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WHAT IS A HEALTHY HOOF AND WHAT DOES IT LOOK LIKE?


Part 1: Healthy horn

The wall horn

The white line horn

The bar horn

The sole horn

The frog horn

The periople horn

Connection of the coffin bone with the hoof capsule




Part 2: The Shape of the Hoof

General Considerations and View from the Side

View from the Front

The Shape when viewed from the sole

The view of and from the heel area



WHAT IS A HEALTHY HOOF AND WHAT DOES IT LOOK LIKE?


If you are not already familiar with the basic anatomy and function of the hoof, please read first Anatomy and Function of the Hoof. This will help you to better understand this following article.


When we speak of healthy hooves, we usually think about a perfect image of a hoof or at least functional hooves.

However, there is no such thing as a perfect hoof. Just like in humans, horses’ feet differ vastly from horse to horse. There may be the perfect hoof for the individual horse, meaning the horn is healthy, the connection with the coffin bone is tight and strong, the balance of the hoof matches the rest of the horse’s body and allows for maximum movement, and the size of the hoof is ample for the size of the horse. But that specific hoof might not be at all perfect for another horse.

And a functional hoof may serve the horse, but must not necessarily be healthy throughout or be optimal for the horse.

In addition, hooves change all the time: be it because of the weather, the time of year, the diet or the amount of exercise.


In order to know what healthy means, we also need to know what is not healthy. Since there exist a whole lot more unhealthy feet than healthy ones, one has a wide field of study available. Also, because so many horses have unhealthy feet, they are often regarded as the norm and not recognized as unhealthy.

In this article I will show some unhealthy feet, but for an in-depth discussion please go to this link Unhealthy Hooves.


Healthy horn:


There are different kinds of horn to consider:


The wall horn


Healthy wall horn is smooth, growth rings are hardly visible, it has a natural and shiny coating almost looking a bit like lacquer (this coating is usually absent in very abrasive terrain). There are no chips or cracks visible, and all horn tubules run in a straight line parallel toward the ground.

The outer wall horn is produced by the coronary band, where live papillae keep producing horn around themselves which is then cemented together by intertubular horn. These horn tubules are very visible to the naked eye. The outermost layer of the wall is the most strong and dense part of the wall as it contains a larger number of tubules. The further toward the white line, the fewer the tubules and the softer and weaker the horn. This is a very important feature, as the outside of the wall protects against the environment, while the softer inner wall can flex and give and accommodate the somewhat flexible connection with the coffin bone.

The inner wall horn is produced by the lamellae that also produce the white line horn. As the outer wall grows down from the top, the inner wall constantly grows from the lamellae outward and joins the outer wall horn. To my knowledge, nobody as of yet fully understands how this process works. It is an incredible engineering feat.


Fig. 1 shows the healthy shine of the hoof surface. Also observe the smoothness of the wall and the arrangement of the horn tubules, which is very easy to see due to the coloration of this hoof. The toe wall is perfectly straight, the heels are short and fully supportive of the back part of the foot.



Fig. 1



Fig. 2 shows a rough terrain hoof. Notice how worn the surface of the hoof capsule is. Also note how far up the wall has been abraded into a strong mustang roll. This feature is not apparent in Fig. 1 as that hoof only traverses turf and hard road surfaces. This also is a very healthy and strong looking foot.


Fig. 2



Figure 3 shows very unhealthy wall horn with lots of growth rings, the entire hoof capsule is pulled forward and there is a pronounced toe flare. Also note how “empty” the area looks right above the heels and the entire coronary band as compared to the hooves in the photos above. This means that the entire inside support structure – coffin joint and lateral cartilages- has sunk down into the hoof capsule. Healthy feet have very pronounced lateral cartilages palpable above the hairline of the heel areas and the area around the coronary band feels like a plump and firm bulge.


Fig. 3




In a healthy hoof, the thickness of the wall is adequate all the way around the hoof capsule. In strong wall horn, the outer wall or pigmented wall is quite thick in comparison to the inner and unpigmented wall. In white hooves, this transition is often hard to tell, however.

Donkeys tend to have no unpigmented wall at all.




Fig. 4

This hoof demonstrates average wall thickness of a domestic hoof. Inner and outer wall are hard to tell apart, esp. as part of the outer wall has been rounded off into a moderate mustang roll.


Fig. 4



Fig. 5

On a black hoof inner and outer wall are much easier to tell apart, although on this hoof as well some of the outer wall was rounded off. But the inner wall is quite thick (except in the quarters where it is very thin due to flares, a definite weakness ), indicating that this horn is not at optimum strength.


Fig. 5




Fig. 6 shows a donkey hoof that had been very badly neglected, and this is the first trim. But you can see that the wall that remained after restoring some balance to the foot is all pigmented.


Fig. 6




When viewed from the bottom, the wall horn has no holes or cracks and appears dense and smooth.


Figure 7 demonstrates perfect wall horn when viewed from the bottom. This hoof is from a dead mustang, untouched by man. Under frog horn, I will comment on the strange appearance of this frog.


Fig. 7




The white line horn


The white line really is not white at all, it is usually a cream or yellowish color. It is much less dense than wall horn as it is made up of the horny lamellae produced by the laminar corium. A healthy white line is extremely narrow, not much over 1/16th of an inch, is uniform in color and is tightly connected to the sole and wall horn. Usually one can judge a white line only during trimming. As soon as the wall grows out, the white line horn can look much more distorted, and the color is often not visible.


Figure 8 shows a trimmed cadaver hoof. The white line is not as tight as it should be, and you can see that in this hoof, it varies in color. The more orangey color in the toe area most likely was caused by trauma from a too long toe.


Fig. 8


Fig. 9a and 9b show what tight white lines usually look like in a recently trimmed hoof or a hoof that keeps itself trimmed at this level. See also Fig. 7 for a healthy white line in a self-maintained hoof.


Fig. 9a

Fig. 9b


Fig. 10 shows another cadaver hoof that had a shoe on prior to trimming. The white line appears yellowish in this picture. It appears to be very tight in the heel areas, more stretched in the toe area. Note the incredible damage that nails do to the horn. This hoof has been over-trimmed intentionally, too much wall, frog and sole has been removed, but I wanted to follow the damage up into the live horn.


Fig. 10



Fig. 11 shows the foot from fig. 10 trimmed into the corium. Note how deep the damage goes. The black areas are dead live lamellae.


Fig. 11



The bar horn    Types of Horn


Bar horn is really wall horn and has the same characteristics, although bar horn tends to be less thick than wall horn. Important to know is that bars end where their corium ends, about half way down the frog. When properly trimmed, one can discern thickness of the bar and its white line. The bars should be straight throughout, not curved like in figures 4 and 5. A curved appearing bar needs to be trimmed until it appears straight. If you look closely in fig. 10, the trimmed cadaver hoof, you can see the white line of the bar.


Fig. 12 shows the bottom of a cadaver hoof with the sole removed. One can clearly see the live lamellae of the bar, running in a straight line.


Fig. 12



Fig. 13 shows a hoof with naturally wearing bars that do not require trimming, although it could be trimmed some to totally remove the bar from the sole, esp. on the right side. (Note: the pinkish color in the sole is caused by too much pressure from snow- and ice packing. It is definitely bruising, but horses never seem to be bothered by it. By the time this color appears, the insult has been about 3 month prior)


Fig. 13



Fig. 14 shows a hoof that demonstrates the natural crack that develops at the end of a bar when it grows too long. While the bar on the left is ending at its proper length, the bar on the right continues past the crack.


Fig. 14



Fig. 15 shows the same foot with both bars trimmed. The “white” line of the bars is now visible, and the excess length of bar has been trimmed off the sole. At the end of the bar on the right you can still see the remnant of the crack. That bar could also use a tad more straightening which would be accomplished by trimming off a little more off the top of the bar horn.


Fig. 15



Fig. 16 shows a hoof with extremely overgrown bars. The natural breaks are circled. Note how the bars “mushroomed” over the sole. This causes great discomfort to the horse by bruising the sole, and inhibits proper sole growth in the process.


Fig. 16





The sole horn


Healthy sole horn of what is called the live sole plane appears smooth and uniform in color, except for hooves that have a pigmentation pattern like striped hooves (see Fig. 4, this is also a very healthy looking sole). Sole keeps shedding constantly, and dead sole manifests as a cracked layer which covers the live sole plane. Depending on terrain, amount of movement and frequency of trimming, there may be a lot of dead sole accumulated or none at all. Flaky sole horn may also be due to fungal disease. Trimming down to the live sole is sometimes needed to figure out the actual health of the sole horn.


Sole horn grows from the sole corium, from papillae similar to the wall horn. Sole horn is a much softer material than wall horn, its consistency can be compared to hard rubber. The horn tubules are sometimes visible like little pores on the sole surface. If you look closely at Fig. 12, you can see that pattern in the remnants of the sole. It is usually hard to see on the surface of the live sole, as the tubules get smashed down and laid over. In the same figure, you can also discern the live sole papillae, esp. on the left edge of the coffin bone.


Fig. 17 shows a very healthy live sole without dead sole accumulation, except that the bars are overlaying the sole a bit too much, esp. the one on the right. On the left bar you can clearly see the natural bar break. On the right it is barely visible. The juncture between sole and frog is plainly visible, a sure indicator that no extra sole is accumulated.


Fig. 17




Fig. 18 shows a sole with some dead sole accumulation as indicated by the somewhat cracked looking appearance. Note the bar break on the right side and the excess bar horn below the brake.


Fig. 18




Fig. 19 shows a hoof with lots of dead sole accumulation. This kind of dead sole buildup, its consistency somewhat crumbly, is often noticed on horses who live/work on very harsh terrain and in hot climates.

Nobody is really sure yet if this accumulation is produced to protect the live sole, or if it could/should be removed by trimming. Personally I think one should leave this sole intact to protect the sole from very hot ground. In colder climates I would suggest to remove it.

Note the depth of the collateral grooves as they continue around the tip of the frog. This depth indicates the thickness of the dead sole buildup, as live sole always joins the frog at the very bottom of this groove. See Fig. 17 for this. Whenever this junction of sole and frog in the front half of the frog is not visible, there is some dead sole buildup. Often we see a “dirtline” next to the frog as an indicator. Fig. 18 has such a crease around the front half of the frog, although it is very clean on this hoof.

Also note the straight bars that do end where they should. This is a self trimming, hard working hoof.


Fig. 19



Fig. 20 shows another hoof with lots of sole buildup. The difference here is that the bars are also very overgrown, and the sole material is extremely hard. This horse also lives in a dry and hot climate. This type of sole buildup happens quite frequently there. This horse was more comfortable after removing this sole, and of course the excess bars, which may have been a lot more bothersome than the sole to begin with.


Fig. 20





The frog horn    Top    Types of Horn


Healthy frog horn is like hard rubber, very resilient but strong, and very difficult to pierce with a sharp object. Often one needs to trim a bit off to determine if the horn is truly healthy as the frog keeps shedding an often rough and frayed appearing layer. Healthy frogs can have lots of different appearances depending on moisture content, amount of movement and the terrain the horse is living/working on.

It can appear leathery and textured, or rubbery and totally smooth, may look very plump or a little shriveled, and it may have different colors.

For an in depth discussion of the frog, please go to this link Health and Disease of the Equine Frog


Fig. 21 depicts one of Cheryl Henderson’s great collages that shows the anatomy of frog. The frog grows from papillae just like the sole. You can see those in the bottom left picture of the collage, sort of looking like fronds.

The strange pattern of the frog in Fig. 7 is caused by those horn tubules bunching together and laying over. This type of frog can be observed on horses in arid climates, but also on very young horses (see Fig. 22)


Fig. 21



Fig. 22 shows another collage of Cheryl’s which demonstrates the development of the frog tubules from baby feet on. She says that they often lay backwards from the apex and forward from the heel area.


Fig. 22



Figure 23 shows a hoof of a live horse in Spain. On this hoof, even the sole tubules got bunched up and layed over.


Fig. 23




The periople horn


The periople is a thin layer of horn, produced by the perioplic corium. This corium is very thin, only about 1 mm thick, and consists of many fine papillae. It is located right at the top of the coronary band corium which produces the outer wall, and continues as the bulbar corium toward the heels which in turn produces the bulb horn.


Fig. 24 shows a hoof with the capsule removed. You can see the laminar corium, coronary corium and at the very top of it, really not visible as such, the perioplic corium.


Fig.24




In Fig. 21 you can see how the perioplic horn joins into the bulb horn. The periople usually appears to be a little rough, reaching down about an inch or less from the coronary band. When wet, it can swell on and look quite prominent, when dry it can be hardly visible. It can be at times totally invisible, abraded by rough grass etc. like in Fig. 2.


Fig. 25 shows a very common appearance of the periople horn.


Fig. 25





Connection of the hoof capsule with the coffin bone


The hoof capsule is meant to protect the inner structures of the hoof, the coffin bone, the coffin joint and all soft tissues like ligaments, tendons, nerves and blood vessels. The hoof capsule is produced by the coronary corium, the lamellar corium, the bar corium, the sole and frog corium.

Through the lamellar corium, it is tightly connected with the coffin bone and in healthy hooves is practically mirroring its shape. In Fig. 24 you can see a part of the coffin bone exposed beneath the lamellae. When viewed from the side, the coffin bone does not reach all the way back into the heel area, this area is filled in by the lateral cartilages. Fig. 26 gives an idea of this.


Fig. 26



Fig. 27 shows an empty hoof capsule on the bottom of the picture and its contents on the top.


Fig. 27





The connection of capsule and coffin bone is extremely tight and strong, and the coffin bone is literally suspended by this. But this connection is also very vulnerable to mechanical forces or disease which can pry it apart, with the result that the coffin bone begins to rest on the sole. For more details please see Anatomy and Function of the Hoof.



The Shape of the Hoof       Top


General considerations and view from the side:


The shape of the hoof can give a good deal of information regarding the health of the foot, but lots of factors play into this, and I most likely could fill a whole book and still would not cover all possible scenarios.


I will try to limit myself to the most commonly observed landmarks. Largely, the shape of the hoof is determined by the shape of the coffin bone in roughly the front two thirds of the foot (up to its widest part) and the health of the lateral cartilages and the frog in the back third. Also, the height of the foot is determined by the height of the coffin bone. Although we do want and of course need ample horn protection of this bone, we do not want excess, as the hoof capsule is cone shaped, and any extra material past the sole must necessarily apply lever forces against its own structure, be it in the toe, quarters or heels.


There are about as many different coffin bone shapes as there are hooves, no two hooves are totally alike, and additionally shape is dependent on age, breed, shoeing- and trimming practices, disease, amount of movement and the conformation of the horse’s limbs and body, as this often causes one-sided pressure on the hooves and manifests in steeper or more flaring walls.

Coffin bones are really very small in relation to the size of the skeleton, and they easily deform under pressure, never being able to return to their original shape. While a healthy coffin bone appears triangular when viewed from all angles, this shape can easily get distorted. Also, front coffin bones usually have less concavity than hind coffin bones, but even that fact can get turned around at times by very poor balance, neglect or disease.


Fig. 28 shows coffin bones from hind feet


Fig. 28





Fig. 29 shows the same bones viewed from the solar surface


Fig. 29



Fig. 30 shows coffin bones from front feet


Fig. 30



Fig. 31 shows the solar surface of front coffin bones


Fig. 31



While truly healthy and non-disfigured coffin bones can give very reliable and consistent information about the health of a foot, not too many horses are blessed with this advantage. But even a somewhat disfigured coffin bone still can reside in an otherwise healthy foot and serve the horse well. The shape of the hoof may no longer be “perfect” to our standards, but the horse is just fine with it.



Fig. 32 shows a cross-section of a healthy looking cadaver hoof, prepared by Allie Hayes from http://horsescience.com/ where the hoof wall perfectly matches the shape of the coffin bone.


Fig. 32



Fig. 33 shows another specimen of Allie’s where the wall does not mirror the bone at all. This is quite obviously not a healthy hoof.


Fig. 33



Fig. 34 shows deformed coffin bones (not that the previously shown coffin bones were perfect!!) Note how the one on the left begins triangular and abruptly ends in (on the picture) a vertical line.

The one in the middle is oval, with the right palmar process actually turning toward the inside, and the one on the right is somewhat triangular on the right but on the left it is almost a vertical line (again, on the picture of course) toward the back.


Fig. 34



Fig. 35 shows that coffin bones can also deform at the solar surface. Poor suspension of the coffin bone causes it to sit on the sole, and as the hoof constantly tries to stay functional, the bone demineralizes under pressure and keeps the horse in effect “sound”. A healthy coffin bone sits totally level on the ground all the way around.


Fig. 35





As much as coffin bones differ in shape, they hardly differ in height. Draft horse coffin bones are not much taller than those of lighter horses, and most of the latter are of approx. the same height, independent of the horses’ height and weight.


Fig. 36 shows an array of front coffin bones, with a draft horse on the left and an immature pony on the right. Note that most of the coffin bones have some degree of deformation in the toe area.


Fig. 36



Given the consistency in height of the coffin bone, we can conclude that too long and/or too tall a hoof capsule cannot be a sign of good health, and we can train our eye quite quickly to this factor. There is however still the variant of how high within the hoof capsule the coffin bone is placed. Usually, the very top of the coffin bone, the extensor process, sits about 6 to 8 mm below the top of the coronary band. In wild horses, it is placed often higher, allowing for a shorter hoof capsule. In diseased hooves, it is often placed lower, a condition that is called “ too much distal descent” of the coffin bone. (Pete Ramey wrote a wonderful article about that. Go to this link http://www.hoofrehab.com/jessica.htm for reading.)


Fig. 37 shows a radiograph of a hoof.

This coffin bone seems in an appropriate position height-wise, although it is hard to tell because the coronary band is not clearly marked in this picture. Most veterinarians fail to do that.


Fig. 37



Also, the angle at the toe is fairly consistent throughout the horse world. Around 45 degrees for the front coffin bones and 50 for the hinds.


Fig. 38 shows a front and hind coffin bone. The difference in angle is well visible here. But not all horses have so much difference between front and hind.


Fig. 38



Fig. 39 shows an array of hind coffin bones, both from the front and the side


Fig. 39





I have a whole collection of coffin bones, and among those, about 80% fall into these measurements. But I also have quite a number of fronts measuring around 40 degrees and hinds around 45. Donkeys have steeper bone angles, and many mules as well. How do I know which ones are from front or hind hooves? I cannot be 100% sure with the deformed ones, but in general front coffin bones are rounder in the toe area, have a shallower angle at the toe and less concavity on the bottom (See Fig. 30 and 31). Hind coffin bones are more triangular in the toe area, have a steeper toe angle and more concavity (See Fig. 28 and 29).


I have 5 horses, and 4 of them measure between 48 and 50 degrees at the center of the toe wall in the front feet, and between 53 and 55 behind. The fifth one measures 44 in the front and 49 behind. Considering that the coffin bone should be slightly elevated in its back part- the palmar processes - by about 3 degrees (some experts say 5) , 4 of my horses range within the norm, the fifth one is a bit more unusual.


There is quite a debate whether the coffin bone should be elevated in the back at a standstill with all feet loaded equally, or if it should be ground parallel. In Fig. 37 you can see a ground parallel coffin bone. Personally, I am convinced that it needs to be elevated, because when the horse is putting more weight onto the coffin joint during exercise impact, this joint and with it the back part of the coffin bone get pushed down into the hoof capsule, into the digital cushion. If the coffin bone is already parallel to the ground before the impact this part of the hoof, the quarter, has nowhere to go but hit the ground hard. Dr. Chris Pollitt’s video –“ Foot Studies” (fascinating video, highly recommended) – shows this process very clearly.


What one can conclude from the above is that a very important criterion for assessing health is the fact that healthy front hooves have a shallower angle than hind hooves. This is an extremely important factor for the horse’s overall balance, and is very often violated by allowing heels in the front growing too tall, assuming this will reduce the strain on the flexor tendons. What it really accomplishes, though, is a slackening of the deep flexor tendon, and as the horse cannot adjust tendon length, it adjusts its stance to put tension back into the flexor system. This is accomplished by standing further back with the front legs than normal, normal being in the vertical. In order to regain overall balance, the horse now needs to bring his hind legs further forward which puts too much pressure on his hind heels and allows toes to grow too much forward and/or too tall, over time resulting in crushed heels and too much toe and thus in a backward tipped coffin bone. The tell-tale convex “bullnose” is frequently observed, but sometimes walls can appear straight, albeit at a very low angle.


Fig. 40 shows hind feet with crushed heels and too much toe. The ‘bullnose’ is more pronounced on the left hind. On the x-ray of the LH one can clearly see how the coffin bone is tipped backward.


Fig. 40




High heels in front are usually seen in conjunction with too much toe length, which puts tremendous strain on the toe wall/coffin bone connection as the horse is now tipped too much onto his toes, often resulting in a dished shape of the toe wall, indicating separation of coffin bone and wall. Breakover of the toe wall should take place where an imaginary continued line of the coffin bone would contact the ground. In Fig. 41 one can see that this location would be well back from the existing toe wall. The shoe that this horse is wearing is supposed to help with the breakover, but from experience I know that this does not work. The toe wall gets jammed up against the shoe and continues to grow too long, increasing the problem by exacerbating the stress between coffin bone and wall. Also this type of shoe shape exerts tremendous pressure onto the quarter area of the hoof, an area that nature had designed not to carry much weight (the heels and the ‘pillars’ of the toe area are designed for this, see Fig. 66 ). I once had leased out a barefoot mare, and after two years she was returned to me as hostile and aggressive, and very uncooperative. She had exactly this kind of shoeing job in front, and her soles were actually bulging beneath the coffin bone. Of course I immediately removed the shoes and the horse breathed an enormous sigh of relief and soon returned to her previous docile personality.


Fig. 41 shows high heels and a dished toe. The x-ray confirms too much toe and gradual separation in the toe wall. If this condition is allowed to persist, the horse can founder mechanically.


Fig. 41




High heels can also result in under-run heels, putting enormous leverage onto the quarter walls of the hoof and the area of the navicular bone. The actual heel height (note: height is different from length!!) is decreased by long under-run heels again, so those horses, when shoed, usually receive wedge pads to raise the toe angle, a practice which tends to crush the heels even more and perpetuates the forward running toe which will result in a compromised coffin bone connection and “flat- and thin soled” horses who “need” shoes.


Fig. 42 shows a shoed hoof with severely under-run heels (left), and the same hoof after shoe removal (right). The heels should be back at the widest part of the frog. More about this later.


Fig. 42



As this article is supposed to explore what healthy hooves look like, it is high time to show some healthy images again. But I hope you agree with me that it is also very important to understand what is not healthy, and why.

It is difficult to portray a whole horse true to nature with a camera as the lens distorts to some degree. This becomes esp. evident with hoof angles. In the following pictures, the angles of the horses’ hooves are not totally true to nature, but I think one can clearly see that the hinds are steeper than the fronts. What is also visible is that the hind pastern have a steeper slope than the front pastern. This goes along with the hoof angles and is extremely important for the horse’s locomotion. The front legs are designed to take up weight, the hind legs are designed for propulsion.


Fig. 43 The heels appear high in the front due to the angle of the camera. As the horse turns his front feet out a bit, the shot is not directly from the side.



Fig. 44, the same horse from Fig. 43 in closeup.






Fig. 45 The front heels appear a bit too high here as well, but in reality are not. You can see a close up of the left front in Fig. 1.




Fig. 46, the same horse from Fig. 45 in closeup.





Fig. 47 another set of legs that demonstrates well the different angles of the hooves and pastern. This is the same horse as in Fig. 51.




Hoof shape also needs to be considered from other viewpoints. While we are at the side view, the orientation of the coronary band toward the ground can give very accurate information about the position of the coffin bone. After much observation and measuring, it has been determined that a slope of approx. 30 degrees indicates a correct front to back positioning of the coffin bone inside the hoof capsule. A camera can of course quite distort this angle, depending on the positioning of the lens. In order to get an accurate picture, it needs to be taken from ground level at 90 degrees center of the hoof.

When viewed directly from the side, coronary bands should look totally straight. ( when the camera angle is off just a little, they can appear curved, but poorly balanced hooves also present with curved coronary bands, as can hooves with an old injury).

UPDATE
I never felt quite comfortable accepting the 30 degree rule for the coronary band as gospel, but it was so widely accepted that I used it as a guide line myself. Dr. Strasser was the first to come up with this theory, and it supposedly always indicates a ground parallel coffin bone in all equids. As I did no longer believe that a ground parallel coffin bone at a standstill was helpful for the horse, except in foundered feet, I assumed that a hairline of about 27 degrees would be a good insurance that the coffin bone had a positive palmar angle of 2 to 3 degrees. I kept scouring the internet for x-rays that confirmed this theory, but nobody ever seemed to do both: take x-rays and measure the hairline. So I bit the bullet and spent some money on this. I had 2 or 3 hooves x-rayed on my 5 horses, front and hind. The results were amazing. While 4 horses measured 27 degrees all the way around and one 25 in the fronts, the position of the coffin bone was all over the place. Some were ground parallel, some elevated from 2 to about 5 degrees, and 2 hinds were actually almost negative plane. I need to state here that I did not trim to the hairline angle, I rarely ever measured it. I trimmed by live sole plane and toe angles and overall balance of the leg. It was coincidental that the hairline angles matched so closely. I also saw x-rays from a foundered horse where the hairline was about 31 degrees or so (hard to measure as it was not straight) but P3 was still elevated by several degrees.

CONCLUSION:
while a close to 30 degree hairline is a good first indicator to evaluate hoof balance, in order to know for sure one needs to take radiographs.

Fig. 48 shows an example on how to apply this principle.


Fig. 48



In Fig. 49 this line is clearly more horizontal, indicating too-high heels and a coffin bone tipped too far to the front, in spite of the apparent shallow hoof angle. An x-ray would reveal a situation quite similar to Fig. 41 although the hoof has a totally different shape on the outside.


Fig. 49



Although the picture of Fig. 50 (which is also Fig. 40) is not of good quality, one can clearly see how much steeper this coronary band is than the ones in the previous 2 pictures, and the radiograph in Fig. 40 proves the theory by demonstrating the tipped back position of the bone.






We covered toe angles, toe height and position of the coffin bone as revealed by the slope of the coronary band, so the next landmark to check is the frontal view.


View from the front :       Shape


When viewed from the front, healthy hooves appear quite short in height (the camera angle can cause lots of distortion again), the coronary band looks totally horizontal and straight, and the side walls are more or less angled toward the ground, but are quite straight without noticeable flares.


Fig. 51 shows 2 different hoof shapes on the same horse which is very common. Note the straight walls, (the ones on the RF – left in the photo – more upright) the even height of both feet and the horizontal and straight coronary bands – a little hard to see with all the hair.


Fig. 51



Fig. 52 shows much more sloping side walls, but they are straight and again, a horizontal coronary band. Note that this hoof is not centered below the leg.


Fig. 52



Fig. 53 shows a hind hoof. Note that the outside wall has more slope, but it is totally straight. This factor can be frequently observed on hind feet.


Fig. 53




Fig. 54 shows another shape of a healthy hind hoof, although the camera angle does not allow one to judge the coronary band.


Fig. 54



Fig. 55 shows a beautiful set of front feet, the feet are of ample size, short in height, the RF (left in the photo) is well centered beneath the leg, the other one seems a bit off center, but it could be the angle of the camera. But note that these feet as well are a bit different.

The LF (in the picture on the right) has slight flares in the quarter walls, the RF is totally straight. Flares like this in my view are of no concern, but if at all in doubt, the tightness of the white line, or lack thereof, will be the deciding factor.


Fig. 55



Fig. 56 shows another set of ample sized front feet. But both feet are not centered beneath the legs and both are turning out slightly. Situations like these can easily account for the apparent flares and most likely the best diet and best trimming will never change that. This particular horse is totally sound on all terrain, and his feet serve him just fine.


Fig. 56




Fig. 57 shows a very upright, but very healthy hind foot. Again, there is some slight flare in the sidewalls.



Fig. 57




Fig. 58 shows the upright and very healthy front- and hind hoof of a horse that lives in very arid terrain. Note again some flaring. Also note the horizontal and straight coronary bands.


Fig. 58



In the next several images I will discuss flares that are of concern. Some hoof professionals consider all flares as a sign of weakness and will keep trying to eliminate them. From my own observation, flares like those shown in the hooves above are of no concern, and are most likely caused by uneven loading of the hoof capsule due to conformation of the leg, or an increase of wall density as the hoof capsule grows downward.

However, some flares indicate a serious problem in the suspension of the coffin bone, and most of those can be improved by diet, better trimming and maybe body work on the horse’s body.

Some will have to be accepted as an inherent weakness of a given hoof.


Fig. 59 shows a front hoof of a draft cross, with a straight outside wall, but a significantly flared inside wall. At age 2, this horse was flared all around the hoof capsule. This particular horse has very weak walls for his size, and any kind of diet improvement could not relieve this problem. Additionally, the hoof is not centered correctly beneath the leg, thus putting excess strain on the medial wall.

The horse is sound, but requires constant attention to hoof balance to minimize the problem. Note also the wall crack, caused by this strain.


Fig. 59



Fig. 60 shows a very unhealthy hoof, with unhealthy wall and significant flaring all around. This hoof has a serious problem with the suspension, the horse is very sore on hard ground, and needs a diet adjustment to grow better wall and coffin bone connection.


Fig. 60




Fig. 61 shows another hoof with a similar problem to that of Fig. 60, except that this toe wall is also much too tall, indicating either too much distal descent or a totally overgrown hoof wall. Only a close look at the sole could give this information.


Fig. 61



Fig. 62 shows an interesting scenario. The flare on the side wall would not concern me, but there also seems to be flare in the toe wall, and the coronary band is not straight.

It dips down some in the center which is usually caused by a poorly suspended coffin bone, which would go along with the toe flare. Also the sidewall on the right in the photo seems jammed up higher than the left one.


Fig. 62




Fig. 63 shows very overgrown hooves. The toe wall is therefore much too long/tall and has a severe flare. From this angle, the sidewalls appear quite straight until they get close to the ground.


Fig. 63



Fig. 64 shows hooves with multiple problems. Although not well visible from this angle, the toe wall is flared, so are all but one side wall, the coronary bands are very crooked, and the horn is of poor quality. The feet are too tall and the horse is toeing in with both legs, which causes the imbalances in the hoof. But the imbalanced hooves in return worsen the conformation issue. This horse would need to remain barefoot so it can be trimmed often to minimize the problem.


Fig. 64



Fig. 65 shows hooves recovering from founder. Note the big dip in the center of the coronary bands, indicating that the coffin bone still lacks proper suspension in the toe area.

If not rasped back that severely (which was the right thing to do) those toes would have had a very severe flare.


Fig. 65





The Shape when viewed from the sole:       Shape


In my previous discussion about the health of the sole horn, I purposely did not discuss the actual shape of the hoof from this view as the sole can be totally healthy as far as the horn goes, but maybe of less than desirable shape overall.


One of the most important criteria when judging hoof health from the solar view is the front to back balance of the hoof. The toe area of the hoof can easily be stretched forward too much, thus delaying breakover and resulting in toe first landings. The good thing is that the live frog will never migrate forward, and when we know where the tip of the frog ends (not necessarily the frog padding, but the live frog itself) we always have a reliable landmark. The frog and the coffin bone never change relationship with each other within the hoof capsule, no matter how distorted the toe wall may be. Since we know that part of the toe wall grows from the coffin bone, we can quite accurately determine where the toe wall should be. Different people have deduced different ways of measuring this. I like Gene Ovnicek’s way a lot. It is easy to follow. He arrived at his theory after observing and measuring many, many wild horse hooves. You can also read about Duckett’s dot, which generates basically the same measurements. Here is a link http://www.fairhillforge.com/Russellarticle.html . To learn more about Gene, you can visit his website www.hopeforsoundness.com .

Fig. 66 shows Gene Ovnicek’s way of assessing the bottom of the hoof. He also refers to the front contact points as ‘pillars’. This has become quite a widely used term for these points.


Fig. 66



Fig. 67 demonstrates one example of how Gene generated his measurement. The hoof in this figure is a cadaver front hoof of a mustang. One can easily imagine Gene’s drawing superimposed on this hoof. The striped area on the inside of the toe wall in Gene’s drawing is referred to as the toe callous. All horses have it, unless it is trimmed away, which one should NEVER do, unless the hoof is overgrown. In this mustang hoof, it is the tan looking area right inside the white line. The mule pictures further on in Fig. 76 show this callous very clearly.


Fig. 67





Cheryl Henderson came up with her own method. She uses an air craft clamp to superimpose a circle on the solar surface when assessing the hoof before trimming. For more information on this you can go to her website www.abchoofcare.com and you can join her yahoo discussion group which has great files and photos, and great discussions.

UPDATE
While I still think that this method can be a good guideline, esp. for beginners, following Cherylís method has caused many problems over the last few years, esp. her theory about heel height. Many people have trimmed hooves too severely and many horses have been sored to the extreme, even by Cheryl, as many people testified after attending her clinics. This is not hearsay, I talked to a good number of people personally. While I still feel that Cheryl has contributed lots of good things to barefoot in the past and most likely does so at the present, and undoubtedly has helped many horses, I no longer can recommend her trimming method with good conscious. Hopefully, Cheryl will implement some modifications that will allow her trim style to be of pure benefit for the horses.


Fig. 68 gives an explanation of her method. Incidentally, the hoof shown in Cheryl’s collage is the exact same one I used in the previous figure.


Fig. 68




The one thing I still need to add is that hind hooves are measured the same way, but because they have a steeper toe angle, the distance between the toe wall and frog is a bit less. You will be able to observe this distance on the sole images to come.


Now back to the overall sole shape.


I mentioned already that truly healthy front feet have less concavity than the hind feet. Additionally, they also have a rounder shape than the hind feet, the frogs are usually not as wide and the distance between the frog and the toe wall is a bit longer.


Fig. 69 shows three sets of one front and one hind foot each from 3 different horses. These feet largely fulfill the above mentioned criteria. Fronts are rounder, have less concavity, the frogs are not as wide in the heel area and the first 2 horses have a longer distance from frog to toe wall. The second horse’s hooves also show the toe callous very clearly right behind the white line. It is visible in all of the pictured hooves, but with variable clarity.






Of course, the shape of the foot again depends on the shape of the coffin bone. Naturally, a wide open and very triangular coffin bone will create a very different sole shape than a more oval one, esp. when the palmar processes are pointing towards each other rather than diverging. The latter condition would definitely cause contraction of the heels, and there are many different stages. A very severe stage is shown in Fig. 42.


The hooves shown in Fig. 69 all are wide open in the back, so a radiograph would reveal very triangular shaped coffin bones.


Fig. 70 shows the right front and right hind of a horse that lives and works on very rocky and dry terrain. Those are extremely healthy and rugged looking feet.

These are the sole shots of the horse in Fig. 58, except that these are the right hooves, and in Fig. 58 the left hooves are shown. This horse has genetically much more upright feet than the horses in Fig. 69, and therefore the sole shape is less round. These hooves do not show much concavity as they are filled in to some degree with dead material. This fact can be determined by the apparent “crack” or “dirtline” around the frog, a continuation of the collateral grooves.

As already discussed under sole horn, this crevice indicates buildup of dead sole material as the junction of live sole with the frog occurs at the very bottom of the frog. If one wants to know how much dead sole is built up, one would need to trim a bit around the tip of the frog until one gets down to the junction of sole and frog. While dead sole is not necessarily a good thing, I do believe that horses who work on terrain like this need it for protection, and I would not trim it out.


Fig. 70



Fig. 71 shows a horse from Spain with lots of dead sole buildup, and then with much of this dead sole removed. I see no reason why this sole should have been taken out, given the ground temperatures the horse has to endure, and its total soundness over all terrain as reported by the owner. There is still much we don’t know and understand about soles. I would however investigate the central sulcus of the frog. The heels do look contracted, and the central sulcus might be infected. Note also the black material in the white line near the heel/bar junction, which could also be due to disease and often goes hand in hand with thrush in the frog. Compare this to the health of the central sulci in Fig. 70. Both horses live in similar terrain. One major difference however is that the horse in Fig. 70 receives much more exercise. This could account for the much better heel width- and strength of those hooves.

Note that on both horses, Fig. 70 and 71, the outside walls are a bit rounder, the inside ones straighter. This is a very frequent occurrence and nothing to be concerned about. From the front, the inside walls would appear a bit more vertical than the outside walls.


Fig. 71



Fig. 72 shows another dry terrain hoof, very oval in shape, with impacted soles. What concerns me on this sole is that there is no apparent “crack” between frog and sole, and the frog padding has migrated forward too much. To find out about the health of this foot, I have to consult different angles.


Fig. 72



Fig. 72 a shows the hoof from Fig. 72 from different view points. The central frog sulcus seems fine, but the other views do reveal quite a problem: a pronounced toe flare. This would explain the strange shape of the sole. I would definitely take an x-ray of this hoof to help understand what is going on inside.


Fig. 72 a





Fig. 73 shows hooves, a right front and a right hind of the horse from Figs. 47 and 51, that are also genetically steeper and narrower and some people might call those moderately contracted. But this horse never wore shoes, always had good hoof care and is perfectly sound on all terrain. Note that there is not nearly the difference between front and hind hooves as seen in Fig. 69 and 70. Compared to the horses in Fig. 70 and 71, these feet look much weaker and much less rugged. Part of it has to do with the fact that these frogs are just recovering from thrush and have not returned to total health and strength yet, but part of it has to do with the fact that this horse lives on soft and wet terrain most of the year, not giving him a chance to build horn as seen in Fig. 70 and 71. These hooves resemble much more the horses shown in Fig. 69, who are also from a wet climate.


Fig. 73



Fig. 74 shows hooves with severe heel contraction that have just come out of shoes. The horse on the left lives in a very dry environment, the one on the right in a wetter one. Both horses have forward stretched toes and poor looking horn quality. This condition will take at least 1 year to resolve, maybe longer, but both horses most likely will end up with functional hooves. Once the long toes have been addressed, the pressure on the heel area will gradually diminish and the heels will be able to open up. But sometimes the damage to the inside structures may have been too much, and feet like these may never return to total soundness.


Fig. 74



Fig. 75 shows the sole view of the hoof in Fig. 60. Where a healthy sole would have concavity, this sole is actually bulging, indicating that the coffin bone is pressing down onto the sole, making the horse very sore. The tip of the frog corium is also pushed outward by this and it has practically no padding to protect the live frog plane. The frog itself is very diseased. Note the severe toe flare.




Fig. 76 shows one front- and hind hoof each of two mules. Like with the horses, the fronts are rounder, but they do have more concavity than a horse hoof, the heels do not reach as far back, the distance of the frogs to the toe wall is greater, and they have much stronger, unpigmented walls. Unfortunately, the frogs are in poor condition. Otherwise the hooves appear very healthy and strong. Note the prominent toe callous on all 4 hooves.





From the solar view, we can also judge appropriate heel height. One basic factor is that heels should end at the widest part of the frog, directly opposite of each other. If one heel ends a bit further forward than the other, chances are that it is higher. Sometimes, however, it can be due to a conformation problem of the hoof itself, but it is extremely rare.

Heels also should be a tad higher than live sole plane, between 2 and 4 mm. Some hooves may require making them level with sole, but generally in normal healthy hooves, there should be some heel visible beyond sole level. Personally I find that hind hooves usually do better with a bit more heel than front hooves. As hind hooves have to deal more with traction than front hooves, I find that a little bit more heel is helpful, esp. in soft terrain, and also seems to balance the hooves better front to back. Ideally the heels should form a little plateau, also called heel purchase.

Fig. 77 shows this principle. The green line marks the ends of the heels at the widest part of the frog, the blue circles indicate the “heel purchase”, and the heels are just a bit taller than live sole plane. The same principle can be observed on all healthy feet shown above. Sometimes it may not be as clearly visible, depending on camera angle or the height of the frog. If the frog is not fully developed and at heel height, it can look as though the heels end too far forward. And of course the heels of mule and donkey feet always end further forward than the widest part of the frog.


Fig. 77




Another important factor to look for when assessing the solar plane of the hoof is the shape of the wall from heels to pillars. There should be a moderate scooping of the wall visible. This scoop is naturally worn by horses who get plenty of movement, esp. on abrasive ground, and is created by the downward flexion of the hoof capsule in this area when the hoof is heavily loaded during impact. You may remember the discussion on the positioning of the coffin bone from front to back. This is where the back part of the coffin bone gets pushed down to ground parallel when loaded, assuming it has a certain elevation at rest and during low impact movement. Horses on soft terrain may not wear this noticeably as the ground gives too much and is not abrasive enough.

Fig. 78 shows a cadaver mustang hoof where this scooping is quite pronounced.


Fig. 78



Fig. 79 shows a domestic hoof with moderate scooping. This horse lives and works on soft ground. But when trimming, one should always make sure to shape the hoof wall like this. Some people say it should be enough that one can slide a credit card beneath the scoop.


Fig. 79



Last, but not least, one can observe the depth of the collateral grooves in the heel area.

Measurements have been established for this area, but like everything else concerning hooves, nothing is written in stone. Pete Ramey came up with a depth of ¾” in the heel area and ½” in the tip of the frog area, measured with a ruler or similar object placed across the hoof, and then measuring the vertical depth with another ruler. The front measurement is basically the depth of the concavity. I don’t know if he came up with any for the hind feet, but if so, the apex of the frog measurement should be around ¾”. I would regard these measurements as a comparative baseline, but certainly would not trim accordingly. Too many other factors need to be considered.

Again, hooves vary widely and they change throughout the seasons. For example, my own horses go through an entire hoof metamorphosis twice a year. In the summer months, when the ground is very hard, and they spend a lot of time in the barn on rubber mats because of the bugs, their hooves become very flat looking, with a much shallower collateral groove depth, and concavity practically disappears, such that I still get alarmed at times. The entire hoof capsule becomes shorter, and the frogs have practically no height at the apex, while on the winter hooves, frogs can measure close to one inch in height in this area. As soon as they spend more time again in the fields and the ground gets softer, they start rebuilding concavity, with concavity peaking at the end of the winter due to constant snow and ice pack. After the snow leaves, concavity diminishes again and again almost disappears come summer.

Wide open feet naturally have less collateral groove depth than narrow, tall and upright feet. So one horse can have less depth on his shallower and wider hoof and more depth on his narrower and more upright hoof.

That said, an extreme lack of depth can indicate a severe problem like a very badly damaged hoof capsule due to lack of proper suspension of the coffin bone, or extreme overtrimming of the heel area, or a totally crushed heel area due to excessive toes, while excessive depth can indicate severe contraction or much too tall heels.

Fig. 80 shows both examples. On the left a hoof with very shallow collateral grooves, heels overtrimmed, and on the right a hoof with deep caverns. This hoof needs considerable trimming of bars and sole, and most likely heels as well. Neither picture is of good quality, but I hope they help you to visualize the concept.


Fig. 80





The view of and from the heel area:       Top     Shape


The heel area should be judged in 2 ways: first with hoof on the ground and second with it held in the hand as shown in Fig. 79.


Fig. 81 shows a view of a horse’s front legs from behind. A view like this can give excellent information regarding stance and equal loading. We can see that this horse toes in, that his hooves do not squarely support the legs above, and that this problem is more exaggerated on the right. He obviously loads the outside of his hooves more and we may find unequal heel height for this reason. It may just be the angle of the camera, but the heels also look a bit too low, placing the hairline too close to the ground and possibly making the coffin bone ground parallel.


Fig. 81



Fig. 82 shows a view where one can see almost all 4 hooves. These hooves look very balanced and correct to me. The heels in the front appear a bit higher than behind, but again, I believe that the camera angle is to blame.


Fig. 82



Fig. 83 shows a close up of a very healthy back part of a hind hoof. I would like to see the frog/heel bulbs contacting the ground just a bit more.


Fig. 83




Fig. 84 shows the hind feet of a mule. Note how the bulbs are contacting the ground and that the heels are much further forward than in a horse.


Fig. 84




Fig. 85 shows a view of and from the heel area. Such a view can tell us lots of things. This is an extremely robust and healthy hoof, but note that the right side (in the picture) of the coronary band is closer to the heels than the left side. This means that this horse loads his left heel (in the picture) more and it pushes up the coronary band into what is called a sheared heel. As this horse is barefoot and seems to get a lot of movement judging by the robust condition of the hoof, the problem must be from conformation of the leg structure and most likely cannot be changed. From this view, one can also see the exemplary health of the frog’s central sulcus, the position of the bars (which I would lower just a bit), the “scoop” of the wall from the heel toward the toe, and the amount of concavity. The heels on this hoof appear quite high, but without seeing the rest of the hoof this is difficult to decide. Lots of factors play into heel height. I do NOT support the theory that all heels should be at a certain measured height. Personally, I feel that heel height is a consequence of sole thickness, overall shape of the hoof, the terrain the horse lives/works on, conformation of the leg/hoof, previous deformation of the hoof capsule etc. I highly recommend reading Pete Ramey’s articles on this subject.

Fig. 85



Fig. 86 shows a very contracted hoof as indicated by the closeness of the heels to each other and the tight central sulcus of the frog. Also note that the walls at ground level are closer together than at the coronary band, confirming the severity of the contraction. These heels are definitely too high. But the horse may have a genetic “club foot” and very upright legs, and this may very well be the limit for lowering the heels.


Fig. 86




Fig. 87 a and 87 b show the same hoof from a slightly different angle. Every little angle change can reveal different information. Fig. 87 a reveals that this horse seems to have a disease problem in the central sulcus of the hoof, the bars seem to overlay sole and there is a lump in the sole of the bar/wall triangle on the left. Equal heel height is not easy to tell from this picture. The walls scoop nicely from heel to toe. While the frog is well centered toward the toe, the right (in the picture) side of the hoof is wider and rounder.



Fig. 87 b confirms some of the impressions gained in Fig. 87 a, but gives better information about heel height. It appears now that the heel on the left in the picture is a bit longer. One can also see how the bars bulge over the sole in a ridge and the suspected disease of the central sulcus does not seem to reach as high into the hairline from this angle. I would think that this is the left front of the horse and that this horse is loading the outside heel more. The frog should have a bit more height between the heels to help distribute impact. The lack of frog height also indicates that there might be disease in the central sulcus. It also appears to be contracted, esp. if comparing it to Fig. 85.


Fig. 87 b



Fig. 88 shows a hoof with a diseased frog where the disease has penetrated far into the hair line. Once the disease is healed, this hoof will open up in the central sulcus and spread the heels further apart. Also note how this frog is not centered in the foot. It points to the left (in the picture). The bar on the right is impinging on the collateral groove and pushes the frog off center. The bar material needs to be removed from the sole along the entire length of the frog to allow the frog corium to return to its normal position. The sole has a peculiar shape in front of the frog and the toe wall appears to have been trimmed out of ground contact, both indicating that there may a problem with suspension.


Fig. 88




Fig. 89 shows an extremely contracted hoof, worse than the one in Fig. 86. Although the central sulcus does look a bit more open than the one in Fig. 86, the entire frog is very diseased and practically non-existent, allowing this extreme contraction. Note also in this hoof that the width of the hoof at sole level is less than at the coronary band. These heels are also too long, but the same reservation exists as for Fig. 86 with respect to lowering the heels to an ‘ideal’ length.


Fig. 89




Fig. 90 shows a hoof where the heels have been severely over-trimmed (in order to conform to a certain measurement). This leaves all the pressure on the frog which is extremely painful to the horse. If one would trim the frog to match the heels, one would most likely trim right into the frog corium.


Fig. 90



Fig. 91 shows an interesting shape. Note how the walls actually arc inward instead of diverging away from the coronary band toward a small hoof print, again indicating contraction. The frog seems robust and healthy and its horn seems to be free of disease even though the central sulcus is filled in. This strong frog helps to keep the heels apart, but note how contracted they still are. They are what is referred to as ‘inside the vertical’. Figs. 86 and 89 have the same problem, but not so pronounced. Also note the totally flat wall surface without any scooping from heel to toe. (This is the same hoof that is discussed in Fig. 72)


Fig. 91



Fig. 92 shows a hoof with a wide open central sulcus, but note the lumpy sole which really is not sole at all but bars laid over sole. They are actually higher than the sole and wall and must cause this horse great discomfort. The heels appear a bit tall and after cleaning out all the excess bar one might be able to reduce their height.


Fig. 92




Here is one more healthy hoof to conclude this article with. Fig. 93 shows a strong and healthy structure of a hind foot. The frog appears totally healthy, heels are at perfect height and end at the widest part of the frog, bars slope toward the frog, there is a definite scoop in the quarter walls and the sole shows excellent concavity.


Fig. 93





Below are a number of links that came up when I put “Healthy Hooves” into the search engine. You may find it very interesting to check out how other experienced students of the hoof define hoof health. No one has all the answers, and it is human nature to see things with very different eyes. We can learn from everybody and always have to keep an open mind. With enough data, we eventually will all arrive at our very own truth.



http://www.thehorseshoof.com/helphealth.html


http://www.behindthebitblog.com/2008/09/healthy-horse-hoof-experts-say.html


http://healthyhooves.ca/what-do-healthy-hooves-look-like


http://www.cvm.ncsu.edu/vth/ehc-sp/ehic/docs/healthy_feet.pdf


http://www.thehorse.com/ViewArticle.aspx?ID=7630


http://www.soulfulequine.com/blog/natural-hoof-care-healthy-hoof-six-ways-to-read-horses-hooves.html