Navicular Disease – Part 1: Background

Photo of Coffin Bone with Navicular Bone

It’s a relatively small bone – about the size of a human thumb in the average horse. It bears no direct weight, doesn’t join any other bones together, and is rarely broken. And yet, it’s the alleged culprit in many, many cases of equine lameness. Without a doubt, no part of the equine hoof is as misunderstood, yet subject to incrimination for every bad step a horse takes, as the navicular bone. To quote Dr. James Rooney, the renowned equine pathologist –

Despite thousands, or perhaps millions, of words, navicular disease remains a subject of confusion and error.

There’s been a “method to my madness” in my past three articles (plus The Hoof Landings Tower of Babel, which wasn’t part of the original plan!) entitled The Myth of the Heel-First Landing. In addition to addressing the commonly-held misconception that horses are “designed” to land heel-first, the material was presented to help prepare the reader for coming to terms with the information I’ll be presenting on navicular disease. In this series of three articles, I’m going to attempt to shed some light on the navicular bone and hopefully allay some of the fears the horse owner experiences when he or she hears a diagnosis of “navicular” by the veterinarian. This particular installment will concentrate on an explanation of the role of the navicular bone in support and locomotion, and discuss how and why damage can occur. Part 2 will describe how navicular disease is diagnosed (and misdiagnosed), and the final article will focus on how to treat and/or manage the “navicular” horse.

photo of cutaway hoof

As you can see in the photo at the beginning of this column, and in the above photo of a cutaway cadaver hoof, the navicular bone (A) lies right behind the coffin (pedal) bone (B) and forms part of the coffin joint along with the short pastern (C). You’ll also note the band of grey-white tissue running down the back/bottom surfaces of the bone that connects into the bottom center of the coffin bone. This is the deep digital flexor tendon (D), often abbreviated “DDFT” or simply “DFT,” which is responsible for both helping to stabilize the foot and flexing the foot towards the back of the horse. It also forms part of the “stay apparatus” of the horse – the horse’s suspension. Beneath the DFT is the largest structure in the foot – the fatty-fibrous mass of the digital cushion (E).

The navicular bone is one of three sesamoid bones found in the equine limb – the other two being the pair of small bones at the rear of the fetlock known as the proximal sesamoid bones. The purpose of a sesamoid bone is not to bear weight, but instead to change the direction of the pulling force being applied to a tendon. In this instance, the distal sesamoid bone, or navicular bone, ensures that the pulling force on the bottom of the coffin bone is always from the same direction, regardless of the angle of the pastern bones. Check out the following illustration –

The Role of the Navicular Bone

As you can see, without the navicular bone in place, the direction (and therefore the effective magnitude) of force exerted by the DFT would be highly dependent on the orientation of the long and short pastern bones with respect to the coffin bone. But with the navicular bone acting as a “pulley” to redirect the motion of the DFT, the force on the coffin bone will not change direction when the leg changes position.

So now we have a pulley (the navicular bone) with a rope (the DFT) running across it. Next, consider what Dr. Rooney wrote in Biomechanics of Lameness in Horses about what happens in the foot when the horse lands correctly (i.e. “flat”) –

As the hoof impacts, palmar flexion (rotation) of the coffin joint begins from zero acceleration. If the ground is hard, it will not yield under the hoof impact (will not absorb energy of impact), and the hoof may bounce, hit the ground, bounce again, etc. This bouncing, of course, would not be grossly obvious, but would involve oscillation of the coffin joint by a few millimeters. If the hoof as well as the ground were inelastic, the effect would, of course, be exaggerated. Neither ground nor hoof could yield sufficiently to quickly convert kinetic to potential energy. The energy would remain kinetic, oscillating back and forth between hoof and ground.

For the record: how do I know he’s describing a flat landing in the preceding quotation? The answer is simple: because he states “rotation of the coffin joint begins from zero acceleration.” And the only way that’s possible is if the hoof is contacting the ground flat. So even with a proper landing, there is some amount of vibration (oscillation) of the hoof, relative to the hardness of the landing surface and the inelasticity of the hoof capsule.

In contrast with the equine hoof, there is a considerable body of research on the effects of oscillations on humans’ hands and arms, although there is some dispute over various researchers’ conclusions – largely because differences in the types, frequencies, and durations of exposure used in various studies make analysis difficult. But the symptoms of hand-arm vibration syndrome (HAVS) among people who use various types of vibrating powers tools include destructive joint changes as well as vascular, neural, and muscular problems. In fact, you may be interested to know that it’s considered a serious enough health risk that the limits for vibration exposure for human workers are specified by the International Organization for Standardization (in ISO standard 5349-1)!

In the horse, when the coffin joint oscillates, the deep digital flexor tendon is moving very rapidly and repeatedly across the surface of the navicular bone. Why does that matter? Because when one surface moves rapidly over another surface, the friction between the two generates heating of the surfaces. Think warming cold hands, or starting a fire, by rubbing two things together – same idea. The more rapid and/or more sustained the motion, the higher the resulting temperature. Conversely, with slower and/or less-sustained movement, things don’t get nearly as hot. So, terrain and footwear being equal, a horse that’s moving at low speeds is experiencing less DFT/navicular bone friction, and therefore less heating, than the horse who is moving at higher speeds.

The problem gets much, much worse for the horse who has been trimmed or shod to contact the ground heel- or toe-first. In addition to the lesser amounts of vibration described above, he also experiences very rapid and more prolonged acceleration of the coffin joint at the instant of ground contact, called third-order acceleration, when the hoof “slaps” down as it comes under load. And the more pronounced the heel- or toe-first landing, the more rapid the acceleration and the greater the consequent heating. and landing heel-first or toe-first. That’s pure mechanics: the DFT of the horse who’s landing heel- or toe-first will be sliding farther, longer, and faster across the navicular bone than in a horse who’s landing correctly (flat), even at slower speeds. This is what Dr. Rooney had to say about third-order acceleration resulting from non-zero coffin joint acceleration at the moment of hoof contact i.e. a heel-first or toe-first landing –

In case it has not been said often enough, sudden changes of acceleration cause third-order acceleration, which is vibration: increased friction, turbulence, cavitation, heating, etc. The general case…is that third-order acceleration occurs between the DF and the navicular bone. Vibration, which is third-order acceleration, causes tendon degeneration and navicular arthrosis. The third-order acceleration, in turn, will occur because the coffin joint does not begin rotational movement from zero acceleration.

Sound familiar? It bears a striking resemblance to what’s been well-documented in humans experiencing HAVS, doesn’t it?

So in the simplest terms possible, folks, and in spite of what many people (including many veterinarians) believe, navicular disease is damage to the deep-digital flexor tendon and navicular bone caused by heat, which is caused by repeated heel-first or toe-first landings. In fact, Dr. Rooney, who spent a considerable amount of time researching this subject, reported that he was able to duplicate the physiology of navicular disease (bone and tendon damage) by using an external source of heat on cadaver limbs. Here, then, is an illustration of how and why navicular disease occurs –

The Genesis of Navicular Disease

This is also why feral horses don’t develop navicular disease. As I’ve explained in The Myth of the Heel-First Landing series, the feral horse’s hoof continuously wears itself such that, in general, the hoof (and therefore the coffin joint) does not experience rapid rotation as it makes contact with the ground i.e. it lands “flat.” And because the feral horse lands without the sudden “jerk” that occurs when many of our domestic horses make initial ground contact with the heels or toe and then “slap” the foot down as it comes under load (see the YouTube video accompanying The Hoof Landings Tower of Babel), the navicular bone in the feral horse doesn’t experience nearly as much rapid movement of the DFT across it with every step.

To summarize: whether or not a particular horse will develop navicular disease depends on not just one or two factors, but on a set of conditions that result in enough heating of the area of contact between DFT and navicular bone over a period of time to cause damage. It’s not a matter of any singular event causing the problem, but rather the cumulative effects of repeated “exposure” to vibration, similar to hearing loss or heavy-metal poisoning. All else being equal between horses, those factors include:

  • The degree of front-to-back imbalance in the hoof
    • The more pronounced the heel- or toe-first landing, the greater the distance the DFT travels across the navicular bone, resulting in higher/more-sustained temperatures.
  • The stiffness of the hoof
    • As the inelasticity of the unbalanced hoof increases, the less it can deform to mitigate the forces of impact, resulting in more vibration and consequent higher/more-sustained temperatures.
  • The hardness of the terrain upon which the horse moves
    • Like the stiffness of the hoof, the less the unbalanced hoof is able to penetrate the terrain at the instant of contact, the greater the vibration and resulting higher/more-sustained temperatures.
  • The speed at which the horse moves
    • The faster the horse is moving, the more frequent the coffin-joint rotation, and the greater the buildup of heat.
  • The duration of the horse’s movement
    • As with speed of movement, longer periods of movement of the unbalanced foot will result in higher/more-sustained temperatures.
  • The size of the navicular bone and deep-digital flexor tendon
    • The smaller the size of these structures, the less effectively they can dissipate heat buildup.

Looking at this list should make it apparent why “true” navicular disease (more on that subject later!) rarely occurs in horses that don’t either jump, or trot on paved roads. Those two activities, particularly when coupled with improper hoof care, experience the highest magnitude of (jumpers), and most prolonged (road horses), third-order acceleration of the coffin joint.

I also feel compelled to add that this explanation of the cause of navicular disease is by no means new. Dr. Rooney wrote The Biomechanics of Lameness in 1969! And while that particular book is admittedly quite technical and often difficult to read, both versions of his subsequent book The Lame Horse (1974 and 1998), which are intended more for the horse owner than the veterinarian, also describe this logical, evidence-based theory. Why, then, does there continue to be such a prevalent and profound misunderstanding of the cause of navicular disease among veterinarians, hoof care providers, and horse owners, with its consequent misdiagnoses and illogical “treatments” that cannot possibly succeed?

And that concludes Part 1 of this series! But after reading about the effects of vibration on humans (HAVS), I’m also very curious about whether or not some of the other consequences of vibration, like numbness, may occur in horses as well. Wouldn’t it be interesting to know if, over time, the unbalanced horse was actually losing sensation in his feet, and therefore allowing more damage to occur without his being aware of it?

One more thought to leave you with, which will undoubtedly be good news to many, but bad news for others –

In my experience, the overwhelming majority of horses diagnosed with navicular disease or navicular syndrome do not, in reality, have any issues with their navicular bone or deep-digital flexor tendon.

I’ll explain why I feel confident making that statement, as well as why so many horses are misdiagnosed, when I cover diagnosing navicular disease in the next article in this series.

Till next time…

“A Remarkable Person”

Mary E. "Ginger" Hebrock

Mary E. “Ginger” Kuhn Hebrock 8/26/1934 – 9/14/2015

This Post has nothing directly to do with horses, so you may decide to ignore it. But, as I did for my father John Hebrock and for my best friend Gerald Bremseth, who both passed away in 2013, I must now do for my mother, who left this world on September 14th.

As I’ve often said about horse feet (ok, I did get horses in here!): it’s all about the balance. The same is true of nearly every aspect of life, and, in my life, my mother was in many respects the offsetting force that counterbalanced both my father’s strong drive towards perfection in everything he did, and his admitted lack of patience with anything and anyone that fell short of the mark.

Unfortunately, my father was also a very busy man, so projects around the house would often get started but not finished in any sort of a timely manner – simply because he didn’t have the time to do things exactly right, yet couldn’t bear to do things that weren’t perfect (I, too, suffer from this particular malady). My mother, on the other hand, was far more concerned with getting things done, whether they were perfect or not. A great example of this “difference in styles” could be seen in the main bathroom of the home I grew up in.

In 1962, my parents decided to purchase an unfinished house – the framing was completed, but nothing else – to finish themselves, which involved many, many trips to various lumberyards and supply houses with a trailer in tow. Because the bathroom was fairly narrow, my father spent a great deal of time and effort building a curved vanity with a matching cabinet door so one wouldn’t immediately walk into a sharp corner upon entering the bathroom. He spent hours on that cabinet, trying a wide assortment of construction techniques to achieve a door with an absolutely perfect arc. And the result was, indeed, perfect, and the rest of the bathroom came together quite nicely.

Except for the shelves and molding in the closet. Somehow, finishing them ended up a very low priority for my father, who had moved on to other projects once the rest of the bathroom was in hand. But not for my mother; she wanted the entire bathroom done, so although she’d frequently pester him about finishing, he never managed to return to it. So she finally took matters into her own hands, and cut the remaining pieces of lumber, nailed them up, and painted them. All blunt cuts, mind you – no miters! But it was done. And although my father was furious about her less-than-perfect work, that bathroom was still the same when the house was sold last year – 52 years later!

To be fair: she, too, was a perfectionist when it came to the things she was passionate about. Unlike his largely technical undertakings, my mother leaned heavily towards pursuits involving compassion for those in need. Trained as a registered nurse, she spent her life helping others: working in the pediatric ward of the local hospital, managing the needs of mentally and physically challenged children and adults in a county-run facility, caring for patients during ambulance transport, and other humanitarian efforts. It even extended to more “public” public service: she was the first female Village Trustee and Deputy Mayor of our small town in western NY.

And she had a great sense of humor! When we were kids, our grandmother (her mother) would often sew shirts as birthday or Christmas gifts for my brother and me, which we really enjoyed and appreciated. But shortly before one particular Christmas, my mother very solemnly sat us down to explain that our grandmother had also decided to give us bow ties with our new shirts, which my mother knew we intensely disliked. “Just pretend to be surprised and pleased,” she said. “You don’t want to hurt her feelings, after all.” Over the next days, we worried a lot about those bow ties and how we were going to manage to fool my grandmother into believing we were happy about them. And so, that Christmas morning, when our grandmother handed us the packages containing the shirts and bow ties, we both steeled ourselves to act pleased with the new additions to our wardrobe. And when we opened the boxes, we found our new shirts sporting bow ties…made out of $20 bills! They both had a terrific laugh over that!

But for many, one of her most memorable characteristics was her bright blue eyes, which often seemed to sparkle as if she were enjoying the most pleasant experience in the world that no one else was privy to. I remember seeing them shine many times in my younger days, especially when one of us accomplished something special like earning a good grade or playing an especially good concert. Indeed, her pride in her family and our achievements was always obvious, and shared with anyone who would listen.

Tragically, my mother was robbed of much of her vitality on a dark road one night in December of 1984, when my parents’ car struck the unlit trailer of a log truck a few miles from their home. Although both of them sustained multiple serious injuries in that crash, my mother suffered a head trauma that left her forever physically and emotionally impaired, and hastened the onset of dementia. A stroke in 2008 made things considerably worse, and necessitated her remaining in a nursing facility for the remainder of her life.

Still, she did what she could. Just a couple of years ago, one of the workers in the nursing home mentioned that my mother had been helping her study for her nursing exams, quizzing her on symptoms and treatments for cardiac disease. I wasn’t surprised by the news, because that was my mother – always helping others.

As anyone well-acquainted with my mother certainly knows, there’s a great deal more I could say about her. But this will have to suffice for now. Without a doubt, she touched the lives of many, many people in ways both acknowledged and unknown; as one of her caregivers of the last few years wrote to me, “I’ll miss your mother. She was a remarkable person.” And, along the way, my mother showed me over and over again that having compassion for others, and helping them to the best of one’s abilities, is an honorable and right and rewarding way to live.

I’m eternally grateful for what you so freely gave, mom. I will always miss you, but I’m glad you’ve finally found the peace you so richly deserve.

You were, indeed, a remarkable person…

“The Lesson”

The Lesson - Blank

I had to laugh. One of my clients was recently recounting the resistance she faced from other boarders after making the decision to pursue natural hoof care with me. “And I hope you’re not paying extra for that ‘mustang roll,'” one woman said. “Any farrier can do that!”

Her story ended up coinciding rather nicely with the theme of this particular article. My goal in writing has always been to correctly explain why hoof care based solely on the lessons provided by nature – in other words, “natural” hoof care – is, logically, the only possible approach to caring for every domestic equid’s feet. But a reader’s response to my recent Unnatural Practices article, reinforced by my client’s story, made me realize that my assumption everyone was grasping a very fundamental piece of the hoof care puzzle without my directly stating it was quite probably flawed. After all, you know what they say about assumptions! And that makes this article long overdue, for which I sincerely apologize.

The reader’s comment dealt with the relevance of Jaime Jackson’s observations of the feral mustangs of the U.S. Great Basin to the hooves of her domestic horses – specifically, how she failed to see any. And that’s a very important question that deserves an explanation. Why? Because the apparent differences between feral and domestic horses are often used by skeptics and critics, who really don’t understand how the two are connected, to dismiss the entire concept of natural hoof care outright. And because understanding the answer will also give you insight into a great many things about how our world works. So regardless of what you currently believe to be correct about hoof care, it’s in everyone’s best interest to thoroughly understand the answer to her question.

The Lesson - First

The answer turns out to be remarkably simple; in fact, it can be summed up quite accurately in a single word! But let’s first state the question in a reasonably-complete form –

Question: What do the hooves of the feral horses of the U.S. Great Basin – who live in an arid and abrasive environment; eat dry, bunch grasses and other indigenous plants; and aren’t ridden – have to do with the hooves of my domestic horses – who live in confinement in a much wetter environment; eat various types of hay and processed feeds; and are ridden or driven?

Answer: Everything.

“Ok, Steve,” you’re probably thinking. “Not very helpful. Way too Yoda-esque!” But give me a few minutes, and hopefully you’ll see why I responded as I did.

First, though, permit me to caution you: many of you are going to face genuine difficulties with my explanation because, as humans, we all have certain subjects – usually ones we’re very passionate about or otherwise heavily invested in – we’re unwilling or unable to be objective about because of education, experience, and/or peer pressure. We see and hear what we want and need to see and hear, and close our minds to other possibilities. Close our minds to the idea that we may, in fact, be mistaken. And that’s just human nature; we all view the world through our own set of “glasses.”

This seems to be very much the situation when it comes to challenging traditional points of view in the horse world. For example, when I first began teaching hoof care at the university, students would often ask questions like, “What does this type of horseshoe do?” And I’d answer with, “Well, it’s generally believed that it (fill in the blank), but studies have shown it has no real effect on that particular characteristic.” And then the student would be angry with me, because the data conflicted with his or her view of the world. So I’m well aware of the difficulties with asking people to see things from a new perspective. Nevertheless, I’m going to attempt a clear, thorough, and logical answer; I only ask that you, in turn, attempt to put aside any and all preconceived notions you may have about hooves. And also please remember that I’m trying to help, so don’t shoot the messenger! Here goes…

The traditional view of hoof care, as endorsed by nearly every veterinarian and farrier as well as a great many so-called “natural” hoof care providers, is one based not only on shapes and numbers, as I pointed out in Unnatural Practices, but also – and most significantly – one where hoof form is viewed as the means of causing proper movement. Many volumes have been written on this subject, filling page after page with trimming and shoeing methods that emphasize trimming to particular forms and dimensions for “making” horses move in particular ways or for “correcting” “deficiencies” in conformation and movement. Here are a few examples from The Horse – Second Edition, by J. Warren Evans

In the base-narrow, toe-in fault in foreleg conformation, the foot breaks over and lands on the outside wall, and if the horse is unshod, the outside wall will be worn down. It is necessary to lower the inside wall to level the foot, and then several corrective measures can be used to force the foot to break over the center of the toe.

Horses with a base-wide, toe-out conformation tend to break over and land on the inside toe. The fault is corrected by modifying the shoe to make it difficult for the foot to break over the inside toe but easier to break over the center of the toe.

Cow-hocked horses tend to break over the inside toe and thus place a strain on the inside of the hock….The main objective in correcting the fault is to force the hind foot to break over the center of the toe by braking the inside of the hoof when it lands and rotating the toe inward.

Consequently, this ends up being the usual mindset of the horse owner as well: hoof care providers can and do “create” either good or bad movement by how the hoof is trimmed. So when “natural” hoof care came along, many people (naturally!) applied this same pattern of thinking to it, equating “natural” hoof care with the feral horse hooves’ physical characteristics such as the “mustang roll” or the toe angle. And, because of this type of thinking, they reasonably assumed feral hoof form would not be of benefit to, or perhaps even be harmful to, the desired movement of their domestic horses; hence, the comments of my reader and my client’s fellow boarder.

The problem is – and please listen carefully – the traditional understanding of hooves and hoof care is seriously flawed at its most fundamental level.

So now I’ve said it. And probably many of you can already feel the adrenaline rising as you prepare to argue the point. But please hear me out!

You see, contrary to what you’ve heard or read or thought, “The Lesson” of the feral mustangs is not about the way their hooves look. It’s not about the “mustang roll.” Or how much concavity they have. Or how short their hooves are. It isn’t about any of those things, or any other specific physical characteristic. And yet, it’s also about all of them.

The Lesson - Second

In reality, “The Lesson” of the mustangs we were given through the work of Jaime Jackson is about cause and effect. It’s about understanding that hoof form is merely the effect of several different things, including movement, but is never the cause of correct movement. When we see a group of feral horses, whose hooves have not been shaped by people, we’re seeing the pure product of genetics, diet, stress, conformation, environment, and movement. These factors work in concert to produce the ideal hoof form for that particular horse – without any assistance from us. Indeed, from the moment a foal is first conceived, these elements begin to shape the hoof into its best possible form. And when one or more of those elements changes, such as the horse begins to be ridden, the terrain becomes wetter, or the foal starts walking with the herd, the hoof form will reflect those changes as well. So it makes no difference whether it’s a feral mustang or a domestic grade horse, the forces that determine hoof form are exactly the same for every horse.

And once you come to terms with this list of elements as the only determining elements in hoof form, the next logical conclusion that follows from it is this:

Changing the hoof’s shape cannot possibly change any of the causes of the hoof’s shape.

Look at the list. How could I hope to significantly affect any of them through trimming? Shape doesn’t determine shape – that makes no sense! Does anyone seriously believe, for example, that putting a tire of a particular shape on a bent axle will straighten the axle?  And yet, we blindly buy into the notion that a horse’s conformation or genetics can be altered by changing the shape of his foot.

Why is that?

The Lesson - Third

I realize it’ll probably take a while for all of this to sink in, but the truth of proper hoof care is actually quite simple: we cannot – ever – improve upon a horse’s movement, and therefore his hoof form, beyond what he’s already capable of if he were left to his own devices under suitable circumstances. Period. People can only stand in the way of good movement by creating trimming or shoeing out of harmony with those six elements I mentioned, because those forces are absolutely relentless.

Consider the example of a horse with one front foot more upright than the other: assuming he’s been properly trimmed thus far (admittedly a big assumption), making his hoof angles match through trimming will not accomplish anything, because the forces that caused the more upright foot are still at work and cannot be mitigated through trimming. And so, with every step he takes, his body will be “fighting” the trim, making his movement worse, not better. Think of it like skipping rope: the rope can continue to turn normally only as long as the jumper is in harmony with its movement. But as soon as the two get out of sync – disaster!

The Lesson - Final

So that’s “The Lesson” of the feral mustangs. The “wild horse model” is not about a particular hoof form – it’s really about understanding the forces at work that result in every hoof form. And what they’re teaching us is that the traditional approach, as well as many so-called “natural” methods, espouse hoof care that’s “bass-ackwards,” as my mother used to say!

Proper hoof care, which can only be based on the laws of nature (physics and biomechanics, if you prefer), comes down to having a solid grasp of three things: 1) understanding hoof form cause and effect, 2) understanding what constitutes proper hoof form for a particular horse at a particular moment in the horse’s life, and 3) knowing how to allow that hoof form to emerge by trimming in a manner consistent with the six elements I’ve described. Any other approach can, at best, only impede proper movement and limit your horse’s potential, and, at worst, cause irreparable damage to joints and bones.

Does your hoof care provider understand?

Unnatural Practices

Bell Hoof

The natural hoof is uniform in terms of its fundamental front and hind shapes throughout wild horse society, but it is also uniquely endowed with endless subtle variations in angle, size, and color that set the hooves of one horse off from those of the next.

– Jaime Jackson, The Natural Horse

Back in the “good ol’ days” of natural hoof care, all of us practicing this specialized and then-very-uncommon form of trimming had learned it from its originator: Jaime Jackson. He’d called his technique “natural” hoof care because it duplicated the trim Mother Nature imparted on the feral horses of the U.S. Great Basin, as documented in his book entitled The Natural Horse. And so, applying the term “natural” to Jaime’s hoof trimming process was perfectly logical because the results of his trim were hooves that very closely resembled those of the “wild” mustangs. And horse owners could safely assume the trim their horse received from any one of his certified hoof care providers would be very much the same as the trim they’d get from any other.

Unfortunately, those days of hearing the phrase “natural hoof care” used only for those techniques that yield hoof forms congruous with the forces of nature are clearly behind us. It appears that “natural” is now routinely employed by many to mean practically any trimming style that doesn’t involve horseshoes (and perhaps some that do!), regardless of the fact that most are anything but natural! These alternative trim techniques generally fall into two rather distinct categories: 1) those which use some sort of measurement- and/or template-based approach to trimming without regard for variations in individual hoof form, and 2) those which acknowledge each hoof as an individual, but deviate from natural hoof care practices in one or more aspects of their trimming. And although variations from proper trimming can be extremely problematic and harmful regardless of which group they fall into, this article will focus on the measurement-based techniques.

Whether it’s trimming to specific numbers for characteristics such as toe angle and length, a particular hoof shape, and/or a fixed set of hoof proportions, the mistaken notion that there’s some sort of “universal hoof form,” and therefore a “universal trimming truth” which can be successfully applied to any and all horses, is certainly far from new. For example, Dr. Deb Bennett writes the following about the very influential American “Professor” William Russell and his textbook called Scientific Horseshoeing (7th edition, 1903):

…we find that although there is a correct grasp of anatomy, there is no real concern with maintaining normal feet. There is a concern that masquerades as concern for the horse….Russell’s beautifully engraved plates memorialize engineering ideals, not biological realities. They show perfectly symmetrical hooves being measured with gauges – “proof positive” of the superiority of the scientific approach advocated by the author.

She goes on to add:

Constant observation opens the eyes [of farriers firmly grounded in the biology of the horse] to individual variation and compels them to respond to individual needs, rather than following…a set, “standard,” or mechanical program of trimming and shoeing learned by rote and applied “by the numbers” irrespective of the needs of the individual horse. (“Principles of Equine Orthopedics”, 2003)

So even in 2003, when hoof care providers who specialized in barefoot horses were relatively rare, Dr. Bennett was expressing serious concerns about the increasing popularity of trimming and shoeing methods based on numbers or ideals rather than “the biology of the horse.” Many of those “by the numbers” methods she eschewed have their origins in the work of farriers Dave Duckett and Gene Ovnicek from the latter part of the last century. They (and others) attempted to correlate points on the bottom of the foot with the location and orientation of the foot’s internal structures. Once these points were properly identified, they could allegedly then be used to determine “proper” hoof proportions, toe length, and breakover point by creating a sort of “map” of the bottom of the foot. However, the relationship between internal and external was apparently (but not surprisingly) tenuous, since descriptions of how to locate these reference points often contained lots of words like “usually,” “approximately,” and “typically!”

There’s a simple, logical reason for that: as any scientist or engineer will tell you, no physical characteristic, or set of characteristics, can be described as absolutes. You can only talk about how close to, or distant from, a given size or shape is from “typical.” Measurements of any particular physical characteristic found in nature can be found to follow a curve of normal distribution – a “bell curve” – such as the one superimposed over the hoof shown at the beginning of this article. As an example, let’s look at a summary of Jaime Jackson’s hoof measurements of over 100 feral horses from the U.S. Bureau of Land Management’s Litchfield, CA holding facility –

An examination of this data gives us some useful insight into the difficulties with “template trimming,” starting with the fact that, considering the large number of horse breeds and the often substantial differences between them, 100 or so measurements on a group of feral mustangs is not very likely to be representative of the entire range of hoof sizes and shapes to be found among equines as a species. After all, one typically sees far more variation in animal size and conformation in most boarding barns than in a group of mustangs.

And yet, even given the homogeneity of the sample group, the data in fact shows a surprising amount of variation in hoof measurements! Although it may not be obvious unless you have a working knowledge of statistics, footnote #3 above tells us that approximately 95% of the horses measured fall into the specified ranges. So, for example, the probability that the toe angle of a front hoof – one of the characteristics many “by the numbers” advocates hold to be a constant – will be any particular value can also be more fully described like this –

  • <1% of horses will be less than 48°
  •   2% of horses will be between 48° and 49°
  • 13% of horses will be between 50° and 51°
  • 34% of horses will be between 52° and 54°
  • 34% of horses will be between 55° and 56°
  • 13% of horses will be between 57° and 59°
  •   2% of horses will be between 60° and 62°
  • <1% of horses will be greater than 62°

Quite a range of possibilities, especially given how many people think front hooves should all have the same toe angle! So if your trimmer believes that all front hooves should be, say, 53° but your horse’s actual angle should be 59° – of which there is greater than a 1-in-10 chance of being true – your horse is going to have a pronounced toe-first landing. He’ll therefore not only not be performing at his best, but he’ll also be causing joint damage that will affect his long-term comfort and soundness. And I really need to point out that he has a greater than 66% chance of a toe angle other than the 53° your trimmer thinks he should have. The same concepts hold true for the other measurements as well. And that’s why number- and shape-based techniques ultimately cannot be successful.

And yet, the use of “number-based” and “shape-based” trimming is on the rise, especially among barefoot advocates who also try to sell these as “natural” methods. But if you carefully observe the results of these trim styles, you’ll fairly quickly be able to spot the problems. Two of my favorite examples…

A client asked me to give her my opinion of a YouTube video which showed a woman demonstrating her trimming technique. She carefully measured and drew a series of lines on the bottom of a pony’s hoof, explaining how this “mapping” process determined exactly where to trim the hoof. After a few lines, it became obvious that she couldn’t possibly safely cut the hoof at the places indicated by this method. Nevertheless, she went on to explain that although her method wasn’t going to work on this hoof, it was still the “correct” way to trim hooves.

If a “method” doesn’t work on 100% of hooves, it’s obviously not a viable method.

A clinic participant, who was a “by-the-numbers” trimmer, showed me before and after video of a client horse that was landing acceptably before it was trimmed, but was landing decidedly heel-first after she “correctly” trimmed it. Another example of “method breakdown;” if the horse isn’t landing properly when you’re done, then you didn’t trim it correctly – period.

If the results of a “method” don’t conform to what nature would do, it’s obviously not a natural method.

So why the popularity, particularly when these techniques are so clearly in violation of the evidence provided by nature? A complete answer to that question would probably require an entire book, but I think it comes down to two primary reasons: convenience and fame.

To truly learn something well takes time and (usually) money. Learning is often not easy, and learning to properly trim hooves is no exception. In fact, Dr. Bennett states the following as essential skills for a trimmer or horseshoer in “Principles of Equine Orthopedics”:

  • Training in physical assessment
  • Knowledge of the physiology of body tissues
  • A concept of what is normal in stance
  • Prepared to relate the principles of physics or biomechanics to his work
  • Taught how to develop a long-term treatment plan

This is quite a list, and the prospect of acquiring such an extensive skill set to “just” trim horse hooves would definitely put many people off. After all, you’re talking about a very serious temporal and financial commitment, and the list doesn’t even include the other necessary skills such as tool use and horse handling! It’s so daunting, in fact, that Dr. Bennett believes the overwhelming majority of hoof care providers lack the necessary skills to properly care for horse feet. I won’t repeat the lengthy quotation here, but check out her assessment of providers’ abilities in A Matter of Conscience.

But imagine if, instead, you could just attend a day or two of clinics to learn how to apply a “formula” to trimming that could be used for every horse. Or watch a couple of videos. Wouldn’t that be a whole lot easier and cheaper? And a lot more appealing as well, because people really take comfort in well-defined, step-by-step processes. Kind of like paint-by-numbers rather than art school. But will it still be a masterpiece?

And, human nature seems to be such that many people have a strong desire to be recognized for making some sort of “contribution.” There’s certainly nothing wrong with that. So they change one or more aspects of the natural trim, experience some amount of success with it, and all of a sudden it’s a “new” trimming technique!

Why, you may ask, would they experience successes if their methods are incorrect? For two reasons. First of all, it’s imperative to understand (as I’ve pointed out a number of times in earlier articles) that the vast majority of horses are relatively insensitive to how they’re trimmed in the short term. Will these alternative trims affect their performance? Almost certainly, but if you’ve never felt the performance possible when a horse is correctly trimmed, how would you know? Will it make them lame? Probably not today, but it will affect their long-term comfort and soundness. For most horse owners, though, if their horse isn’t outright lame, they’re content to believe the horse is correctly trimmed. And second, it’s once again a matter of probability: statistically speaking, nearly any trim variation will be correct for some number of horses.

When all of this is considered, it’s easy to understand how and why these techniques continue to surface and gain in popularity. But please remember:

  • By definition, they are not “natural” trimming and should not be promoted as such.
  • Statistically speaking, most of them will work on some horses, but they will not work on all horses.
  • By design, they disregard the uniqueness of each hoof and the causal relationship between conformation & movement and hoof form, instead promoting the incorrect notion that trimming to a specific form or set of measurements will cause proper movement instead of recognizing that hoof form is the consequence of proper movement.

Genuine natural hoof care optimizes hoof function for every hoof as an individual by optimizing hoof form in accordance with the principles demonstrated to us by nature. This can be accomplished only through a solid working knowledge of what constitutes biological normality for the horse, the hoof, and the tissues of the hoof; and the relationship between conformation, movement, and hoof form.

And so, if you’re using a hoof care provider who claims to be practicing “natural” hoof care, please do yourself and your horse a favor and check to make certain he or she is really following the principles nature has repeatedly demonstrated to be correct, and not just reaching for the protractor or the template.

And if you’re a hoof care provider who’s reaching for the protractor or the template, but telling your client you’re providing “natural” hoof care, then shame on you…because you’re not!

Join Us!

Bare hoof

It’s once again time to write a few lines about two exciting upcoming opportunities to study hoof care with Liberated Horsemanship – one of the most comprehensive and highest-quality training programs currently in existence. What really sets this program apart is not only its commitment to absolute adherence to the so-called “wild horse model” based on Jaime Jackson’s observations of the feral horses of the U.S. Great Basin (unlike nearly every other program I’ve encountered), but also its recognition of the importance of a “whole horse” approach to hoof care. Thus, other aspects of equine management such as herd dynamics, nutrition, facilities design, training, and dentistry also play a significant role in their offerings.

I strongly recommend every horse owner attend one of these clinics, regardless of whether or not you’re interested in ultimately trimming horses. Why? Quite simply, because doing so will enable you to identify whether or not your horse is receiving proper hoof care, which the overwhelming majority of horses are not. All you have to do to know that’s true is visit any barn and count the number of foot problems!

Hoof trim clinic in Spain

Hoof trim clinic in Spain

First on the calendar is the European Gateway Clinic being held once again in La Llacuna, Spain from May 18th to May 22nd. This is a great chance to learn hoof care in a stunningly beautiful setting in a quaint village in the mountains of Spain, about an hour’s drive from Barcelona. What’s especially nice about the Spain clinic is not only the opportunity to meet and discuss hoof care and culture with people from many different countries – we’ve had people from Austria, England, France, Germany, Russia, Scotland, Sweden, Spain, and the U.S., so far – but also the occasion to see some spectacular attractions like nearby Montserrat, and Barcelona’s many cultural and entertainment offerings.

Montserrat

Montserrat

Next is the United States Gateway Clinic taking place for the first time in Wooster, Ohio at The Ohio State University Agricultural Technical Institute from June 12th to June 16th. I’m particularly excited about this offering because not only is it on my “home turf,” but because we’re having a special, open-to-the-public event on Friday evening, June 12th, featuring our (OSU ATI’s) two equine professors and myself speaking on three very different and equally absorbing topics! Dr. Karen Wimbush will present the very interesting results of her study on the relationship between the weight of the rider + tack and the horse (which I briefly described in How Much is Too Much?); Dr. Jessica Suagee will give a highly informative talk on the basics of equine nutrition, including understanding hay analysis results and planning a proper diet; and I’ll be discussing the philosophy behind, and advantages of, proper barefoot trimming. Plus, we’re planning some interesting “field trips” during this clinic!

Hoof clinic at ATI

Hoof clinic at ATI

So consider joining us on one of these not-too-frequent, but vitally important, occasions. You’ll find a bunch of like-minded, interesting, and encouraging folks to spend a few days with. And you’ll leave with new friends, great memories, and a whole lot of important knowledge. But sign up soon, because these opportunities won’t last forever…

The Hoof Landings Tower of Babel

Tower of Babel

– with apologies to Athanasius Kircher for modifying his drawing

This isn’t even remotely what I expected to be writing about right now. In authoring my recent series on heel-first landings, I assumed that everyone likely to read them was familiar with the definitions of the various types of landings – probably because what the different landing types are called are, in themselves, accurate descriptions of what happens when the hoof contacts the ground. That seemed like a completely logical assumption, since in my 20+ years of discussing this subject with all types of hoof care providers, horse owners, veterinarians, and students, I’d never encountered a single person who didn’t understand these distinctions.

Until now. For the past several days, I’ve been carrying on an interesting and lively exchange with some hoof care providers on Facebook over what constitutes a “good” landing for a horse, with them insisting that a heel-first contact is healthy and normal. If you’re reading this, you probably already know that I steadfastly believe this to be not only incorrect, but damaging as well. Consequently, we’ve been going round and round, making absolutely no progress at all, until trimmer Dora Libby pointed out that the landings they’ve been observing in a number of videos on YouTube are improperly labeled as showing heel-first landings when they’re very clearly flat landings. So it’s now evident we’ve really been disagreeing over semantics rather than biomechanics!

Yes, this is a big deal. Proper landings are not only a major topic of controversy in the hoof care and horse worlds, but are also very important for the long-term comfort and soundness of your horse, as you’ll see in the upcoming series on navicular disease. So if much of the apparent disagreement “out there” is really a matter of definitions, the first order of business must be to get that straightened out.

The definitions I’ve always used and taught are the same ones Dr. Rooney used in Biomechanics of Lameness in Horses. They’re easy to understand because, as I’ve previously stated, the landing type also describes what happens as the foot contacts the ground. In the front-to-back (A/P) direction, there are three possible ways a hoof can make contact: toe-first, heel-first, and flat.

In a toe-first landing, initial ground contact is with the bottom leading edge (“toe”) of the hoof, followed by a rapid front-to-back rotation of the coffin joint as the foot comes under load, until the heel buttresses (“heels”) contact the ground. Note, by the way, that Jaime Jackson points out in The Natural Horse that toe contact can occur in several different areas of the toe, including a single region directly at the toe, or two regions located symmetrically or asymmetrically about the toe. In my experience, toe-first landings are the least common type, which is fortunate because they’re also the most potentially destructive.

In a heel-first landing, initial ground contact occurs in the opposite order: the rear-most bottom part of the hoof – the heel buttresses – contact the ground first, followed by a rapid back-to-front rotation of the coffin joint as the foot comes under load, until the toe contacts the ground. This is far and away the most common type of landing I see, and trimming or shoeing to accomplish it is the stated objective of many hoof care professionals, veterinarians, and horse owners. But this is also a destructive type of landing, as my upcoming articles on navicular disease will explain.

In a flat landing, the toe region and the heel buttresses contact the ground simultaneously, with no rotation of the coffin joint following ground contact. Note that as pointed out in The Myth of the Heel-First Landing – Part 3, the heels of horses who live on softer terrain will actually penetrate the terrain on ground contact and therefore have no coffin joint rotation as the foot comes under load. This is effectively a flat landing under those conditions, but be aware that the same horse will exhibit a distinct heel-first landing on harder terrain.

Play Image

To help make the differences more obvious, I’ve produced the YouTube video above showing clear examples, in slow motion, of each type of landing, along with a bit of commentary. Please share it with other hoof care providers and horse owners so we’re at least on the same page when it comes to discussing this very important topic!

The Myth of the Heel-First Landing – Part 3

A pronounced heel-first landing in slow motion

Hopefully, Part 1 and Part 2 of this series have laid sufficient groundwork (no pun intended!) for you to now be ready to hear why the feral horse lands flat-footed at the walk. Let’s briefly summarize what we’ve covered so far:

  • As a quadruped, the horse’s anatomy and way of going differs from the bipedal human, and therefore his movement cannot be compared to the movement of the human
  • The human is incapable of seeing small but significant differences in how a horse lands without the aid of slow-motion video
  • Barring injury or other mitigating circumstances, the horse does not actively position his foot for landing
  • The mass of the healthy, properly-trimmed equine foot is fairly evenly distributed front-to-back about the center of coffin joint rotation
  • Any longer part of the hoof wall relative to the rest of the hoof wall will strike the ground first
  • The addition of length or mass can significantly affect the flight arc of the hoof, and, therefore, the way the hoof impacts the ground

And now we need to talk about the effects of movement and terrain on the hoof.

One of the things you may have noticed about your horse, whether he’s shod or barefoot, is that the harder and rougher the terrain he’s used on, the more rapidly his shoes or hooves wear. That’s only logical, since even the steel of a horseshoe is not as hard as many of the minerals present in soil. And given that the typical feral horse travels an average of just under 12 miles per day, it’s no wonder that the constant abrasion results in obvious signs of wear. So if we look at the foot of a feral mustang from a very arid and abrasive environment like the U.S. Great Basin, we see evidence of considerable wear –

A U.S. Great Basin feral Mustang hoof

Note the pronounced rounding of the wall (“mustang roll”) where it contacts the ground, the arch of the foot in the quarters, the blending of the bars and sole into a smooth, polished-looking surface, and the leather-like appearance of the frog. The entire hoof is very short, with the heels worn back to the widest part of the frog.

In contrast, look at the same features on this domestic Ohio horse, whose typical day consists of about half his time in a fairly wet, grass-filled pasture and the other half in a stall, about 6 weeks after his last trim –

A domestic American Quarter Horse hoof

As you’ll note, the wall shows little evidence of wear, with a fairly sharp edge. The arch in the quarters is only evident to the extent that the horse has started to break off excess length in that area in the form of a large chip. The bars are quite a bit higher than the contour of the sole, and the presence of tiny cracks along with the lack of a smooth, shiny appearance suggest that old sole growth has not yet been worn away. The frog has a somewhat “swollen” appearance, and the heels are disproportionately long and therefore well forward of the back of the foot.

These two hooves are rather typical examples at the near-extremes of a continuum of wear, with the consequences of lots of movement over arid, abrasive terrain at one end, and relatively little movement over soft, wet terrain at the other. Keep in mind that the difference in movement between typical feral and domestic horses is tremendous; the domestic horse would have to do 24 laps per day around the perimeter of a 10-acre pasture to equal the distance traveled by a feral horse in the same amount of time!

The relationship between types of terrain and degree of wear was documented by farrier and horseshoe designer Gene Ovnicek. Take a look at this illustration from his book New Hope for Soundness, Second Edition

How environment affects heel length

As you can see, as the terrain becomes softer, the heels experience less wear. But because the heels actually penetrate the softer terrain, the effective toe angle remains essentially constant. Obviously, if you were to stand these three horses on a flat, unyielding surface such as concrete, or move Horses A and B into Horse C’s environment, only Horse C would measure with the same toe angle as he did in his “natural” environment; Horses A and B would have more upright toe angles because of their longer heels. From what we learned in Part 2, therefore, we know that on a flat, unyielding surface, Horse A is unquestionably going to have a more pronounced heel-first landing than Horse B, who will have a more pronounced heel-first landing than Horse C.

This is why so many people erroneously conclude that horses must be designed to land heel-first; very few of our domestic horses both live in desert environments and move as much as feral horses, which makes them much more like Horse A than Horse C. So it’s logical to assume that every horse we’re likely to observe moving over a flat, unyielding surface, including all feral horses except those from environments like Horse C, will land heel-first to one degree or another. But just because that’s what we happen to observe on flat, unyielding surfaces doesn’t mean they’re supposed to land that way on every surface!

The very important point to be made in this discussion lies in the realization that all three horses in the above illustration share a critically-common albeit not obvious characteristic, in spite of the differences in their environment: at the instant of impact, the coffin joint (the joint between the short pastern and the coffin bone) is undergoing no 3rd-order acceleration. Although the foot as a whole is decelerating as it makes contact, the coffin joint is not also rotating at the moment of impact. Any rotation (3rd-order acceleration) of the joint, as we’ll examine in the next installment of this series to be entitled “Navicular Disease – Part 1: Background,” turns out to be an absolutely crucial factor affecting the long-term comfort and soundness of the horse.

Meanwhile, when we consider all this wear happening to the bottom of Horse C’s hoof from miles and miles of travel over highly abrasive ground, isn’t it a logical conclusion that any part of the hoof that was long relative to the rest of the hoof would very quickly be worn off? For example, each front leg of a 1,000-pound horse will have approximately 600 pounds of weight grinding that hoof into the ground with every stride over his entire life. How could it not be worn flat? So Horse C’s coffin joint ends up not rotating because he’s hitting the ground flat; Horse A and Horse B are undergoing no coffin joint rotation because their heels are penetrating the terrain and they’re effectively landing flat.

A beautiful, zero-coffin-joint-rotation landing

A beautiful, zero-coffin-joint-rotation landing

In closing, I’m going to leave you with a couple of statements to consider in preparation for the next article in this series. I truly hope I’ve paved the way for them to be read and understood. But before you read them, I sincerely hope you’ll put aside whatever else you may have heard or read to the contrary on this subject, regardless of where you heard it or whomever said it, and let only common sense and your own experiences – horse and non-horse – guide your thinking. These statements are my inevitable conclusions about landings drawn after a careful analysis of facts over a 20-year period, and I unreservedly stand behind them. They are:

In the feral horse, a heel-first landing is not possible

In the domestic horse, a heel-first landing is not desirable

As I mentioned in Part 1 of this series, the eminent author and equine pathologist Dr. James Rooney – arguably one of the most experienced researchers of the equine limb in the world – also eventually came to these same conclusions. So why is it taking so many others so very long to catch on?

More soon…


ADDENDUM

Following the publication of this article, I’ve had discussions with several people who seem to have not read the entire series of articles, and have therefore misunderstood my two conclusions about landings stated directly above. Therefore, I thought I’d clarify/qualify them a bit more, even though this same information is contained within this and the previous two articles.

Statement 1:

In the feral horse, a heel-first landing is not possible

This statement is predicated on a couple of conditions. First, it is relevant only to a healthy feral horse moving on its flat native terrain at its most common gait (the walk). Although I suspect the same landing happens at faster gaits, I’ve done only a bit of video work at higher speeds, and am therefore not yet comfortable making that statement. Second, as I’ve tried very hard to explain in this article, on softer terrains the heels will appear to strike the ground first, but are actually penetrating the terrain. The net result is that there is no rotation of the coffin joint at the instant of impact; thus, in mechanical terms, they are effectively landing flat. So a heel-first landing, by my definition, is actually a non-zero-coffin-joint-rotation landing. This is the important distinguishing characteristic in a landing.

Statement 2:

In the domestic horse, a heel-first landing is not desirable

Similarly, this statement is really meant to say that a non-zero-coffin-joint-rotation landing is not desirable in the domestic horse. This is applicable when the horse is observed walking on a flat, unyielding surface, and often cannot be seen without the aid of slow-motion video. It can, however, be readily heard on these surfaces because of differences in our auditory, as opposed to our visual, acuity.

Anatomy of a Product Development (“More Fun!”)

Steve & Andy June 2014

First of all, Andero and I want to wish each and every one of you a most joyful holiday season! I wish I’d been able to write this particular article several months ago as planned, but life definitely has a way of proceeding at a pace that’s largely beyond one’s control. In fact, I’d fully intended to finish up the series on proper landings as well as post several other articles I’ve been working on, but instead have spent much of my time this past year working on what I think will prove to be some exciting and useful new products. So things are finally in hand again – if only temporarily 😉 – and perhaps you’ll be able to brighten your own or someone else’s life with the first of those products, which I’m about to describe below…

A few years ago, someone gave me a belt whose buckle was a re-envisioned application of an inexpensive folding hoof pick, which I really liked! I’d already been toying with the idea of creating a belt buckle for the “hoof world,” and the way this particular belt adjusted and fastened inspired me to move forward with the project using a similar technique. That product is now available for purchase here, and I thought I’d introduce it by talking a bit about the entire product development process, which hopefully you’ll find interesting.

Regardless of the type of design I’m working on – electronic, mechanical, software, or aesthetic – most begin with a number of sketches such as the one shown below. In this case, I’m trying to capture the right shape and size for the buckle to evoke the impression a properly-trimmed bare hoof leaves in the sand.

Buckle Sketch

Once I come up with a suitable rough design, I usually switch to the computer to more accurately capture the design intent and start working out the problems. For the buckle, I created a 3D solid model of it in my CAD (computer-aided design) software so I could get a better sense of its proportions as a three-dimensional object and fine-tune its dimensions.

Buckle design in CAD system

There are always issues and potential issues with any new design, and identifying and solving them early on is always preferable to waiting until the design is actually in production. So after finally coming up with a cosmetically-acceptable CAD model, I also verified the design from a structural perspective by subjecting the model to various analyses such as the stress analysis below. In this particular case, I was examining the amount of displacement (“bending”) the finished product, made of brass, would experience if the hook had 20 pound of pulling force applied to it. Note that the maximum amount of bending would occur at the very end of the hook, which would flex only 17 thousandths of an inch!

Displacement with 20 pounds force

The computer is a wonderful tool, but it’s difficult to substitute anything for actually touching and feeling a physical prototype. So I then had several minor dimensional variations of the design 3D printed so I could test the functionality of the buckle with various leather thicknesses.  Once I identified the specific dimensions I wanted, I had a pattern for casting machined, and then off it went to the metal casting company to have the parts made.

3D Printed Buckle Prototypes

As I was finalizing the buckle design and manufacturing, I was also visiting second-hand stores to find used belts I could cut up to make belt prototypes. Once I’d decided on dimensions and belt sizes, I created an engineering drawing for the vendor. And after two or three variations, an acceptable design emerged and the belt was finally done. Thus, a product is born!

Buckle Closeup

All of this took months to get through, and I’m not going to drag this out by giving you the details of locating acceptable vendors and coming up with packaging for the belt. But I will say that more designs are in the works, and include some very useful tools for hoof care as well as other “fashion” designs. All of these products will eventually be found on my new eCommerce site that’s currently in development, but for now you can find a more detailed description of the belt, along with ordering information, here.

Have a wonderful holiday! More articles (I promise!) and products to come in 2015…

Introducing EQUITAG HORSE!

EQUITAGs

It’s been my intention from the beginning of Enlightened Equine to occasionally showcase products and services I believe to be of exceptional value to horse owners and horse care professionals, but thus far I really haven’t done so. However, that’s all about to change as I devote this article to describing what I consider to be an extremely useful product AND service for owners and care providers just introduced by my friend and client Dr. Daniel Michaels. Like us, Danny is a “horse person,” and this product reflects his solid understanding of the horse owner’s wants and needs.

I can’t say for certain, but I suspect we all feel pretty much the same way about our horses. Translation: we spend a lot of time, energy, and money on them, and are therefore always interested in anything that may save any one or more of those. Well, EQUITAG HORSE is just such a product!

Simply put, EQUITAG is a system for managing practically every aspect of your horses’ lives from any smart device. Nearly any horse-relevant information can be stored in EQUITAG‘s online database, and then accessed from your smartphone or tablet. Vaccination records, feed information, favorite photos, training notes, vet appointments, YouTube videos – all of it, and much more, can now be quickly and easily stored in one convenient location. No more digging through files or piles to figure out when your horse’s teeth were last floated!

Equitag Sample Profile

But the real power in Dr. Michaels’ product lies in the way this information can be accessed and shared. When you purchase a subscription (the introductory rate is $44.95/year, or – better still – a lifetime subscription is only $59.95), you’ll also receive a set of EQUITAGs photo-etched with your horse’s unique QR code. These tags, which can be scanned with a free app on any smart device, lead directly to your horse’s own profile page with all of his information, as shown above. The current EQUITAG subscription includes one aluminum stall tag, two aluminum keyring tags (think halter!), and one vinyl trailer (or tack box) tag. So you don’t have to carry those radiographs or Coggins test results with you any more; just scan one of your tags to retrieve them! And, of course, you can always access your profile page through the EQUITAG website via any Internet-connected computer or mobile device.

EQUITAG package

It gets even better. Once your barn manager or other care provider sets up his or her own free EQUITAG caregiver account, he/she then has access to (but cannot modify) all of your information! That means your care provider can verify your current feed or supplement schedule any time, or check when to bring your horse in for your upcoming hoof care appointment. But more importantly, in an emergency situation when minutes may count, he or she has immediate access to all of your horse’s medical information, which may mean the difference between life and death.

And since you can see and share profiles, it’s also a lot of fun! Meet other horse owners with similar interests. Set up people as Friends so you can exchange event information, coordinate training and show schedules, and schedule same-visit vet and massage therapist appointments. Imagine your entire barn equipped with EQUITAGs and simply scanning your stablemates’ tags to know when the dentist will visit!

I sincerely hope you’ll consider simplifying and enriching your “horse life” by adding EQUITAG to your horse’s life; you’ll both be glad you did!

EQUITAG HORSE

How Much is Too Much?

"The Dawn of Reason" cartoon b y Jared Lee

Jared Lee’s cartoon makes light of what is pretty obvious to most of us: the horse is far better equipped to carry people than the other way ’round! And yet, as the size of our population continues to increase, the shrinking weight difference between horse and rider is definitely having an impact on the horse world. For example, one of the owners of the guest ranch I frequent in Arizona (the White Stallion Ranch) told me that although they don’t have an upper weight limit for riders (unlike most guest ranches, by the way), they’ve had to buy increasingly-larger horses to keep up with the changes in guest size. Likewise, my travels to various horse farms have led me to the same undeniable conclusion: there is a growing number of larger riders.

At this point, I realize some of you may be thinking “Oh no! I don’t think I like where this is headed!” But as I’ve mentioned before, my commitment is to the long-term comfort and soundness of the horse. And that includes not only proper hoof care, but nearly every aspect of equine management. So please understand that I’m just delivering information; what you choose to do (or not do) with it is up to you! On we go…

A few years ago, this subject caught the attention of a couple of our equine professors who were interested in finding research in support of some particular method of determining the maximum weight-carrying capability of a horse, particularly the common assertion that a horse should carry no more than 20% of its body weight. But as with many of the horse world’s popularly-held ideas, they found very little actual data to support any specific method or assertion. And so they decided to design a study of their own to investigate the effects of a horse carrying 15%, 20%, 25%, and 30% of its body weight. The resulting paper, entitled “Evaluation of Indicators of Weight-Carrying Ability of Light Riding Horses” (DM Powell et al) was published in the Journal of Equine Veterinary Science (Vol 28, No 1  (2008)). Their publication forms the basis for the information presented in the first part of this article.

I won’t go into great depth on their methodology here, but a brief summary is as follows:

  • Eight fit, mature horses – geldings and mares – of light horse type were used, with feed intake adjusted weekly to maintain initial body weight
  • During the course of the study, the horses were housed individually in stalls, with daily turnout
  • Each horse carried 15%, 20%, 25%, and 30% of their body weight in a series of randomly-assigned trials, with 14-day rest periods between trials
  • After a standardized warmup, each horse performed a standardized exercise test with one of three experienced riders, with the load adjusted by means of lead weights added symmetrically to the saddle
  • Twenty-four hours before and after each exercise test, muscle soreness and tightness changes were evaluated by the same professional animal massage therapist in 40 consistent locations on each horse
  • Blood samples were collected immediately before and after exercise, with additional samples taken 10 minutes, 24 hours, and 48 hours after exercise
  • Heart rate, respiration rate, and rectal temperature were measured immediately before and after exercise

Both the subjective and objective results showed statistically-significant differences indicating greater work rates when the horses carried 25% and 30% of their body weight compared to 15% and 20%. More importantly, when horses carried 30% of their body weight, their serum creatine kinase activity – an indicator of skeletal muscle damage – was elevated immediately after exercise, and remained higher when measured 24 and 48 hours after exercise. So the recommendation that a horse carry no more than 20% of its body weight does, indeed, seem to have some defensible logic behind it!

For heavier riders, then, it might seem logical to use larger horses, right? Well, unfortunately, only to a point, because there’s also arguably an upper limit beyond which a horse’s congenital soundness is in question. Read what Dr. Deb Bennett, noted equine anatomist and author, has to say about equine size and soundness in Principles of Equine Orthopedics

 Before horses were brought into domestication more than 5,000 years ago, the species averaged 13 hands, 2 inches in height and around 800 lbs. Until as late as 1820, horses over 15 hands, 2 inches and about 1100 lbs. were an absolute rarity – and this, by the way, is the maximum size that any wild equine ever attains. Only after the advent of railroad transport did teamsters see an advantage to utilizing cart and carriage horses that were in the 16- to 17-hand range and drafters going as high as 2200 lbs. (And no – despite what you may think you have learned from Hollywood, there were no knightly chargers as big as the modern Shire; the Medieval “Great Horse” stood 14 hands, 2 inches and weighed around 1000 lbs.). The modern Shire is twice as massive as the largest wild equine that ever lived, and the average riding horse which stands 16 hands and weighs 1400 lbs. is itself “pushing the design envelope”….It is sheer foolishness not to recognize massiveness as a significant contributor to abnormalities of the bones, joints, ligaments, tendons, and dentition of modern horses. A good rule of thumb: any horse standing over 16 hands, 2 inches, or weighing in excess of 1450 lbs., is automatically and congenitally unsound for any use involving prolonged trotting, cantering, or jumping. In terms of horseshoeing, even when large horses are used for walk-activities such as pulling wagons or other heavy loads, their massiveness implies a need not merely for correct work but for constant orthopedic prophylaxis or “preventive and supportive medicine.”

Drawing of a mounted knight prepared for battle ca. A.D. 1500 by Albrecht Durer

Drawing of a mounted knight prepared for battle ca. A.D. 1500 by Albrecht Durer. Note the relatively small size of the horse vs. rider, and the evidence of strain on the horse’s back. From Conquerers: The Roots of New World Horsemanship by Dr. Deb Bennett.

Now, I realize some of you may be inclined to argue that certain breeds have denser bones than others, and are therefore better equipped to carry heavier riders. But Dr. Bennett also did some measurements and calculations of bone density using skeletons at the Smithsonian Institution, with the following results:

  • Horses that weighed (in life) 1000 lbs. or less had normal bone density. There was no consistent trend as to breed; they all fell within a single, fairly tight, cluster.
  • Horses that weighed 1500 lbs. or more had below-normal bone density, and although there were a few individual exceptions, the density tended to drop with increasing weight.
  • Horses between these two weights showed a weaker tendency for below-normal bone density. The majority of animals had normal bone density, but there were some which were as low as the lowest in the heavyweight group.

So although some breeds and individuals obviously have larger-diameter bones than others, and are therefore probably better suited to carrying more weight than other breeds, there’s no scientific basis to support the notion that, for a given bone diameter, the bones of a particular breed are stronger than those of another breed. In fact, based on Dr. Bennett’s evidence, one might argue that the less-dense bones of very large horses are probably weaker on a per-inch-diameter basis, in spite of their being bigger.

I also feel compelled to mention two other factors affecting weight-carrying ability:

  •   The horses used in the study were fit horses. So if your horse is out of shape and heavy, it seems logical that some percentage of that excess weight must be deducted from his weight-carrying ability. Because the extra body weight is fairly evenly distributed, it’s probably not the full amount, but I’m willing to bet that it’s at least 50% of the excess amount. For example, if his ideal weight (Body Condition Score of 5) is 1,000 pounds, but he weighs 1,100 pounds instead (Body Condition Score of approximately 6), his weight-carrying ability for rider and tack (assuming a 20% maximum load) would be reduced from 200 pounds to 150 pounds.
  • There’s no weight-carrying “bonus” for riders with good equitation skills, but the poorer the rider, the more of a reduction in weight-carrying ability would seem to be necessary to account for the added weight moving out-of-sync with the horse, which increases peak forces (and therefore strain).

I might also add that although proper foot care is always important for long-term comfort and soundness, Dr. Bennett’s research points out the absolute necessity of it for larger horses. So be certain to use a hoof care provider who not only truly understands the concepts of correct hoof form and function, but who also appreciates the necessity of minimizing unnecessary stresses on these horses’ joints by keeping them barefoot and properly trimmed. That will give your horse the absolute best chance at long-term comfort and soundness.

To help you more quickly determine a given horse’s weight-carrying ability, I’ve created the following charts – in pounds and kilograms – that cover a range of horses from small ponies to those at the upper limit of Dr. Bennett’s recommendation –

Graph of weight-carrying ability of light riding horses in pounds

Chart in pounds

Graph of weight-carrying ability of light riding horses (kg)

Chart in kilograms

I’ve also put printable versions of the charts here (pounds) and here (kilograms), so print one out and hang it in your barn. But don’t be too surprised if it makes some people uncomfortable! For our horses’ sake, it would be far better if we were all “in the green,” but I realize a great many of us are not. So please carefully consider what’s best for all concerned parties. And keep in mind that one fairly simple solution for many riders may be to get rid of that 40-pound Western saddle!

Meanwhile, guess I’d better think about doing away with the Fanta…