Hoof form and function

When considering hoof form and function it is vital to look at the whole horse.  If a horse rider, trainer, professional is not already well acquainted with the principles of good conformation, they should become so or they should forget about horses and take up golf. Excellent conformation does not in itself lead to great athletic ability, and some great athletes do not have perfect conformation, but there are some non-negotiables. A key one is the ability to engage the fore and hind limb stay apparatus both of which depend on a certain set of hoof parameters - which centre around balance and comfort.

The equine hoof is far more than just a lump of horn around the foot bones (its metabolic activity according to Dr Strasser is equivalent to that of the kidneys); the horse spends most of its life with all four of its hooves in direct contact with the ground, and it has to combine all the postural and locomotor functions of a multi-toed foot in its single hoof.

Because the horse rests mostly upright, its overall health and well being is utterly dependent on the balance of its limbs. If a horse cannot load its coffin joints correctly, the suspensory apparatus of both coffin and the fetlock joints are under strain and the optimal balance between flexor and extensor muscle systems cannot be maintained. In that situation, the horse cannot properly engage its thoracic limb stay apparatus and has to tense muscles to remain upright, which leads to muscle tiredness and strain, and ultimately to the changing of its elbow and / or shoulder angle. This affects the way the all-important nuchal ligament functions in enabling the huge locomotor muscles of the back to relax. If the horse tries to alleviate hoof pain and /or muscle tension in the front limbs by standing under with its hinds, the hind limb stay apparatus will also be affected.

Relatively few horses have technically perfect hoof or body 'conformation' but they survive and may even thrive without it.  But, humans place demands on the horse that may take elements of the horse's conformation to breaking point. For a variety of reasons, the hoof is one of the horse's weak links.

In a very real sense, the horse with compromised hooves is not a truly healthy horse; the greater the degree of compromise, the longer it has been in situ, the greater the implications are for the animal's health.

Homeostasis

The ideal for any organism is homeostasis and for the horse, that relies on the maintenance of an essential balance in how the hoof is attached to the body, which affects how the joints are loaded and how the muscle systems operate, which affects how the hoof contacts and leaves the ground. Postural misalignments may result from hoof issues or they may create hoof issues, ie an imbalance in the hoof will result in imbalances in the rest of the body, which will perpetuate the imbalance in the hoof. 

Whatever the origins of a given problem, it can quickly create other problems and form into a series of overlapping vicious circles.  The longer that has been is situ, the harder it is for the horse to break out of it on its own. 

The best situation for the horse is to work its own feet and body back into an optimal balance but there are many occasions when that is simply not possible and the horse needs a helping hand - or two.

The Ideal 

Most horses will not have perfectly matched pairs of feet because the way their feet develop in their formative years will be conditioned by the amount and type of movement, their posture, the terrain they live on, and what they are fed.

BUT, the ideal is that each pair of hooves should be the same in terms of dorsal angle, concavity and size.

The front hooves are typically rounder than the hinds; the horse carries upwards of 60% of its body weight on its front limbs which the round shape of the hoof and the straight limb from fetlock to elbow reflects.

The hind hooves are more elliptical in shape and more concave which makes them better suited for propulsion, a factor that is also reflected in the way the hind limb is structured.

Just as the pairs of hooves ideally are the same in terms of size and shape, the two sides of a given hoof should be the same in terms of their basic parameters. This is especially important for the front hooves, but the closer all hooves are to an balanced shape, the healthier and more efficient they are likely to be.

Growth

Leaving aside the issue of diet, the growth of hoof horn is affected by circulation, abrasion and pressure. A more loaded area will abrade more and, depending on a number of factors, may grow in more steeply (which to a degree gives more efficient load bearing), or may compress or collapse. A less loaded area will grow more rapidly due to less abrasion and pressure and may either become pushed upwards by ground pressure or flare outwards, or break off.

A more divergent area of horn will be longer (in linear terms) than a steeper area and the ground most surface will contact the ground at a different angle. This affects the way the hoof responds to load. The greater the difference in terms of angles to the ground, the greater the potential for hoof and related musculo-skeletal issues.

Some people argue that a lateral or medial flare comes into being because the horse needs it and it is desirable for that horse at that point in time.  The hoof has to combine all the functions of a multi toed foot in a single digit, and that includes the lateral support which toes provide, but too much flare becomes pathological and affects the way the horse loads the hoof - and, depending on where the flare is, may affect the limb in flight as the horse tries to avoid striking itself.

Limb Alignment 

Hoof form will influence and be influenced by limb alignment, ie any deviation in limb alignment will be reflected in the hoof, which will in turn affect limb alignment and limb flight. Some deviations may be unchangeable, some may be offset only to a degree but a lot are correctable if caught early enough or given enough time and the correct management.

The greater the misalignment and the longer it has been in situ, the greater the implications for the horse's utility. Note I do not say the horse's survival; the horse can survive with grossly deformed feet but it will not thrive, its utility will be severely compromised and its longevity will be reduced.

The principles of optimal limb alignment are well established. Different sets of muscles, via their tendons, act across joints. One muscle - the agonist - contracts and its antagonist, 'plays out'. Ligaments hold the joint together, cartilage allows the bones to glide across each other etc etc. Each joint has an optimal range of movement, too little or too much causes problems. The muscles that act across a joint need to be in balance to ensure the optimal range of movement. Muscles, such as the digital flexors, cannot maintain optimal strength if they are constantly compensating for hoof imbalances.

Dorsal Angles

In a healthy hoof, the pedal bone sits high in the hoof capsule, with the extensor or pyramidal process (the point where the common extensor tendon attaches) sitting level with or fractionally below the coronet. The angle of the growth of the hoof wall and the angle of the pedal bone should be the same at all points around the hoof.

Although there is a range of dorsal angles (DA) in the pedal bones of horses, all horses will have some degree of difference between the DAs of their fore and hind pedal bones.  Typically, the front pedal bone has a DA of between 45 and 50 degrees, and the hinds 50 to 60 degrees. These DAs are derived from the pedal bone if it was sitting ground parallel.

Many horses end up with a more elevated or positive palmar (front hoof) angle than their plantar (hind hoof) angle. Assuming a tight laminar bond, a hoof with a 45 degree front pedal bone that sits at at 5 degrees above ground parallel will have an hoof dorsal angle (HDA) of 50 degrees. If its hind pedal bone has a 50 degree DA but it sits ground parallel, the hind HDA will be the same as the front.

Given the different primary roles of front and hind feet, this arrangement seems counter-intuitive. Yet, not only is this common, it is disturbingly common for the hinds to be shallower in angle than the fronts. 

Hoof-Pastern Angle

There is a long-standing debate about what the ideal or optimal hoof-pastern angle (HPA) is but everyone agrees that the HPA must not be broken - either forward or back. As Dr Strasser puts it, it must be harmonic, in other words, a line from the ground up the front of the hoof and pastern should be unbroken AND that line must intersect with a cannon bone that is aligned vertically to the ground.

Strasser  argues that the foundation for the HPA is a ground parallel coffin bone and that, given the way the hoof accepts full load, and the importance of a correct limb alignment to the all-important stay apparatus, it is illogical for the load-bearing front limbs in particular to have a positive palmar angle.

But many others point to a common finding from cadaver feet and radiographs of live horses that the front feet typically have a steeper hoof dorsal angle than would be the case if P3 was ground parallel. It is argued that, as long as the HPA is not broken forward or broken back, this is not a problem for the horse. The argument is that the pedal bone has to sit at a slightly elevated angle at rest, in order for the back of the coffin joint not to be stressed when the hoof is fully loaded.

I agree that a slightly positive angle in the front hooves is more easily accommodated than a negative angle and this would certainly be the case where the rear part of the hoof is poorly developed, but we need to ask why so many horses end up with high degrees of positive hoof angles in the load bearing front hooves, and ground parallel or negatively angled hind hoof angles, and what are the long term consequences for this.

Positive Palmar / Plantar Angle

The positive palmar / plantar angle comes about when the heels of the hooves grow longer and /or  the toe growth reduces (more persistent pressure and/or abrasion) resulting in a steepened hoof form which, even if the HPA is still harmonic, alters the way the digit and limb function.

Its key impacts are on the laminar and solar coria in the hoof, especially in the toe region; the suspensory apparatus of the coffin and fetlock joints, the circulation of blood through the hoof, and the angles of the elbow and shoulder joints.

The greater the angle, the greater the long term consequences for the horse.

Negative Palmar / Plantar Angle

A too shallow angle occurs when the heels on the hooves do not grow sufficiently or have collapsed ie they are long but are under-run or compressed, which leaves the back of the hoof too low relative to the toe. The toe runs forward which pulls the whole hoof under and forward, creates a lever force on the laminar structure and importantly, makes an energy efficient break over impossible.

If the back of the hoof is weak (thin lateral cartilages, weak frog and digital cushion, shallow angle to heel horn or lack of heel growth etc), the back of the coffin joint may be stressed under full load,  or even at rest. When this occurs the horse tries to reduce load on the heel by various measures.

In Summary

• The angles of the hoof wall must not differ from the angles of the pedal bone.
• The dorsal angle of the hind hooves must not be shallower than that of the forefeet in the same horse.
• The ideal is for the horse to have matching pairs of hooves.
• Too great a difference between a pair of hooves, or between the two sides of the same hoof, always signals an underlying pathology (in the hoof and/or elsewhere in the body) which always has negative consequences for the horse.
• The horse can accommodate imbalances in the hoof and limb to a degree, but they will have wider consequences for the animal's health and athleticism. 
• The responsibility of the owner and any professional working with the horse is to understand this, to correct imbalances as far as possible (which means looking at the animal holistically), and devise a lifestyle and a work programme which is appropriate to that animal, at a given point in time. 

GP or not GP, that is the question...

This was posted a couple of years ago on EC Hoof in response to a question about ground parallel pedal bones.


I trim to allow the horse to stand, land and move as naturally as it is able to at any given point in time. 'Naturally' is mainly what looks right to me but that relates back to the standard of 'good' conformation and movement I was taught decades ago - and which I see no reason to discard. 

I prefer to do the least possible and let the horse sort itself out - where it can - although sometimes I might trim quite intensively. 

It depends. 

I do take into account a horse's age and physical condition - especially joint adaptation / arthritis. There's no point in lowering a heel if the horse really can't or won't weight it. But I try to identify the reasons why it can't/ won't weight correctly and, if they are resolvable, address them. If they are not resolvable then the trim must aim for maximum comfort but (hopefully) not at the expense of vital functions. 

It's sometimes a tight rope walk.

The critical thing is to break the vicious circle of chronic pain, skeletal imbalance, muscle tension etc as quickly and as naturally as possible. The time frame, methods involved will all vary depending on the situation obviously.

I often don't get xrays - for practical reasons (cost, distance to clincs etc) - unless I really need to see inside the hoof. I work mostly on what I can see, feel and logically deduce from the hoof and from the way the horse stands and moves. But, sometimes I won't trim without them. And sometimes I wish I hadn't bothered because of the points John (Stewart) makes about the importance of angle etc.  

The points I am making about the ground parallel pedal bone are about whether it is just a theoretical plane from which to measure degrees of deviation. 

What is the acceptable deviation - John's 5-ish degrees, Pete Ramey's 1-3ish degrees, some farriers' 5-10+ degrees - or Strasser's 0-ish degrees? 

Why is it, as John says he observes in the UK, that it's ok to trim to GP on hind feet, but trim to as much as 10 degrees above that on the main weightbearing limbs? 

What are the implications, to the skeleton, of fore and hind pedal bones that are sitting at differential angles to the ground? 

Is this something which differs according to terrain? 

We know that hard terrain /high movement horses tend to have pedal bones carried higher in a more concave hoof capsule than soft terrain horses - and have thicker but more abraded (rolled) toe walls which look steeper than the thinner 'sharper' edged walls typical of soft terrain horses. 

Estimates of pedal bone orientation in these hard terrain hooves tend to come from populations of feral horses - as I understand it from x-rays of cadaver hooves or recumbent sedated horses - as it is very hard to x-ray a feral horse whilst upright.

What difference does a completely unweighted capsule make to how P3 appears to sit in the capsule in an x-ray? Can an artificial load on a cadaver hoof replicate natural loading forces? 

Strasser says that the cadaver feet of US mustangs she's seen have highly abraded toes but GP pedal bones. Current studies of Australian brumbies show a wide variation in dorsal wall angles - all steeper than 45 degrees but I don't know how these were measured or if x-rays were done and if so - how. Other feral populations like the ones here in NZ have more typical soft terrain hoof form. I have no idea about their angles.

I do agree that some horses can cope very well with a pedal bone that is quite forward of ground parallel - and that any pain and degeneration from that situation may be less problematic than the reverse situation of a too low heel with the back of the coffin joint being persistently stressed. 

The points I made about how stable P3 SHOULD be in a healthy hoof that is attached to a healthy properly functioning body - are not to suggest that I have a magic formula for restoring feet and bodies to that state. No-one does - and some horses will never have optimal feet because the opportunity to develop them has been lost forever. Some may well need a bit of extra height at the heel, ie the deal for them is that the potential for harm of an elevated palmar angle is less than the potential for harm of a GP pedal bone which is at risk of becoming negatively inclined on impact or persistently.

Which is pretty much the argument for shoes - the harm they do is outweighed by the harm they prevent.

BUT that doesn't mean a 5-10+ palmar angle is or should be the norm for all horses - and, if it is the case that a horse has such a weak heel that it needs extra heel height to avoid over-stressing the coffin joint and tissues at the back of the foot, aren't we ethically obligated to ask whether we should be exposing such a horse to high impact work - with or without that elevation of the palmar processes?

If Dr Strasser's calculations on load on the coffin joint are correct - the steeper the front feet are, the greater the load on the front of P3 and the greater the potential for laminar strain, solar horn damage and damage to the distal edge of P3. And that's aside from the question of how much persistently elevated palmar/plantar processes affect circulation. 

More on the caudal hoof - and the digital cushion

Everything about the way the hoof and the limb is structured is about dissipating ground reaction forces, ensuring traction, optimizing circulation and conserving energy.

The evolutionary advantages of the tough but lightweight single hoof are offset by the facts that:

• it has to fulfil all the loading and balance functions of a multi toed foot; 
• there is no contractile muscle tissue below the knee to buffer the bones and to aid venous return; 
• the joints of the digit are at a considerable distance from the muscles which act across them. 

To understand why the hoof and its limb have to function in a certain way, we have to understand the suspensory apparatus of the lower limb and its role in the stay apparatus; to understand that we need to understand the anatomy of the whole limb, and to properly understand that, we need some understanding of the anatomy and physiology of the whole horse.

It has become a barefoot mantra that the 'horse lands heel first', and as a result, the health of the soft horn/soft tissue structures of the heel is paramount. I agree with that but the heel first landing is important not just because the back part of the hoof is more flexible, it is also important because of bone alignment at the point the heel comes into land, which is important because of blood flow and muscle health.

At rest, the cannon should be vertical to the ground, and the pastern bones and pedal bone are offset to the vertical axis of the limb, ie the fetlock joint  is held in permanent extension and is able to achieve hyperextension by its suspensory apparatus. 

The tendinous interosseous muscles or suspensory ligaments  are strong enough to passively hold the fetlock joint in permanent extension, but elastic enough to allow it to hyperextend under load. At rest, the joint should be about 25% extended; at full load, it can extend to 180 degrees and even beyond.

The SLs are backed up by the digital flexor tendons, both of which have a check ligament that come into play to protect the contractile tissue of the muscles of the deep and superficial flexors tendons.

The deep digital flexor tendon (DDFT) is massive and has a fan shaped insertion point in the back  of the pedal bone. It is so over-dimensionalised not because it is needed to flex the lightweight pedal bone, or even because of its distance from its muscle, but because of its role in backing up the suspensory apparatus of the fetlock joint.

The coffin joint, between P2 and 3, has its own suspensory apparatus which gives the joint a greater mobility than the pastern joint (P1 and 2) but much less than the fetlock joint. Like the fetlock joint, the coffin joint has a sesamoid bone (navicular) which extends the bearing surface of the joint.

Both joints have an optimal alignment at rest, deviations from which can create a myriad of problems.

The hoof comes into land as the limb is being retracted, at which point the coffin joint should be fully extended with the digital arterial pathways fully open.

As the hoof engages the ground:

• the heels expand laterally and deform vertically; 
• the suspensory apparatus of the fetlock allows it to descend; 
• the suspensory apparatus of the coffin joint allows the two pastern bones to also descend, as a unit, with the fetlock;
• as the pastern bones descend, the angle of the back of the coffin joint begins to close and the digital arteries are compressed between bone and DDFT until, at full pastern extension, the blood flow into the hoof is completely closed off;
• after body weight has passed over the limb, the coffin joint is flexed and the limb is lifted off the ground;
• as the limb is extended, arterial flow is resumed.

Maximum fetlock extension is reached as the horse’s body weight passes over the vertical axis of the limb at which point the hoof should be fully and evenly planted with load dispersed across its volar surface and as a consequence, the whole bearing surface of the coffin joint. The extensor branches of the SLs are fully tensioned to stablise the coffin joint.

The venous plexuses are expressed by the reversible deformation of the hoof capsule and the mechanical regulation of arterial flow when the heart is pumping hard is a vital part of balancing hydraulic pressure in the hoof. 

Problems occur when the persistent alignment of the coffin joint mimics the degree of pastern extension that occurs at high impact. This can happen with a grossly steepened pedal bone where the palmar/plantar processes are elevated, and in a ground parallel pedal bone where the hoof-pastern angle is severely broken forward.

The role of the Digital Cushion

As the pastern bones descend, the digital cushion (DC) is engaged. This is a structure that is both misnamed and misunderstood.

It is widely argued that the DC aids shock absorption and also contributes to venous return by helping to mechanically express the palmar venous plexus.

Strasser argues that the DC’s effectiveness, both as a shock-absorbing cushion, and in transmitting ground reaction forces to the lateral cartilages, is negated by its ability to displace caudally because there is only thin skin at the back of the pastern above the heel bulbs. Because of its location and its structure, she argues that it is more akin to a sling, the role of which is to assist in arresting the downward pressure of the pastern bones under load and with the bars, to assist in controlling the lateral expansion of the heels.

The DC is made up of horizontally arranged bands of fibrocartilage (FC) that  attach to the lateral cartilages and run above the frog corium and below the distal fibrous sheath of the deep digital flexor tendon (DDFT). There are tubular glands over the spine of the frog, ducts from which pass through the frog dermis to the frog surface. Strasser argues these are vital to frog health as they affect the pH of the pad and help make it resistant to pathogens.

In between the fibrocartilaginous bands is loose connective tissue (LCT).  The proportions of FC to LCT varies between hooves and Bowker argues that lots of fibrocartilage is evidence of a healthy hoof. He also argues that in a healthy hoof, the lateral cartilages are thicker and denser. it seems logical that this would be the case but there are many other factors at play.

Fibrocartilage is a specialist type of cartilage that contains Type 1 collagen as well as the normal Type 2 which is the main component of cartilage.  Type 1 is found in skin, tendon, vascular ligature, organs and is the main component of the organic part of bone.

The fibrous element in fibrocartilage confers flexibility and toughness, and the cartilaginous element confers elasticity.

The proportions of each element in any given digital cushion may vary according to such factors as age, breed and importantly, the terrain the horse lives on and how much movement it gets. The relative amounts of the two types of collagen may vary as well.

Cartilage has no blood vessels or nerves of its own. The cells that secrete the matrix of cartilage and become embedded in it obtain all their nourishment from blood vessels in the perichondrium (the connective tissue that envelops cartilage where it is not at a joint) and surrounding connective tissues – and it does so by diffusion of oxygen and nutrients through the matrix. It is because of this lack of a direct blood supply that cartilage heals so poorly and the lack of nerves is why a weak DC in itself will not cause discomfort.

With age, normal cartilage may calcify which inhibits the diffusion of nutrients through the matrix and may result in degeneration of the cartilage. I do not know if this happens to the cartilaginous components of the DC.

For diffusion to occur, cartilage (and tendon & ligament) need movement - preferably under load.The movement the DC gets is from the direct expansion and contraction of the heels, and to a lesser extent, from the upward pressure of the ground on the frog pad.

The horse evolved from a multi toed ancestor and it contains remnants of those toes in the splint bones, the ergots and the suspensory ligaments which, as their anatomical name indicates, are not true ligament. It is suggested that the SLs of certain breeds (eg standardbreds) contain a higher proportion of muscle fibres than other breeds; perhaps the same is true of the relative amounts of the different types of tissue and/or collagen in the digital cushion.

The truncated cone shape of the hoof, the attachment of the caudal (rear) part of the hoof to cartilage, the inward turning of the walls, and twin folds of the frog in its rearward third  - all enable the hoof to reversibly deform (expand) laterally under load, to compress, and for the heels to displace vertically.

The hoof has to have a balance between the load bearing properties of a vertical structure and the load spreading properties of a diverging one. 

Too vertical a cone concentrates ground reaction forces on a smaller area and is less capable of dissipating energy, ie it is more prone to concussive damage both of hoof and the structures it protects.

A too diverging cone will spread load over a wider area but be incapable of retaining vertical integrity and will expose the sole and pedal bone to the effects of both concussive and persistent loading.

In either extreme, the soft horn/soft tissue structures of the caudal hoof are permanently deformed, incapable of the desirable degree of reversible deformation that is the basis of healthy hoof mechanism.

In the narrow hoof form which cannot deform sufficiently under load, and especially if combined with a steepened bone alignment: 

• blood flow will be compromised; 
• the DC in particular will not get the movement it needs for diffusion to occur and atrophies; 
• the bars will deform and very likely become high pushed, compressing veins and arteries and causing discomfort; 
• the LCs will be deformed by the inward turning heels; 
• the laminar corium in the heels will be under a state of persistent pressure; 
• the frog corium will be starved of nutrients and the glands that maintain its protective acidic pH will not be able to function; 
• shock absorption will be reduced with consequent effects on the joints; 
• a steepened bone alignment will throw out the balance necessary for the optimal operation of the stay apparatus and may impair arterial flow to the frontal regions of the hoof in particular; 
• the abnormal angle of the pedal bone to the ground, combined with the mechanical effects of high heels or short toe, will force the horse onto its forehand, overloading the toe reducing toe growth, stressing the solar corium, allowing greater heel growth ......

In the splayed hoof form:

• vertical integrity cannot be maintained; 
• the heels may expand too much under load; 
• the DC will be unable to get the stimulation it needs for nutrition and, as a result, will atrophy; 
• the pastern bones have nothing to dampen their downward movement; 
• the frog will be exposed to too much direct pressure; 
• the back of the coffin joint will be exposed to too much movement overstressing the suspensory apparatus; 
• the same applies to the SA of the fetlock joint and as a result the SLs may be damaged;
• the horse may try to  steepen its pastern angle by contracting its flexor muscles and, because that cannot be maintained for any length of time, by changing its shoulder/elbow angles which will impact on the muscles of the upper limb, shoulder, neck and back; 
• the entire volar surface of the hoof will be exposed to too much concussive impact and persistent pressure and of course bone yields to persistent pressure ......

This is not an exhaustive list of the worst case scenarios but it gives a flavour of the sorts of things that can - and do - occur. 

Some horses have one hoof of each kind; some have steep high heeled hooves on their load bearing front limbs and shallow low heeled long toed hooves on their hinds. 

What we must all agree on is that every part of the hoof has a role, and all are important.  The role of some parts of the hoof and the ill effects of them not functioning optimally are immediate and obvious; that of other parts may be less obvious and more gradual and subtle. 

The bottom line is  :

• the hoof is a unit ;
• the whole hoof is more than a sum of its parts, and
• the whole hoof is never truly healthy if any of its parts is unhealthy, and
• the whole body is never truly healthy if the hooves are unhealthy.

The Natural Horse

Horses are a subject that most non-horsey people find very boring and horsey people find endlessly fascinating. One area that always results in the temperature in the equestrian world being raised to boiling point is the natural versus unnatural argument.

The moment we domesticate an animal we change its natural way of being. It is obvious, to all but the irredeemably stupid, that, if we change an animal's natural way of being too much we will cause it harm. There has to be a balance between what the animal needs to be healthy in body and mind and what we want it to do for us. 

I have heard people, who seek to legitimate highly unnatural ways of managing animals, argue along the lines that, as very few people can achieve the 'natural' ideal of running horses in a herd on 100 acres of wilderness, then keeping them isolated in a stable is ok. An equivalent would be to argue that, as if you cannot keep pregnant sows running in a forest, it's ok to keep them in crates. 

We subject the horse to extremes, we ask it to run further, faster, jump higher than it would ever choose to do in nature. The horse is not stupid, given the choice, it will conserve energy and avoid dangerous obstacles and it will stick to known pathways if possible. In so doing, it obeys the evolutionary imperatives of conserving energy and staying with its herd. 

We want to keep horses in stables or small paddocks because it is convenient to us. These conditions mean their feet cannot become or remain as tough and well conditioned as they need to be to cope with what we want them to do and are prone to being worn or contused. But we want them to jump massive tracks on potentially slippery or hard ground - at our convenience, and, for the safety of the rider and animal welfare considerations we don't want horses falling and breaking a leg or neck too often, so we shoe them to 'protect' the hoof from wear and bruising, and add studs to improve traction. We do this despite the fact that shoeing - even the very best shoeing - invariably causes some damage to the hoof. The logic behind shoeing is that any harm the shoe does is offset by the harm it prevents.

Why not breed for good feet, condition the feet from birth and keep the use of the horse within the limits imposed by its biology?  

We know that at liberty a horse adopts display posture only briefly and can alter its posture the moment it needs to. We know it needs an extended neck and a dryish, closed mouth to be able to breathe efficiently. In advanced dressage, under conditions at which the physical demands on the horse are pretty extreme, tradition insists on an 'outline' that inhibits respiration at a point when the degree of musculo-skeletal stress demands respiration be at its most efficient. And, it insists on the use of a certain type of equipment - a double bridle - to achieve and maintain that outline, which also reduces the efficiency of respiration. 

Show me the advanced dressage horse that competes with the dryish, fully closed mouth of the horse exercising at liberty and I'll show you a hundred that are slobbering wildly and have their mouths open. The simple fact that people think the slobbering is desirable demonstrates a lamentable lack of understanding of the competing physiological processes involved in eating and exercising.

It is insane. And it comes from an era when the prancing, 'prettily curvetting', horse was a status symbol of the rich and powerful. You have only to look at most statues of kings, princes and military leaders astride horses and invariably the horse's mouth is open, its jaw is twisted and its eyes are wild - a picture of a horse in pain, or in fear of being in pain. To the educated eye it is ugly. It's like the terrified grimace of a young chimpanzee that is presented to a gullible human audience as a 'smile'. 

We subject the horse to a grossly unnatural lifestyle. We may have selectively bred for size, performance, athletic ability etc but their fundamental species needs remain unaltered – as do our own. 

I make no apology for the following. It may sound emotional – it isn’t. I love horses but this is a fairly dispassionate list of what the horse's species needs are versus what we do it – to meet our needs, or what we are led to believe should be our needs.

What follows is not an exhaustive list although you may feel exhausted after reading it. 

The horse :

is a highly social and hierarchal herd animal -  it is often isolated and/or exposed to sudden changes in its herd environment;

is a prey animal whose defence is flight and which evolved to move 18 hours a day  – it is often confined to stables and small pens;

needs confidence in its ability to flee from danger and to stay upright –  the way it senses the ground and the way its feet cut into the ground are changed by shoeing it;

is a trickle feeder, grazing head -low 16+ hours a day – it is usually fed to human convenience and needs;  

needs high fibre and varied forage  - it is often fed on sugar rich, too easily available grass and legumes and grain based hard feeds that are often coated with sugar and treated with chemicals, and it is often denied high fibre food to prevent a 'grass belly';

controls its own worm burden by moving away from its droppings – it is often forced it to graze worm infested grass and then dosed with wormers, whether or not it needs them;

needs the pumping action of its feet to aid venous return – the normal expansion and contraction of its feet is often changed by the way we trim (or don’t trim), manage the lifestyle and by nailing or gluing on shoes;

needs to keep its spinal ligaments tensioned to allow locomotor muscles to function optimally, which requires head low posture – we often create a range of conditions in which it stands and moves head high and/or with a hollow back;

needs a balanced skeleton to maintain its stay apparatus – we often force skeletal imbalances on it with resultant soft tissue damage, by the way we balance its feet, shoeing, poor riding, discomfort from bits etc;

is more prone to over heating than cold and has an efficient thermo-regulation system - we often rug and clip it for our convenience and because we project our needs onto it;

needs properly aligned teeth for nipping and grinding – we often affect the wear of its teeth by what we feed it and how we keep it and we have its teeth balanced while it is in a head high posture which changes the alignment of the jaw;

has a highly sensitive mouth and muzzle - we often damage it through the use of bits, chains, straps, tie backs, tie downs etc;

requires a relatively dry, closed mouth, a fully closed gullet and full extension of its neck for ensure efficient respiration - we often force it into flexion which inhibits this, prevent it from fully closing its mouth by placing bits in it, stop it opening its mouth to evade the pain of the bit by strapping its mouth closed or tying its tongue down ......

And, in addition to all that - we often cut off its sensory whiskers, pull the hairs of its mane and tail out by the roots, wash the natural oils out of its coat, spray it with silicon based products to make its coat shine, expose it to toxins from artificial fertilizers, herbicides, pesticides and anthelmintics….

In short, we often create conditions in which the horse is exposed to psychological, digestive, muscular-skeletal, circulatory, metabolic stress - and all too often, when its system breaks down, we then subject it to a whole new load of stressors trying to cure it.

Having these sort of views about animal husbandry in general qualifies me to be called a’ tree-hugging, granola eating kook’ or a ‘rabid PETA whore’  by people with Over-Active Amygdala Syndrome (mostly, it has to be said, horse owning residents of the USA where the condition seems to have reached epidemic proportions).  

I don't expect everyone to do as I do, I just want to encourage people to stop and consider why they do what they do - not just do it because other people do it, or say to do it, or because it's easier, or because it's always been done that way. 

Getting a kick out of a horse

Some time ago there was a front page story in the Christchurch Press about injuries caused by horses  and the cost to the tax payer. The story was headlined  ‘Hellish toll of hooves’ but it failed to mention the main reason for the toll– ie the metal shoe that is so often nailed to the hoof.  

A horseshoe can best be compared to a knuckleduster on a human fist in that it adds weight and rigidity to a comparatively light and flexible structure.  In so doing, it hugely increases the ability of the hoof to inflict major cutting, crushing and cracking injuries to both soft tissue and bone.

More Accident Compensation Commission claims result from riding accidents, than for rugby.  Most involve riders falling from horses but the most expensive are those that require extensive and complex reconstructive surgery.  Being kicked or trampled in the face and head will almost always fall into that category.

A horse’s kick can transfer a force of more than 10 000 Newtons to the body. Medical trauma personnel have likened the destructive potential of an equine kick to that of the impact of a small automobile moving at around 30 kms per hour. A kick can shatter bones and severely traumatize soft tissue externally and internally. Medical journals document people going into cardiac arrest after sustaining a kick to the chest.

A Swiss study of traumas inflicted by horses concluded that the equestrian community may underestimate the risk of severe injuries attributable to hoof kicks, especially while handling the horse.

The horse has evolved a highly specialised foot bone for its single digit. The equine pedal bone and its protective covering of horn has very high tensile strength but is very light. This conserves energy which, for a prey animal whose main defence is flight, is an important consideration.

A metal shoe can more than double the weight of the hoof capsule.  This has major consequences for all the forces that act on the horse hoof and limb – ground reaction force in particular.

The horse without shoes not only has a lighter, flexible hoof at the end of its very powerful hind limbs, it has a better sense of the velocity and therefore the strength of its kick. 

The horse may strike out with its front legs but it is the hind limbs which deliver most force. The hind limbs are the horse's engine – the propulsion unit, and they are also a major defence mechanism.

http://www.youtube.com/watch?v=cCG7HWdRtkQ

The worst kick is from one or both back legs – delivered when the target is right behind the horse and at enough distance that the limbs can reach maximum velocity. Being ‘double barrelled’ by a horse has a special meaning for all horsefolk. You don’t want to have it happen to you and if it does, you want to the horse to be shoeless.

A horse than means to hurt you will do so if it connects. And they can be astonishingly fast and accurate.

http://www.youtube.com/watch?v=XqZ4UUDoZGs

Leaving aside the extreme provocation of having a red hot branding iron applied to its rump, a horse that kicks without warning means to do harm especially if they kick out at head height. Such a horse is either feeling very threatened and wants to get in first, or it is being aggressively dominant.

However, most horses do a lot of threatening before kicking. There’s almost always a lot of horse talk going on that many humans are not aware of, choose to ignore or worse, answer back in a manner that escalates the potential for conflict.

Horses which are kept in highly stressful situations, are in pain or anxious about pain, and / or are badly trained are far more likely to kick without warning. I have never been kicked by one of my own horses yet I quite often trim their feet sitting on a box with the hoof in my lap.  They are barefoot, live in a herd and are well trained and at peace with the world.

Aside from kicking, there are stamping, trampling type injuries – ranging from the very common standing on a toe through the slamming of a hoof onto a foot to being run over by a fast moving horse.  A race horse can gallop at around 50 kms an hour– and it can weigh upwards of 500 kilos. Its kick may feel like being hit by a small car at 30 kms an hour – being trampled must feel like being run over – and over – by a small car.

Dr Hiltrud Strasser, an outspoken advocate of keeping horses barefoot, suggests that, such are the dangers of shod horses, people riding or working with them should have to wear protective head gear. Given the numbers of major facial injuries inflicted by horse’s hooves, perhaps this should be full face helmets. We have laws which require cyclists (motorized and non motorised to wear helmets, why don’t we have a law requiring the same of people who are riding and handling horses which have the equivalent of knuckle dusters attached to their feet?

Just a thought ….