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I’m taking a quick break from the Hoof Angles series to comment on a very serious problem with the way we manage our horses: excessive caloric intake. Because of the unusually warm weather we’ve been experiencing here in Ohio, the pastures are especially lush right now. And with that lush grass comes a greatly-increased risk of laminitis and founder – the #2 killer of horses.

Yes, I know what you’re thinking: “My horse has been out on grass pasture his entire life, and he’s never had a problem!” But that’s the same logic people use to rationalize all sorts of destructive behaviors. The odds may have favored your horse in the past, but, overall, they’re against him. And that’s a fact based on data, not just my opinion. I also realize it’s the “horseperson’s dream” to finally own a few acres so he or she can keep their horses on grass without having to buy hay. But it’s simply not good for them, any more than a steady diet of glazed doughnuts is good for you and me.

Last year I wrote a post entitled Laminitis Risk Calculator that included an MS Excel spreadsheet to help you assess whether or not your horse is at risk. That spreadsheet is still available, either under Tools in the Sidebar, or through the aforementioned post, and I strongly encourage you to download the file and do a thorough analysis of your horse’s needs and current consumption. This year I decided to try to make the data more readily understood by creating a pair of charts that will allow you to quickly approximate your horse’s daily caloric requirements versus his intake.

The first chart, labeled Daily Caloric Requirements, will let you quickly approximate your horse’s daily needs by locating his desired weight along the bottom, following it up until it intersects with the type of work he’s doing, and then noting the calories required on the left. Remember that the work times are averages, and adjust accordingly. And if you want a more accurate estimate of your horse’s weight than a weight tape provides, see the Instructions page of the Laminitis Risk Calculator for a method based on girth and body length.

Once you’ve determined his requirements, use the second chart, labeled Daily Caloric Intake, to figure out how many calories he’s currently consuming. The items that are typically fed “all at once” (hay and feed) are listed as flat lines per indicated weight on the chart, while grass consumption is shown on a per-hour basis, with and without a grazing muzzle. Don’t forget to multiply the hay and feed numbers by the amounts actually fed. Look up the number of hours on pasture along the bottom, follow it up until it intersects the appropriate sloping grass line, and note the calories on the left. Then, add in the calories from hay and feed, and compare the total with his needs. If it’s higher (or possibly lower), you need to make an adjustment! Note that treats and supplements aren’t included, so consider them as well. And be honest about it; there’s no point in pretending he’s working more than he is, or eating less than he is, just to make the numbers look better. Let’s do an example…

Suppose I have a 900-pound horse whose weight is pretty close to ideal, and I ride her for 45 minutes Tuesdays and Thursdays, and 2 hours on Saturdays and Sundays. That’s a total of 5-1/2 hours per week, or an average of 47 minutes per day. So according to the first chart, her work load is Light and her average daily caloric need is 16,000 calories. She’s out on the pasture for 7 hours every day (with no muzzle), and I give her 20 pounds of grass hay each evening and no feed. That means she’s consuming just over 15,000 calories of grass plus (8,000 x 2) = 16,000 calories of hay each day – nearly twice the number of calories necessary to maintain her weight! So it’s time to make some adjustments. I could cut her hay in half (8,000 calories) and cut her pasture time down to a bit over 2 hours (8,000 calories), and that would be very close. But, being a big fan of keeping horses outside, I’d rather put a muzzle on her (3,800 calories) and cut her hay to 15 pounds per day (12,000 calories). There are lots of ways to end up with the correct diet, and the Laminitis Risk Calculator makes it easy. But you can do a pretty good job with these 2 charts.

For more information on laminitis, be sure to check out the Animal Health Foundation. They have a lot of very useful and interesting information on this all-too-common condition. And remember: the risk of laminitis is very real, and you need to take it seriously! So please share this with your friends and stablemates.

I’ve added a button to make it easy to print both the charts –

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Back to hoof angles soon…

“I cannot end  the story of the horse without writing with regret that the health of this useful and precious animal has been up to now surrendered to the care and practice, often blind, of people without knowledge and without qualification.” – Georges-Louis Leclerc (1707-1778)

Leclerc De Buffon was a French naturalist known for his comprehensive writings on natural history. He ended his zoological description of the horse with the preceding quotation, which, sadly, is still very much the case. For example, I attended a presentation at the Equine Affaire last weekend that was a mixture of good anatomy and bad advice concerning what a horseshoe can and cannot do for the horse. And a number of the presenter’s comments were directly relevant to the subject of this post: the relationship between the internal structures of the hoof and the external hoof wall.

Let’s start by talking about what matters to the horse. After all, he’s the real beneficiary (or victim) of hoof care. First and foremost, he doesn’t care about what his foot looks like; he cares only about how it functions. And the point of departure for proper function is correct alignment of the bones of the lower limb, as shown in the accompanying illustration.

However, I want to point out three things about this image before I continue. First, it’s not quite correct; the bottom rim of the coffin bone isn’t really parallel to the ground. Rather, it forms about a 3° angle with respect to the bearing surface. Second, they haven’t labeled the navicular bone – that tiny bone directly behind the short pastern/coffin joint. And third, note that in this lateral (side) view, the “front” of the bones (not counting the navicular bone, of course) are roughly in line with each other.

This last observation is the source of the difficulty, and the logic behind it goes like this:

1. From the side, the “front” of the hoof wall is parallel to the “front” of the coffin bone, and,
2. In a properly-trimmed hoof, the bones of the lower limb line up; therefore,
3. If the angle of the “front” of the hoof wall matches the angle of the “front” of the pastern bones, the hoof must be properly trimmed.

The flaw in this train of thought lies mainly with the first item, because the statement is true only for a 100% healthy and properly-trimmed hoof. It’s a misconception that the dorsal hoof wall necessarily accurately reflects the position of the coffin bone inside the hoof capsule. Many, many horses have some degree of thickening of the dorsal hoof wall due to long-term imbalances coupled with bad farriery practices, and so that relationship will no longer hold true. Even a slight amount of thickening will affect the angle read on a hoof gauge by several degrees. And that’s in an otherwise-healthy horse; in the laminitic horse where the white line has stretched to one extent or another (particularly at the toe), the angle discrepancy between the dorsal hoof wall and the coffin bone can be anything from a few degrees to dozens of degrees. Take a look at these radiographs –

Which one would you want your farrier to use? If you’re 100% certain your horse’s hoof is like the one on the upper left, things would probably be fine. But the upper-right hoof is pretty typical-looking in appearance, yet the radiograph reveals a 5° discrepancy between the hoof wall and coffin bone. That means if your farrier uses this horse’s wall as a reference, he/she is going to “rotate” the coffin bone  5° out of alignment, causing an imbalance in the tendon and ligament tensions.

From here, it only gets worse. While fairly long, the hoof in the lower-left radiograph has a smooth-looking hoof, which means many farriers and vets would attempt to match the hoof-pastern angle, leaving the heels too long with respect to the toe and/or wedging up the heels with a shoe/wedge pad. The result? A horse with a misalignment of 15°! Then, when the horse starts having heel pain (because he’s pounding down on his heels), someone will eventually x-ray the horse and declare the coffin bone is “rotated” 15°. The horse can’t win!

Remember – the horse doesn’t care what his foot looks like. He cares only about how it functions. And bone/joint misalignment means he’s not going to function as well as he could. The lower-right image shows a laminitic horse with at least three distinct hoof angles. Which should your farrier follow?

As I’ve mentioned in the past, I’m a big fan of much (but not, I hasten to note, all) of what Dr. Deb Bennett has to say about hooves. I like the following illustration and quotation from her Principles of Equine Orthopedics. In the quotation, she’s rendering her opinion of a particular “method” of trimming based on proportions of the hoof (Russell) –

“If you want to cordially make yourself insane, try analyzing proportions in horses’ feet. It is a very slippery business. Because the pastern and ankle are driven to take on whatever angle they have by the shape and angle of the hoof capsule, this “ideal” from Russell is just that — one possibility out of many theoretically possible. Particularly, I am critical of the idea that the toe of the hoof should line up perfectly with the pastern axis. I think this can happen but is not in fact the relationship most likely to keep most horses sound….The pastern angle must never be used as a basis for predicting the “proper” angle of the hoof….The toe must not be trimmed to parallel the line of the pasterns. It may – or may not – wind up there after the fact.”

This is why trimming methods based on lengths and angles and numbers of any sort can’t possibly work. The only way to ensure the foot will be properly balanced is to use the bottom of the foot – with an accompanying comprehensive understanding of the characteristics of the various tissues present – as the singular guide for trimming. Armed with that knowledge, every foot you trim will always be correct!

More later…

In Hoof Angles – Part 1 we touched on the basic parameters of movement that veterinarians and farriers attempt to alter through trimming and shoeing. In this installment, we’ll examine a fundamental misconception about cause and effect as it relates to equine anatomy: the notion that the shape of the hoof causes the horse to move in a particular way. This idea, in fact, is so basic and so prevalent that it impacts nearly every aspect of traditional hoof care. And this applies not only to deliberate manipulation of front-to-back balance i.e. hoof angles, but to side-to-side balance as well. Just look at any book on horseshoeing or so-called “corrective” farriery for detailed procedures on straightening crooked limbs and altering movement patterns through trimming and shoeing. Page through a horseshoe catalog and you’ll see dozens of shoe styles that reflect this belief: wedge shoes, shoes with long branches (“trailers”), shoes with beveled or rounded toes, asymmetrical shoes, shoes for specific breeds…the list goes on and on. For example, look at this pair of photos from Bud Beaston’s The Master Farrier –

These shoes are custom made with the intent of addressing specific movement issues. The ones on the left are for American Quarter Horses, and the ones on the right are for American Saddlebreds.

As I stated earlier, the underlying premise for all of this is that movement can be positively influenced by what happens on the bottom of the hoof. But the reality is this: hoof form is the consequence of how the horse moves, not the cause – at least not in any positive way. Let’s examine why, using a simple but easily-understood example: the construction of the front axle for my new car –

Yes, I realize this isn’t a perfect analogy, since a horse’s limb motion is reciprocating while wheels are rotary. But it’s actually closer than you might initially think because the objective of both situations is the same: efficient horizontal movement. To quote Dr. James Rooney in Biomechanics of Lameness in Horses –

For efficient locomotion, vertical movement (lifting the body against the force of gravity) should be reduced to a minimum in favor of straight-line, forward movement….Since the vertical movement of one leg is nearly balanced by the vertical movement of the next leg in the gait sequence (down and up, respectively), the net effect approaches pure horizontal motion.

And that, after all, is the goal. Just like my car, we want the horse to move forward with minimal resistance (maximum efficiency), and anything that impedes motion detracts from the objective. For example, suppose my tires have an extra lump of rubber on them –

For a while, at least, I’m going to have a bumpy ride! The lump on the tire causes resistance to horizontal motion because it forces the car to literally lift itself (vertically) as it goes over the lump. But because the rubber is softer than the road, the abrasiveness of the road will eventually wear off the lump and the tire will be round. The movement of the car causes the shape of the tire, not the other way around!

A horse’s hoof is exactly the same. Anything on the hoof that prevents efficient movement creates extra work for the horse to overcome. But given sufficient time on abrasive terrain, the barefoot horse will wear off whatever is resisting motion, just like the car’s movement wears the lump off the tire. That, by the way, isn’t the case if the horse is shod, or if I make my tires out of titanium –

A shod horse is essentially “stuck” with whatever the farrier did, because any chance at self-correction has been defeated by the metal shoe. But the situation is often much worse for horses. Let’s look at another wheel –

While the lumpy tire certainly makes the ride rough, the lump is fairly small and fairly smooth, so it doesn’t place a lot of additional stress on the axle joints. With this tire, however, there’s quite a bit more stress on the joints as the wheel rolls onto the flattened area. The weight of the car literally “snaps” the wheel down, only to have to work extra hard to lift the weight of the car up again as it rolls past the flattened spot.

Many horses endure a similar situation because, I suspect, people think the horse somehow corrects his landing according to what’s been done to the bottom of his foot. But that’s not the case. As I say to clients, “When you wear high heels, do you really think your foot somehow ‘knows’ the heel is longer and corrects the flight arc for a proper landing?” Of course not. In fact, after examining horses in which the extensor, deep flexor, and superficial flexor tendons, as well as their respective check ligaments, had been severed, Dr. Rooney makes the following point about hoof placement –

On the basis of these observations it seems quite clear that alignment and placement of the pastern and hoof can be carried out passively with virtually no active muscular assistance. The contention is not that the muscles are inactive or useless, but rather that their primary function is not production of movement.

In other words, when the structures many believe actively place the hoof at landing are cut, the horse still lands the same way! So the horse is not controlling how he lands; therefore, if one part of the hoof is left long relative to the rest of the hoof, it’s going to make contact with the ground first. And when the horse’s weight comes down on the hoof, it’s going to snap the rest of the foot down. That so-called unilateral concussion and consequent “snapping” motion are extremely destructive to the horse, which we’ll discuss in a later post.

I hope you’re beginning to understand that the forces at work on the hoof are absolutely relentless, constantly at work reshaping it to permit the horse to land and break over with minimal resistance with every step. Just as I can’t change the basic forward motion of the car by changing the tire, the forces shaping the hoof aren’t altered by manipulations at the ground level because motion doesn’t originate at the ground. So anything you do that resists a minimal-impact landing and a minimal-resistance breakover can only be negative; you can’t improve the motion of the horse beyond his conformation, but you certainly can cause long- and short-term damage to joints and soft tissues, depending on the nature, location, and extent of the “resistance” you force upon the horse’s hooves.

As I like to say, a hoof care provider has, in reality, only two choices: he or she can either help the horse achieve that minimal-resistance landing and breakover, which requires an acknowledgement of any shortcomings in the horse’s conformation, or he/she can stand in the way of long- and short-term comfort and soundness by deliberately or inadvertently departing from proper balance.

I choose the former.

Until next time, I’ll leave you with a couple more photos of my car – this time adjusted so the wheels are no longer parallel. Let me know what kind of tires you think will make them parallel again…

NOTE: This particular subject is of great interest to me because its exploration leads the logical person  to question the very foundations of modern farriery. Foolishly, I began the writing process thinking I could say what needed to be said in a single post. But after I started putting my thoughts down, it quickly became evident there was no way I could accomplish what I’d set out to do with only one post. And so I’ll be presenting it as a series of articles instead, beginning with some anatomical and biomechanical background theory and concluding with the consequences of artificially manipulating hoof angles.

—

One of the most commonly misunderstood topics with respect to equine hooves is the subject of hoof angles. When hoof care professionals speak of “hoof angles,” they’re referring to the angle the dorsal hoof wall (at the toe) forms with respect to the ground, as shown in the following photo/diagram –

As I mentioned in Off His Rocker(s), many horse people place a great deal of emphasis on hoof angles. Owners think a particular angle is important for proper movement, or that the angles of hoof pairs must always match. Veterinarians and farriers are forever trying to enhance movement or increase comfort by deliberately manipulating hoof angles, which is accomplished by adjusting the relative amounts of bearing surface hoof wall at the toe and heel buttresses (“heels”) and/or by utilizing wedge shoes and/or wedge pads. Adding (or not removing) length at the toe relative to the heels will lower the angle, while (more commonly) adding or not removing length at the heels will increase the hoof angle. And yet, these angles are not arbitrary. As you’ll learn, there is only one correct angle for every horse’s hoof, and artificially varying that angle is not without consequences. But more on that later; we’ll spend the rest of this post covering some necessary background information and relevant terminology.

If you click below on what appears to be a tiny strip, you’ll see it’s actually a series of 33 sequential frames extracted from my upcoming video on hoof landings. In the leftmost frame, the horse’s front left hoof has just made contact with the ground, and in the rightmost frame, the front left hoof has finished one complete stride and once again made ground contact –

The distance traveled along the ground from one end of the photos to the other is defined as the horse’s stride length. For any particular hoof, one stride consists of two parts: the support phase (also called the stance phase), where the limb is bearing weight (shown in the first 2o images), and the swing phase, where the hoof has left contact with the ground and is in flight (shown in frames 21 through 33). If we were to then tape a light to the horse’s front hoof and view the path the light traces as the hoof leaves the ground and then lands, the result would look like the following composite photo/diagram –

This path is known as the flight arc. Note there are several interesting things we can learn from this photo. First, the flight arc is fairly shallow, with no large excursion off the ground. This, of course, varies with the breed and conformation of the horse, but like many other horses, this horse has much more forward motion than vertical height apparent in the flight arc. Second, you’ll see that the gentle peak in the flight arc occurs soon after the hoof leaves the ground. And third, notice that the rear hoof’s contact point with the ground is slightly past where the front foot began its flight.

The next sequence of photos from the same upcoming video shows a (different) properly-trimmed horse at the walk. The top set is the landing and takeoff of a front foot, while the bottom set is a rear foot. To save space, I’ve put a break in the sequence between when the foot finally lands and when it again begins its rotation off the ground, evidenced by the radically different angles of the cannon bones –

Notice how smoothly the hoof lands – perfectly flat – and then leaves the ground. The breakover (time) is the time difference between when the heels leave the ground (frame 7 in the top sequence) and when the toe leaves the ground (frame 9 in the top sequence).

Keep in mind that it’s not possible to calculate exact times and positions from these video excerpts because each frame is 1/30 of a second apart, and motion has occurred in between the captured images. Another interesting phenomenon apparent in these video stills is the blurring due to motion, most prominent when the hoof is farthest from the ground. That’s because the hoof decelerates to near zero as it prepares to make contact, and accelerates again as it moves higher in the flight arc.

Let’s now look at what determines the “parallelness” of the pairs of limbs i.e. whether or not the horse’s toes point directly forward, or whether they turn out or turn in. Interestingly, the plane defined by a limb’s motion is determined not by the joints of the lower limb, but by the construction of the horse’s shoulder or hip. I particularly like this illustration from Dr. Deb Bennett’s Principles of Equine Orthopedics –

The reason for identifying these particular movement parameters is because these are the characteristics veterinarians and farriers endeavor to change through trimming and shoeing: the stride length, the flight arc, the landing, breakover time, and the plane of limb movement. Most of these are thought to be connected directly or indirectly with hoof angles. Over the next few posts, we’ll examine whether or not these connections are real, and see what the data actually tells us about changing, or attempting to change, these gait characteristics.

In closing, let me share yet another video excerpt with you; this time of the landing and takeoff of a horse who happens to be shod –

Unlike the previous two examples, you’ll see this horse literally “slams” his feet down, even at the walk. And most importantly: this bad landing cannot be detected under normal viewing conditions. To the eye, this horse appears to land perfectly fine; it’s only when capture the movement on video and slow it down do we see just how bad this landing really is. Think about the implications of that next time someone tries to convince you that you should see a horse land heel-first!

Stay tuned…

 

This is one of the real joys of my life – sharing knowledge with others. After some prodding from various clients, coupled with a student from the far east coast of Canada coming to study with me, I’m happy to announce that I’ll be offering two clinics in May. And it’s useful to know that once you’ve attended a particular clinic, you may attend that same clinic in the future at no cost (other than materials and lunch). If you’re attending for the second (or third or fourth) time, however, please contact me so I know to expect you.

Special Topics/Advanced Trimming

(NOTE: This all-day clinic is the one I present as part of Liberated Horsemanship’s hoof trimming training program in Warrenton, MO – a program I highly recommend for those interested in learning more about not only hooves, but other equally-important aspects of equine management as well. Be sure to check out their website for a schedule of their Gateway Clinics, which feature some outstanding equine professionals.)

Intended for the experienced hoof care professional, the first part of this dual-themed clinic challenges the audience to realign their approach to several of the equine world’s firmly-held beliefs and practices about horses and horse management, and equips them with the knowledge and tools necessary to present science-based alternatives. In the second part, the clinic familiarizes participants with the underlying anatomy and bio-mechanical theory necessary to successfully trim the abnormal hooves associated with certain pathological conditions such as severe laminitis, injury, and chronic imbalance, in accordance with natural hoof care principles. Large-screen live video is utilized to provide an unobstructed view of all clinic materials. Each attendee receives a booklet containing assessment and course of action information, including high-quality color photographs and radiographs of abnormal hooves.

Date:           Saturday, May 5th, 2012

Time:          9AM – 5PM

Location:    OSU Agricultural Technical Institute, Wooster, OH

FAQ Sheet:  Click Here

Cost:           $300 (materials & lunch incl.)

Register:     Click Here

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Understanding Natural Hoof Care

Given the overwhelming amount of information available to today’s horse owner, making well-informed decisions about hoof care can be a daunting undertaking for those interested in both short-term performance and long-term sound­ness. When facing abnormal conditions such as laminitis or navicular disease, the challenges are even greater, and the horse owner can suddenly find himself/herself at the mercy of conflicting advice from well-meaning veterinarians, farriers, and other horse owners.

Through the use of large-screen live video and other visual aids, this lecture/clinic presents anat­omy, biomechanics, and hoof care theory in a comprehensible and logical format that will equip the horse owner with the information necessary to make informed decisions based on fact, not sup­position. For those desiring a more intimate look at the actual trim experience in anticipation of further education, or just wanting to “get their hands dirty,” the clinic continues with a descrip­tion of tools & tool use, the step-by-step process of natural hoof trimming, and hands-on guided in­struction through the natural trim process using cadaver hooves.

Date:           Saturday, May 12th, 2012

Time:          9AM – 5PM (lecture portion ’til 2PM)

Location:    OSU Agricultural Technical Institute, Wooster, OH

FAQ Sheet:  Click Here

Cost:           $300 (materials & lunch incl., cadaver hooves extra)                             $75 lecture only (materials & lunch incl.)

Register:     Click Here

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