population, such as contracted heels, underrun heels, heel pain, toe-first landings, ligament/tendon problems, navicular, bruising, corium damage, and general unsoundness.

In contrast, the feral foot has a very short hoof capsule and a comparatively very short toe, which is typically “rolled” back to the waterline, placing breakover just in front of the tip of the coffin bone. Thus, breakover occurs over the sole (or toe) callus and not at the toe’s wall, as it does in domestic horses. Consequently, breakover in the feral foot is easy, fast, fluid and with long limb extension with no interference, and with no mechanical pulling on the hoof or internal foot due to the “long lever” typical of the domestic hoof. There also is evidence that the laminae in a short-toed foot has a different density and morphology than in a long-toed foot (Lancaster), the latter showing signs of unnatural stresses and stretching. So where breakover occurs has direct relevance to artwork because a foot with the correct placement of breakover looks very different from the typical domestic foot. 

Another important rethinking of the wall is the recognition that “one size does not fit all,” even in the feral foot since the foot is so adaptable to lifestyle. In turn, this effect should be encouraged when it takes a beneficial form, even if that means the foot becomes contrary to convention. Included in this new understanding is a reinterpretation of wall flares and chipping—they aren’t characteristic just of domestic feet, but also of feral feet living in certain habitats, as previously discussed. Therefore, flares, cracks and chips may be part of the hoof’s natural exfoliation process and don’t affect the foot’s ability to support the horse in natural conditions. In fact, they merely indicate that the hoof could be trying to maintain its proper length. In the feral foot, the white line attachment is tight to allow these exfoliating portions to break off, often creating natural caulks for traction. However, the often-pathological foot of the domestic horse usually means compromised white lines, which can present problems during this natural process (and why these portions of the wall are often removed during a farrier visit). Boiled down, chips and flares don’t necessarily mean a hoof is “bad” (Love, 1998).

Perhaps the most radical rethinking of the wall is that, contrary to conventional theory, nature may not have intended it to bear weight, but instead to act more as a protective containment structure, with relatively minor energy dissipation capabilities. Microscopic comparison of the laminae between feral and domestic horses reveals significant and tell-tale differences in the wall. For example, the laminae of feral horses is thicker and fewer in number, with an orientation perpendicular to the ground and at right angles to the coffin bone. In contrast, domestic horses have laminae that are thinner, more numerous and with an angled orientation to the ground and the coffin bone (Henneman). Moreover, shod horses have even more and even thinner laminae than barefoot horses (Chao, 2007), the latter which has laminae resembling that of feral horses. Plus, shod horses with toe clips have even more laminae around the clips (Welz, 2007). This seems to indicate unnatural stress on the laminae.

So in a very real sense, the histology of feral feet reveal laminae that resemble those in a foal’s foot, in terms of number, spacing and structure; i.e. they are minimally stressed (Lancaster). Likewise, Bowker found that an increase in laminae density is a sign of stress, and that the foot will create new laminae, or forked laminae, in those areas of the wall subjected to more stress, even varying in different regions of the wall, depending on the specifics of the situation (Lancaster). Boiled down, the thinner, more numerous and more forked the laminae, the more stressed the foot. Alarmingly, it appears that thin, numerous laminae are more prone to become laminitic, too (Welz, 2007). 

This brings us to a very important new concept regarding the wall: Peripheral loading. As we learned earlier, if it’s the laminae that creates approximately 1/3 of the wall and the inner wall is fluid, and the hoof is highly adaptable, and paired with the new findings about the sole, the “fact” that the laminae suspend and support the coffin bone (and thus support most of the animal’s weight inside the hoof capsule) becomes highly suspect. Indeed, Bowker found no direct connection between the laminae and the coffin bone to indicate support—there’s only dermal tissue intervening between them (Welz, 2007). The study of feral feet and recent research by Bowker suggest that nature never intended the horse to “hang” from the laminae like a sling within the hoof capsule, which exactly is what happens when the hoof wall is made to bear the weight of the horse, a condition now called “peripheral loading” through a trim that loads the wall or the presence of shoes. In essence, peripheral loading transfers support from a broad, calloused surface of the palmar foot directly to the thin, “crackable” ring of the wall, a situation unnatural for the equine foot. Peripheral loading operates in direct opposition to the foot's biology, which may be why this condition leads to so many destructive problems in the foot, and why these conditions are unique to domestic horses, particularly shod horses. 

How does peripheral loading affect the foot? First, it stresses the laminae in ways that appear to affect the stability and quality of the foot. Peripheral loading also interferes with the blood flow inside the foot by reducing blood perfusion within the tissues. Dr. Bowker found that in hooves that are peripherally loaded, blood flow within the foot actually stops momentarily with each heartbeat at the fetlock (Welz, 2007). Furthermore, Bowker found that peripheral loading can lead to bone loss in the coffin bone, too (Welz, 2007). Instead, Bowker suggests that loading is intended to be born by the sole, in unison with the bars and frog, and the primary function of the laminae is to act as a keratinocyte storage (storage of keratin producing cells) and to produce tubules for the sole and white line (Welz, 2007). 

Now because peripheral loading is caused when the wall is made to bear an undue share of loading, the presence of shoes can be considered a peripheral loading device because their application depends on the idea that the wall was intended to be the primary weight-bearing structure. So perhaps not coincidentally, the presence of shoes appears to be involved in many cases of damage caused by peripheral loading. However, this situation also can occur in a barefoot when the wall has become too long or if over-trimming of the sole, frog and bars has “scooped out" their supportive roles. 

Indeed, the need to mediate peripheral loading may be why a foot adapts so quickly to its habitat, such as with horses working on hard surfaces, like asphalt, who will develop soles that “fill in” the distal surface between the palmar foot and the ground surface. Interestingly, in his article, One Foot For All Seasons? (2006), Pete Ramey claims, “It is my opinion that the hard surfaces that are commonly blamed for 'road founder' (mechanical damage to the laminae) are not the culprit at all; instead it is the peripheral loading that usually results from a hard, flat surface. The horse simply needs sole pressure/support.” 

Also, as we learned previously, the inner wall, or “water line,” is of superior construction to bear weight and mediate loads compared to the outer wall, which may be why feral feet and domestic barefeet have walls that wear back to it so that the horse actually walks on the waterline rather than the outer wall. Correspondingly, it’s been observed that growth rings and ridges disappear in hooves that have had their outer walls relieved of weight-bearing by being “rolled” back (LaPierre, 2004), which again suggests that the outer wall was never meant to support the horse. 

Finally, in a feral foot or domestic barefoot, it’s the thick, dense, calloused sole (in particular the sole callus that mirrors the distal border of the coffin bone) that prevents the wall from wearing too short, not the other way around, as conventionally believed. This is why the wall wears down level, or just above, the sole in these feet and remains there, since a proper, calloused sole is made of much tougher stuff than the wall. This may be the reason why feral feet usually aren’t hindered by chipping or cracking flares. Since their feet don’t rely on the wall for support, these exfoliating portions of the wall are never used thusly and so are free to break or wear away without causing damage or undue stress to the rest of the foot or laminae. 

As a result, current thought maintains that the outer wall shouldn’t make ground contact, but rather have a generous “roll” along its outer perimeter (especially at the toe), causing wall-ground contact to be accomplished with the “water line.” Not only does this new vision of the wall challenge conventional practice, and shoeing specifically, it also directly challenges the sharp, even rim around the hoof typically found in equine sculpture. Artists may have to rethink how they sculpt hooves because it appears that a rounded, beveled edge is the correct interpretation, not the sharp, even, crisp rim so typical in sculpture.

More Qualities to Consider

So artists, take heed! The concept of a “good” equine foot is in radical transition, with important implications for sculpture. It doesn’t end there, however! The equine foot should be regarded in nine additional qualities, as follows (in no order):

• Size
• Thickness
• Angle
• Alignment
• Length
• Shape
• Texture
• Breakover 
• Balance

Size 

Foot size should be adequate for the mass of the animal. Note the term “mass,” which is different from “size.” A conditioned halter Quarter Horse has greater mass than a 3-year-old racing Thoroughbred, or a fat pony may have more comparative mass for his feet than a thin Clydesdale. 

Unfortunately, however, foot size is often a casualty of fashion, as many halter horses demonstrate. So be careful when working from references, especially those of halter horses. 

In the past, identifying a foot that was “too small” was rather subjective, but science now has provided a real measurement even artists can use. The equation can be calculated on a calculator, as follows: 

• Measure the circumference at the hairline, right below the coronary band (in inches). 
• Multiply the horse’s weight (in pounds) by 12.56 and hit the “equals” sign. 
• Divide this first number by hairline measurement (in inches) and hit the “equals” sign.
• Divide this number again by the hairline measurement (in inches) and hit the “equals” sign. The answer should be between 68 and 78. If the number is higher than this range, the horse’s mass (or the sculpture’s depicted mass) is too much for the feet.
• Or as the equation: (12.56 x W) ÷ C2 = R

The sum (R) is the ratio of the body size to foot size, described in pounds per square inch. In results, (R) should amount to no more than 78, or 78 pounds per square inch, the maximum loading for an average performance horse (Turner, 2003). Statistically, ratios higher than 78, particularly those higher than 83, tend to develop lameness issues. 

Scaled down, an artist can use this ratio by estimating how many inches her sculpted coronets are and then estimating the weight of her sculpted horse if alive, and then plugging the numbers into the equation. 

Good 

In terms of size, a good hoof has a ratio below the 78 pounds per square inch limit. 

Bad 

Conversely, a bad hoof has a ratio above 78 pounds per square inch. A foot that’s too small cannot withstand impact and loading forces, which is why they’re implicated statistically in many soundness problems, including navicular syndrome. 

One might wonder why the selection for a small hoof has been strong, but perhaps that had to do with aesthetics fueled by the show ring. Indeed, many believe a smaller foot looks “daintier” (as with Arabians) or it makes the body appear more bulky (as in the case with Quarter Horses). However, another reason may be that some people believe a small hoof makes a horse more sure-footed and less likely to stumble, but which clearly is a gross misunderstanding of equine biomechanics.

Artistic mistakes 

Like real horses, many sculptures have feet that are far too small, some of which are taken to extremes of artistic exaggeration. On the other hand, a hoof can be made unrealistically too big, too, as a function of artistic license or over-compensation. Artistic carelessness can also result in different sized feet on a sculpture, which can imply crooked motion, other imbalances, or pathology.

Thickness 

The wall is a complex structure comprised of hierarchal layers evolved to divert or prevent cracks from reaching the sensitive laminae. It’s also designed to deform with each step and then snap back into shape at breakover.

Good 

The wall should be a uniform thickness around the circumference of the distal edge. The healthier the wall becomes, the more uniform the thickness, contradicting the conventional belief that the wall should be thicker at the toe and thinner at the quarters (Ramey, 2003).

Bad 

A problematic wall is one that’s too thin, too thick, or too irregular to serve its function properly.

Artistic mistakes 

When the distal surface is inspected, many sculpted walls are too thin to be healthy, sometimes even having a “knife-edge.” On the other hand, they can be far too thick to be realistic. Most common, however, are sculpted walls that are sculpted carelessly along the distal rim, being uneven and inconsistent rather than uniform. 

Angle 

The question of a “correct” hoof angle is a hot topic. What we do know, however, is that despite what some sources claim, the shoulder angle or dorsal surface of the pastern aren’t accurate means to determine foot angle, a method often recommended by many conformation books. 

Even so, debate exists as to what is the “correct” angle for a foot, and as discussed already, it’s complicated by the wide spectrum of possibilities presented by the feral and barefoot domestic population, or even therapeutic trims, such as the Strasser trim. It may be that there isn’t one right answer, but a spectrum of right answers, dependent on an individual’s conformation and lifestyle. Until science can understand the equine foot better, it’s probably best to proceed cautiously and regard foot angle on an individual basis. 

Good 

As a general rule, the acceptable range of alignment is 54˚- 60˚ for the forefeet and 57˚- 65˚ for the hindfeet. 

David Duckett FWCF maintains that the forefoot’s angle should be about 54˚ and slightly steeper in the hindfoot. The reason being that the dorsal angle of the coffin bone is 45˚ in relation to its ventral angle. Since its orientation in the hoof capsule is elevated in the posterior by about 8˚ - 10˚ (to provide a biomechanical advantage to the tendons in the navicular area), this results in the approximate 54˚ angle. In contrast, the Strasser ideal maintains that the forefoot should be 45˚ (with a coronet at a 105˚ angle to the dorsal wall) and the hindfoot should be 55˚ (with a coronet at a 95˚ to the dorsal wall) because this concept claims the coffin bone should be ground parallel, rather than elevated at the heel.

Bad 

A foot outside the acceptable ranges of alignment. In particular, paired limbs with differing angles is a problem,  such as a clubfoot on one forefoot and a LT–LH on the other forefoot.

Artistic mistakes 

Artists often create paired feet of differing angles, especially in hooves that are raised (on limbs in flight), because they aren’t using protractors to check their sculpting. Indeed, an artist can easily ensure consistent angles between paired feet by measuring the angle between the dorsal angle of the wall and the distal angle of the wall with a protractor.

Alignment 

One would think that “angle” and “alignment” are the same thing. However, while angle regards the foot’s angle to the ground, alignment concerns the foot’s orientation on the bony column. This concept was discussed previously in the Bony Column section, but to add a bit more detail, two aspects are commonly used to determine this aspect for the wall:

• Dorsal-Palmar Balance (DP Balance): This line should bisect the 1^st, 2^nd, and 3^rd phalanges and down through the hoof capsule. The angles of the dorsal and palmar hoof wall should parallel this line, regardless of the actual foot angle. 
• Medial-Lateral Balance (ML Balance): A line should bisect the metacarpal, 1^st, 2^nd, and 3^rd phalanges and down through the hoof capsule to center the foot on the bony column. This ensures that weight and force is distributed evenly. Interestingly, it’s been demonstrated that the functional sole is the same thickness on the ventral side of the coffin bone, which means that it can be used as a guide to measure the ML balance on a real foot (Ovnicek, 2005). For artists, it means that our sculpted soles should be as balanced as our hoof walls.

Good 

All good feet appear to have continuity in DP Balance and ML Balance, suggesting that these alignments are more important than the actual angle of the foot.

Bad 

Deviation in these alignments is associated with nearly all structural lameness and many cases of interference. Typical deviations of DP or ML Balance have been discussed previously in the Bony Column section. 

Artistic  mistakes

DP imbalances are common in sculpture, particularly LT-LH, ESAD, DSLD and Offset axis. ML imbalances also are common, sometimes caused by the artist forcing a hoof to be flush with the “ground” surface, either to compensate for flawed biomechanics or to facilitate the design.

Length 

Hoof length is a real issue nowadays since the feral foot has suggested that nature may have intended a hoof capsule to be far shorter than what conventional theory maintains.

It appears that it’s the thick, calloused sole that pushes the internal structures up from the ground relative to the coronet, thereby allowing the hoof capsule to “drop” to the point at or below the extensor process of the coffin bone, and to wear down to a short toe. However, it also should be noted that some feral specimens sport longer hoof capsules (with accompanying thicker soles) either as an adaptation to a particular lifestyle or to accommodate individual conformation. In particular, feral horses living in marshy environments may have a slightly longer hoof capsule, with accompanying flares and chipping. 

It also should be noted that many horse cousins naturally have longer hoof capsules (and can be higher in the heel, too), such as asses, hemionds, and zebras. 

Good 

Hoof length is measured from the coronet to the toe, and some basic guides are (Turner, 2003):

• 3 inches for an 800 to 900 pound horse
• 3.25 inches for a 950 to 1,050 pound horse
• 3.5-4 inches for a 1,150 to 1,250 pound horse

Note: When sculpting, also keep in mind that hoof length can be regulated by breed registries. For example, the Arabian Registry prohibits a hoof longer than 4 1/2”, including the shoe or pads. It’s also important to remember that hoof length is a function of the individual’s conformation and lifestyle. 

Bad 

A hoof that’s too long creates several problems. For starters, it shifts the hoof capsule forwards, reducing the foot’s base of support which increases unnatural stresses on the foot. By creating a longer lever, a longer hoof also delays breakover and ushers in a host of new problems. 

However, a longer foot can create higher leg action and greater joint flexion, which is why it’s seen often on show horses that need “flashy motion” or why stacks or pads are added. Nonetheless, this situation unnaturally stresses the limb and foot (especially the posterior areas), often resulting in numerous soundness problems. A long hoof also contributes to peripheral loading, a dangerous situation for the foot. A long foot could be the result of mechanical sinking, too, due to a sole routinely pared too thin. 

Overall, feral research has illustrated just how much excess toe is present on domestic feet, which may play a big role in many of the chronic hoof problems in the domestic population. 

Artistic mistakes 

Hoof length is a common problem in sculpture, either because the artist is unaware of the issues involved, or because she’s manipulated foot length so that the piece is stable on a flat surface. Sometimes a sculpture’s hoof length is inconsistent to the registry requirements, if that’s a contextual concern for the sculpture. 

Commonly, however, artists often blindly mimic misguided show ring practices or foot dressing, so we should be skeptical of what we accept at face value.

Shape 

The coffin bone shapes the front half of the foot and the lateral cartilages shape the back half of the foot (but with flexibility). Again, the unchangeable “Duckett’s Dot” is a useful means for artists to evaluate shape (and balance), that point about 3/8” from the tip of a trimmed frog (the center of the coffin bone). 

It’s important to keep in mind, however, that hoof shape can be a product of breed type, too. For example, ponies tend to have narrower and more upright walls while some drafters alternately can have either boxy or “pancaked” hooves. Similarly, Arabians tend to have rounder hooves and many Thoroughbreds are generally wider across the quarters. Yet it must be recognized that it’s difficult to determine if these differing shapes are entirely due to type, or if management plays a role. 

Additionally, how a horse habitually carries himself can affect the shape of his hooves (i.e. does he move crookedly or straight?). For example, a crooked mover, or “leaner” (a horse that favors one side), tends to have mismatched forefeet, usually presenting as one forefoot tending towards LT-LH and the other forefoot tending towards a clubfoot. 

Good 

The foot should have an arch from front to back, much like the arch of our own foot, and be cone-shaped when viewed from the front. As we learned previously, the forefeet are shaped differently from the hindfeet due to the different physical stresses they experience. The paired forefeet and hindfeet should match as closely as circumstance allows (because each foot wears slightly differently, no matter how perfect the limb) and be consistent to limb conformation. 

The wall itself, from the coronet to the ground, should be straight and lack bulges, dishes or flares (dishes are dips at the toe while flares are dips at the sides), unless the “biology” of your sculpture warrants flares or dishes. This also applies to “scooped out” quarters since many feral feet exhibit this trait dependent on habitat (formalized in the “four-point trim”). 

In addition, the distance from the Duckett’s Dot to the outer surface of the medial wall should equal the distance from the Dot to the toe. However, the distance from the Dot to the lateral wall is usually slightly greater than either of these measurements because the medial walls naturally often are steeper than the lateral walls.

Bad 

Deviations away from the symmetry indicated by Duckett’s Dot can indicate problems, such as problematic conformation, improper management, or injury. Common deviations are:

• Wry hoof: When the hoof capsule sweeps to one side, either medially or laterally. Usually caused by an ML imbalance due to poor conformation, crooked motion, pain in the limb (which forces the horse to land unbalanced), or poor riding or management. 
• Flare: Outward distortions of the wall, either medially or laterally, and usually caused by an ML imbalance due to poor conformation, weak hoof walls, or neglect. If forced to bear weight (which is common in domestic feet), flares alter the leg’s flight pattern (since breakover takes the path of least resistance), weakening the hoof and escalating the problem or creating abnormal limb stress and interference. Flares weaken areas of the wall, usually leading to cracks or chips, which is a natural process of exfoliation in the wild foot in certain habitats or during transition between habitats. Flares sometimes occur diagonally as the opposing unflared diagonals are pulled inward with each step.  
• Dish: A dish is a flare at the toe, which is troublesome because it places breakover farther away from the center of the foot and can lead to contracted heels, seedy toe, underrun heels and a LT-LH structure.  
• Bulge: Usually caused by injury or infection, but also by excessive hoof length or lameness in the upper limb (especially the hock). 
• Mulefoot: Similar to a clubfoot, but with narrow, straight walls at the quarters instead of the expected cone-shape, and often accompanied by a frog that’s over-developed. A mulefoot usually is a congenital condition and interferes with foot mechanics, predisposing it to concussion-related lameness and choppy gaits.
• Wide foot: An abnormally wide foot, especially through the quarters, with walls that aren’t upright enough. The heels often are underrun and the sole usually lacks a vaulted structure.  
• Narrow foot: Lacking a conical shape, foot function is compromised (and often associated with navicular syndrome).  
• Sheared heel: When there’s a structural breakdown between the heel bulbs or a tearing of one or both lateral cartilages from their attachments. This will cause the heel to become uneven and asymmetrical, with one heel higher than the other. A horse officially has sheared heels if one heel is .20” higher—almost 1/4”—than the other heel. The affected hoof usually has a displaced coronet, contracted and high heels, a deep cleft between the heel bulbs (with a corresponding one in the frog, predisposing it to thrush infections), a distorted frog, and an upright wall on the affected side (sometimes close to vertical, which can turn inwards and roll under the foot in extreme cases). The corresponding opposite side of the wall usually is longer and has a flare. The laminae in the heel and quarter can also tear and become inflamed. The condition is induced by uneven loading, as a reflection of ML imbalance, or though problematic shoeing or trimming, too (large studs on the outer heel of a shoe, for example, are a common cause). Sheared heels can be associated with the LT–LH foot, too. Sheared heels have been connected to lameness, though not all the time. Nonetheless, the displaced portion of the foot can predispose the foot to cracks, bar fractures, corns and heel soreness. This condition can occur in the forefeet or hindfeet. 
• Asymmetrical hooves: Often caused by crooked motion, crooked limbs, asymmetrical limbs or an injury that creates deviations between paired limbs; the most crooked leg tends to have the smallest, most misshapen hoof. Asymmetrical hooves are difficult to keep sound and require specialized therapeutic treatment.

Artistic mistakes 

Misshapen hooves are common in sculpture, but perhaps the most typical problems are asymmetries, sheared heels, bulges and dishes. Some sculpted hooves are narrow and lack a necessary conical shape.

Texture 

It’s normal for a white chalky, flaky substance to be present around the coronet because that’s the peeling periople. Whether or not a hoof can have small, shallow rings (often called “grass,” “fever,” or “growth” rings) is debatable. Feral hooves usually don’t exhibit them whereas they’re rather common in domestic feet, implying that growth imbalances are present. Indeed, these rings often are attributed to nutritional, seasonal, climatic or systemic changes, and which seem to have a more pronounced effect in the domestic population. 

Perhaps what is of more influence in regard to the presence of rings is the typical structure of the domestic foot in which the outer wall is made to bear weight through peripheral loading. It’s no coincidence that these rings often disappear once the outer wall has been relieved of loading. Nonetheless, many show horses have their hooves sanded smooth and polished to produce a mirror-like finish, which will disguise the presence of rings.

Good 

The wall should be smooth, even and hard, with a waxy appearance. Hooves can be dark (from pigmentation), pale (lack of pigmentation), or striped (alternate pigmentation), and can have many introduced tones from environmental staining, too. If rings are present, they should be shallow and discreet.

Bad 

If growth rings are especially pronounced, they can indicate disease, injury or improper trimming. Likewise, wavy, wide rings, especially at the heel, can signify a laminitic condition. Similarly, thrush, yeast infection, low ringbone, sidebone, abscesses and uneven weight distribution can cause uneven rings. The rings are widest where the growth is greatest. 

Also, there should be no cracks present in the wall. Cracks are referred to by their location, such as toe cracks, heel cracks or quarter cracks. Cracks that begin from the bottom of the hoof are called “grass cracks” and are most common with flares or asymmetrical hooves. Cracks that begin at the coronet are called “sand cracks,” while a “blow-out crack” is a horizontal crack commonly caused by an impact to the wall or injury to the coronet. Interestingly, Bowker has found that injuries to the wall are healed by the inner wall to stabilize the area until it grows out (Bowker 2003). 

Lastly, the wall should be strong and lack any crumbling or weak horn. It also shouldn’t have bumps or divots since they indicate disease or injury. However, remember that chips and grass cracks are typical of barefeet in certain habitats or situations as a function of natural exfoliation, so regard them within the context of the individual’s lifestyle.

Artistic mistakes 

Many sculptures have problematic hoof texture, with pieces often having bumpy surfaces, divots or gouges that depict injury or blow-out cracks. {Note: In paintwork, many artists unwittingly paint in some wall bruising or growth rings that indicate disease, by blindly mimicking what they see in reference photos.] 

Breakover 

Where breakover occurs is important because it affects two pivotal aspects of the limb: (1) It determines if the limb will have the time to land heel-first, and (2) its location determines if the forces will help or hinder the hoof to maintain balance.

Fortunately, by using the Duckett’s Dot, an artist can find the imaginary center of a sculpture’s coffin bone, and then deduce its tip to place breakover correctly on a sculpted foot. When done, this will shape the rest of the foot in turn, essentially building the foot from the “inside out.”

Good 

A foot with a correct location of breakover (and a short toe) has a correctly timed breakover, giving the limb plenty of time to extend and land heel-first. Again, the work of Dave Duckett FWCF is consistent to the findings from feral and domestic barefoot studies: breakover should occur at the point where a line through the centers of rotation of the phalanges pops out of the foot, and that heel support should be at least as far behind the coffin joint as breakover is in front of it. In other words, the distance from breakover to the widest part of the hoof should be shorter than the distance from the widest part to the heel buttresses. 

Likewise, feral feet and sound domestic barefeet demonstrate that the natural point of breakover is over the toe callus (not the toe wall), and within 1” of the apex of the coffin bone, typically about 1/4” from the apex of the coffin bone. This means on an average foot, breakover should be within 1 1/8” - 1 1/4” in front of the frog apex, or about 3/4” back from the toe. 

Bad 

If the toe is too long, breakover is delayed and the leg must shorten the gait in order to have enough time to plant it in the next stride, which is why long hooves usually produce higher flashier action. However, this places unnatural stress on the foot and limb. Delaying breakover also can induce forging since the forefoot doesn’t have enough time to get out of the way for the descending hindleg (which is why so many horses with long hooves need protective boots or corrective shoeing to mediate interference). However, delayed breakover usually results in toe-first landings, which produces a spectrum of serious problems (discussed later).

Artistic mistakes 

Sculptures often have feet with breakover placed too far forward from the coffin bone, which is usually a result of overly long hoof capsules and toes. 

Balance 

Balance is characteristic of a quality, self-maintaining foot because it governs how it responds to the physical forces and the habitat, thereby directly impacting soundness and motion. In short, a balanced foot constantly reachieves balance with each step. Because of this, knowing what a balanced foot looks like has direct relevance to sculpture.

Good 

A feral or sound domestic barefoot is consistent in a specific 1:2 ratio: The distal surface of the foot has 2/3 of its mass behind the frog apex (Duckett’s Dot) and 1/3 of its mass ahead of the frog apex to the point of breakover (not the toe). 

However, it’s been reported that this ratio changes with draft horses (Love, 1998) because a 1:2 ratio can leave too much toe on such large hooves. Instead, draft hooves should have a 1:3 ratio: 3/4 of the hoof’s mass behind the frog apex and 1/4 of its mass ahead of the frog apex to the point of breakover (not the toe).

Bad 

Any deviation from this ratio, or a reversed ratio of 2:1 (of 2/3 of the foot is in front of the frog apex and only 1/3 behind it) means the foot is imbalanced and breakover has been stretched too far ahead of the coffin bone. Such feet not only land toe-first, but also usually stumble and interfere, creating a host of lameness problems.

Artistic mistakes 

Many artists are unaware of this critical ratio and inadvertently end up sculpting feet that resemble the pathological feet on so many domestic horses, i.e. sculpting a foot with too much toe and not enough “back end.” 

Breakover and Landing

Flight patterns are relevant to artwork because a quality foot creates an optimum flight pattern that produces easy, efficient, balanced and interference-free motion, something artists usually want to express in their sculptures. Understanding flight patterns also illuminates much about what a “moving” hoof would be like in stance, which of course is relevant to sculpture.

However, we need to recognize what’s myth and what’s fact. For example, it’s a commonly held belief that artificially trimming the hoof into different angles or lengths can enhance performance. In contrast, research has proven that this kind of manipulation not only fails to deliver on its claims, but also usually creates lameness problems. 

This brings us to the difference between static balance and dynamic balance. Static balance entails the foot in stance (standing square) and dynamic balance regards the foot in motion. How the foot works between stance and motion can be very different. It also means that the limb structure is a factor in shaping the hoof, even if it entails shaping the foot away from “good” static balance to mediate limb conformation, i.e. the more flawed the limb, the more dynamic balance will dominate the shaping of the foot. 

In sculpture, how a foot is dressed in relation to its limb conformation can say a lot about an artist’s knowledge base and attention to detail. Indeed, sculpting a flawed horse may be necessary at some point in our career, but without understanding how these flaws are reflected in the feet and motion means that our piece may not be as convincing as it could be. So pay attention to these details and do homework—remember that the horse’s conformation is expressed in his feet, too.

While a full discussion on flight patterns is a bit beyond the scope of this series (and easily found online and in many books anyway), we’ll turn our attention to perhaps the two most important aspects of a flight pattern when it comes to a quality foot—breakover and landing.

Breakover 

Breakover is defined as the moment when the foot begins to tip forward to lift the heels off the ground at the end of the stride. It’s not when the toe is perpendicular to the ground (as often erroneously illustrated in many resources). In the forefeet, breakover should occur over the sole callus at the toe (previously discussed), and in the hindfeet, breakover should occur just to the inside of the toe. Breakover should be easy, quick and efficient to give the limb plenty of time to achieve a proper heel-first landing.

Landing 

Contemporary research points to a heel-first landing as correct. Specifically, landing flat or slightly heel-first at the walk, and only heel-first at the trot, canter or gallop. Likewise, all quality feet, whether feral or domestic, land heel-first on level surfaces. Heel-first landings allow the limb to fully extend, and just before the heel lands, we’ll see the foot “flip” forwards as all the leg joints go into complete extension, producing a flowing, floating appearance to the gait, like a deer. Thus, the entire limb (especially the pastern bones) is ready for weight bearing because all its joints are fully extended, with no upward curve (or flexion) that must straighten with an abrupt “snap” under loading. 

Landing heel-first is what nature intended because it activates two primary mechanisms designed specifically for impact: (1) The posterior mechanisms in the internal and external palmar foot designed expressly to mediate and transform impact forces, and (2) the proprioceptors in the posterior areas of the palmar foot are stimulated, and in the correct sequence, to coordinate limb motion properly for the next step. This is why heel-first landings are characteristic of sound feet and produce characteristic nimble, sure-footed, efficient motion. It’s also why heel-first landings are the ultimate cure for many lameness problems in the domestic population, including contracted heels, navicular syndrome, and general heel soreness.

In contrast, a bad foot usually will have its toe land first, or have the entire foot land flat with a “thump.” Toe-first landings prevent the foreleg from achieving full extension because there isn’t enough time to get the limb into the correct orientation (which is why toe-first landings are associated with the LT–LH structure, or long hooves, i.e. configurations that delay breakover). The toe touches down first and we’ll see a “wiggle” or “pop” in the pastern as it snaps into a hasty alignment when weight jars it into position. (This “wiggle,” incidentally, inappropriately stresses the ligament that holds the navicular bone in position, causing it to inflame. It’s this inflammation that can be one of the causes of navicular syndrome, and even degradation of the coffin joint.) In short, the forelimb meets the ground in an upward curve (the joints are partially flexed), which abruptly must straighten when loaded, something that the equine limb isn’t designed to do. Predictably, a toe-first landing is devastating to the foot because it circumvents all the mechanisms designed for impact and loading, while forcing all those mechanisms totally ill-equipped for the job to cope with them. Therefore, toe-first landings understandably are linked to a host of foot problems, from those created by uneven wear, excessive and inappropriate impact energies and reduced circulation, and even to various foot distortions or problems up the limb and into the spine. Indeed, Pete Ramey states in his article, The End of White Line Disease (2005), “Achieving a heel first landing is the most important thing a farrier can do for a horse.” 

What compels a toe-first landing? Having an imbalanced foot that’s underdeveloped in the posterior area, both externally and internally. To land heel-first, a foot needs the correct proportional ratio of 1:2 to provide the surface area of the posterior foot necessary. In addition, when improper management creates a foot that’s underdeveloped (internally and externally) in the loading mechanisms at the posterior and palmar aspect of the foot, pain often results and causes the horse to land toe-first. This chronic underdevelopment caused by modern management practices usually is the reason for the general unidentifiable “heel soreness” common in domestic horses, even in those hooves that may appear “good” on the outside. Given that these two deficiencies are the two primary problems in domestic feet, it’s no wonder domestic feet are plagued by so much unsoundness! [Note: For really good pictures of heel-first vs. toe-first landings, visit www.barefoothorse.com/barefoot_Breakover.html]

This does present an artistic conundrum as so often a toe-first landing presents a much prettier picture for a sculpture, or may even be necessary for the stability of a design. Very rarely are heel-first landings able to be used in sculpture. Also, horses don’t always land heel-first, particularly when cavorting or fidgeting, even with the best feet—there's always the “moment” to account for, too. Therefore, each artist must reconcile this issue based on one's own choices, and perhaps it’s possible to use heel-first landings in those works that depict “habitual performance,” and use toe-first landings in those works that represent “a moment in time” pose. Pair that with sculpting quality feet, and artists may be able to work around this design challenge.

Recap

To review what we’ve learned, the commonalities of a “good” foot among feral feet and sound domestic barefeet are as follows:

• They’re adaptable.
• They’re consistent to lifestyle. 
• They’re fully developed and healthy, both externally and internally. 
• Their bony columns are aligned.
• They’re balanced and maintain that balance. 
• They land heel-first with rapid breakover.
• They’re large enough for the mass of the animal.
• The hoof capsules are oriented at or below the extensor process of the coffin bone.
• They have short toes.
• They have thick soles that support weight.
• They're smooth and waxy in appearance.
• The hoof capsule is worn back to the water line.

Knowing how sound domestic feet are like to feral hooves can help guide our sculptural efforts and our interpretation of theories as they develop. The next decade may prove to be an exciting time for equine podiatry, as we learn more about the remarkable and unique biological marvel that is the equine foot.

Exclusive Artistic Flaws

Now it’s time to address problems unique to sculpture, which usually don’t occur with living horses. Let’s face it—because sculptures are the creation of our hands, all manner of mistakes are possible! However, these missteps tend to be the most common:

• Irregular coronets: The coronets on some sculptures can be wildly irregular, alternately undulating up and down or in and out in pronounced curves. Also, ringbone development can be depicted as unrealistically extreme. [Note: In paintwork, a careless hand can lay down pigment of the sculpted coronet onto the hoof.]
• Small frogs: In life, an atrophied frog can become small, but in sculpture, a frog can be sculpted unnaturally small.
• Irregular frogs: The frogs on all four feet aren’t only inconsistent to what constitutes a quality frog, but are also of different qualities. In other words, the artist sculpted the frogs in a slap-dash way without considering how they should be sculpted.
• “One Shoe Fits All”: An artist should consider limb conformation and the “biology” of her sculpture before sculpting the feet—“one shoe” doesn’t fit all feet! Simply using a constant formula for sculpting feet may not be enough to authentically depict an individual, particularly if that sculpture represents one with a rather specific lifestyle. 
• Clone feet: Using pre-casts or sculpting the same kind of foot on all four feet disregarding the obvious physical differences in the shape of the forefeet and the hindfeet. If we cannot tell at a glance which is a forefoot and which is a hindfoot without looking at the sculpture itself, the artist has made a grave error in realism.
• Bucket Feet: Some artists seem to take the desirable concavity of the sole to extremes, creating a foot with a distal surface so deeply recessed within a “tube” of protruding wall that a kind of extruded “bucket” of a hoof is created. In life, this protruding wall would have flared and broken away, or been clipped off by a farrier. Only in sculpture does this foot exist. 
• Stilt Feet: Similar to the Bucket Foot, but instead the palmar foot is present at the distal rim of the hoof. While this could represent a mechanical sinker, the condition usually is so extreme that it goes beyond this to become a form of unrealistic stylization.
• Stiletto Feet: Similar to Stilt feet, this sculptural stylization often is seen in depictions of a show stretch or with extended legs (especially the hindlegs). Here, the heels are lengthened to an extreme in order to get the hoof’s distal surface to be flat with the “ground surface” because the artist doesn’t understand the mechanics of the pastern bones or the structure of a sound foot.

    Sum Up

   Phew! That was quite a lot to digest wasn't it? Yes, there's a lot more to hooves than meets the eye! Knowing how to sculpt accurate and quality feet is a learned skill, one which an artist is best to do earnestly. The payoff is a sculpture that truly rings true, being so faithful to narrative and detail.

   So in the next installment, we'll address perspectives as a final wrap up. Until then, keep that foot in the door!

   "The only person who is educated is the one who has learned how to learn and change."
~ Carl Rogers