Easycare Down Under gets many emails from horse owners seeking help to select the best boot for their horse. Sometimes its necessary to understand a little of the processes that distort and deform domestic & performance horses’ hooves to understand the role of boots in the rehabilitation process.  

Mike Ware, Manager Easycare Down Under, an Equine Podiotherapist and a Director of the Australian College of Equine Podiotherapy (www.equinepodiotherapy.com.au)  offers the following insights. 

Please note the information featured here is offered as an "over-view" only of natural hoof care rehabilitation.  If you have any lameness or serious hoof issues these should be discussed with a veterinarian familiar with natural hoof care rehabilitation.

Sadly most of the issues our domestic and performance horses suffer stem from a condition called "hoof deformation" . It brings with it also many secondary upper body musculo-skeletal issues too.

So here is a cooks tour of the most common hoof issues that may be addressed with natural hoof care methods.

 

 

Long toes, under run heels, contracted heels, flares, hoof cracks, quarter cracks, thin soles, weak walls....................they are all caused by the process of Hoof Deformation!

What is hoof deformation?

It is a slow and gradual distortion and finally the collapse of the hoof capsule.  The distortion can vary from a minor imbalance to serious deformation where the hoof capsule looses its structural integrity and begins to squash and and compromise the internal soft tissues of the hoof.

The hoof is not a hard unyielding lump on the end of the leg. It's a living dynamic structure always reforming itself in response to the stresses put upon it. If they are incorrect stresses then the hoof reforms into an incorrect form.  With years of incorrect loading and stressing it will reform into a shape that is at war with the horse's own biomechanics.

Inappropriate stresses on the pedal bone (P3) eventually cause regional bone loss and as the pedal bone strives to balance an unbalanced hoof the palmar processes elongate begin to ossify (turn to bone) these can be seen on radiographs.

The further the hoof form verges away from physiologically correct the more obvious are the outward visible signs. The rate this condition advances depends on the type and quality of hoof care the horse has received during its life. Diet and ongoing sub clinical lamintis issues also play a huge role is speeding up this process.  

It can be usually reversed with correct hoof care and a suitable diet but it takes time.  Left unchecked it may continue to progress to the stage where the horse develops serious hoof issues.

 

How do you know if your horse has hoof deformation?

If your horse's hoof form displays the following characteristics then he most certainly has hoof deformation. These are not stand alone conditions as we formerly thought, they are the outward signs of hoof deformation and mirror the internal problems developing also. 

Some of the most common outward visible signs of hoof deformation shown on the photo below are:

            1.                   A raised upward swoop in the coronary band.

2.                   Overlong and under run heels (although they are very low you will see they are also very long)!

3.                   Cracks in the hoof wall. These appear because the horse's weight in motion flexes the unnatural hoof form constantly at that point so it weakens and cracks. Restore normal form and they grow out. Yes they do!!!!

4.                   Horizontal lines appear in the hoof wall from sub clinical laminitis episodes.  These are not "growth rings" as we used to think.  They are a warning sign of sub clinical laminitis.   

The white lines on the photo indicate what the physiologically correct hoof form should be for this horse.        

The photo below looks to be a neatly shod hoof but beware neatness has nothing to do with structural integrity!  Observe the indicators of hoof deformation:

 1.      The heels are slowly moving closer together with every shoeing as the horse's hoof from deteriorates.

 2.       The biomechanical fulcrum point of the hoof is so far forward that there is no support base at the back end of the hoof. The suspensory apparatus is now compromised when working at speed.

3.       Heel bulbs are hanging out behind the shoes like 2nd story verandahs! Huge leverage forces are now crushing the caudal hoof area (heel area).

4.       Horizontal lines are indicative of sub clinical laminitis episodes. In performance horses this can be due to mechanical laminitis from hard work on hooves suffering the stresses of hoof deformation.

5.       The pink line shows how out of shape the dorsal wall really is and to what a great degree this hoof is distorted.  The front of the hoof has been "bull nozed" off to cosmetically appear more attractive. It does not help the poor hoof form or deal with the collapse happening in the caudal heel area.

 

What does hoof deformation do to the inside structures of the hoof?

The internal hoof is chock full of wonderful evolutionary adaptations that make the horse the fast and agile animal it is today.  Provide it with access to varying terrain and the hoof is totally self sustaining. 

Hoof deformation has great impacts on these internal structures.

We all know that the hoof was once the middle toe of a tiny browsing animal and that when it left the forests to graze on the plains for a few million years it evolved to be larger and faster. To be larger and faster, required that it develop a hard hoof and it slowly lost the use of its outer toes and now stands on the nail of its middle toe! 

What most horse owners are not told is that the structures at the back of the hoof (the caudal heel area) took on the new and important role of dissipating the huge amounts of concussion that are caused with every stride. 

Wonderful and unique adaptations appeared in the soft tissues of the caudal hoof. They protect the animal from shock waves and concussion and although the hoof appears hard and unyielding without these structures the  shock waves from a 600 kilo animal hitting the ground at speed would shatter their legs. 

Because of the wonderful heel mechanism, concussion is arrested in the tissues at the back of the hoof by unique circulatory adaptations called haemodynamics and by a robust fibrous digital cushion. But this can only be done successfully when the caudal heel area is healthy! 

When hoof deformation occurs and the hoof capsule shape distorts the capsule its looses its integrity.  The digital cushion becomes fatty and soft and the hoof capsule deforms and folds down on itself at the heels.  In some cases the heels contract and move closer and closer together also squashing the internal structures. Either way the tissues in the caudal heel are very compromised. 

This area is rich in sensory nerves that detect pain and pressure, they allow the horse to feel the ground and damage there causes ongoing pain. Theses horses don't limp because it happens in both front feet at the same time.  But the horses do try to protect their sore heels by changing their strides and postures. They begin to move like "stick insects" and their bodies begin to stiffen from guarding sore hooves with every stride.

Inside the hoof as deformation continues the lateral cartilages, digital cushion and frog begin to suffer from the affects of atrophy. Soon these tissues are unable to perform their functions as shock absorbers and protectors of the bottom of P3 (the pedal bone) so the shock waves pass up the bony column and affect joints, ligaments and bone.

Professor Robert Bowker of the Equine Hoof Laboratory at Michigan State University in the US found in his research into the functions of the hoof at cellular level, that the hoof wall construction shows no signs of developing tissue that is meant to bear the total weight of the horse. Just tissue meant to bond the bone to the hoof capsule wall.

Weight bearing in the hoof is meant to be shared by parts of the sole, the inner walls, frogs and the heel platforms of the hoof. In advanced hoof deformation these structures are very dysfunctional. It's a testament to its amazing engineering that the hoof can still function somewhat when it is totally peripherally loaded by a shoe.   But in time this suspension of the wieght off the walls bring the laws of physics into play and the hoof capsule begins to distort. 

  

I have been told my horse just has bad feet!

No horse just "has" bad feet. 

Although different breeds have slightly differently shaped hooves the variance from normal is very slight indeed. Bad hooves are acquired from years of bad hoof form & incorrect diet.

For too many years we have used very subjective methods when balancing up the hoof.  Its not longer acceptable to just sight down the cannon bone and set up the hoof at 90 degrees.  Nor is it acceptable to just feed our horses diets designed for fattening cattle.  Horses require a totally different diet and a hoofcare regime based on a paradigm governed by the principles of orthopaedics so they will remain sound for life.

The principles that govern healthy hoof form have only tiny variations between breeds. The basic hoof that evolved has changed little in millions of years and a few thousand years of domestication is not enough time for any evolutionary changes to happen. The biomechanical parameters for healthy hooves are the same throughout all breeds when you use "living landmarks" as your guide. 

No horse breed has cracks and splits and under run heels naturally. These are "acquired" issues and in some equine disciplines they have become so common that we now actually blame the horse for his hoof problems! 

When a hoof is correctly balanced using biomechanical landmarks, hoof cracks, quarter cracks, under run heels and forward feet can usually be returned to normal.   Cracks are merely a sign that there is too much leverage from the hoof distortion being focused at that particular point. Remove the leverage and the crack will close and grow out. 

    

How do you spot hoof deformation issues just from the horse's gaits?

Researchers are only now discovering the huge amount of secondary postural and gait issues that stem from living constantly on hooves with caudal heel pain. Much of what has been thought of as arthritis pain can now be related to poor hoof form.

Many horses with hoof deformation carry vague and ongoing body problems that we call therapists to attend to. They limit their performance and cause time off from training but unless the source of the problem is also addressed, the hoof deformation, then  the problems just return again and again.  You only need to look down at their foundations to know why. 

Hoof deformation cannot be seen on exrays until it is very advanced and has caused serious changes to the bones of the hoof.  For years before that the horse will have lived with soft tissue caudal heel pain and secondary musculo-skeletal issues. 

 Beware! Toe first stride landings!

To get relief from those sore heels horses change their gaits and resting postures.

They will try to do toe first stride landings whenever they can as shown in this picture. Performance horses working at fast paces are unable to do toe first stride landings,  (their biomechanics over-ride their ability to do this) so if they have pre-existing heel pain it is aggravated by fast work.  

These adaptations can be seen by the naked eye if you watch the horse walk on flat ground. Often if they are walking on sandy tracks you can see a tiny spray of sand spurt out ahead of the hoof as the place the toe down.  These horses often stumble when they accidentally stab their toes into something solid on the ground surface.

Normal stride landings at the walk should be heel first. Toe first landings change the normal biomechanics of the distal limb and cause the tendons to bear weight in an abnormal way this causes cumulative trauma to the tendons.

Horses who stumble, trip, over reach and collapse at the knees usually have advanced hoof issues.

   

How can you spot horses that have body problems from sore hooves?

Even if you don't know a single thing about recognising deformed hooves you can still clearly see the obvious "postures of pain"  that come from years of living with caudal heel pain.

Because of the biomechanics of the equine the front hooves are usually the ones that suffer hoof deformation pain first. So the horses begin to adopt a leaning forwards stance to get some weight off those heels. 

There is no such conformation issue as "over at the knees" what you are seeing is the horse leaning forwards for relief. 

If your horse is standing like a circus elephant on a box as this one in the photo is, then he has caudal heel pain and hoof deformation issues and will also certainly have secondary musculo-skeletal issues.  This posture is indicative of "reversed angles" when the hoof form has verged so far from physiologically correct that the forefeet and hind feet angles are reversed.  This causes a lot of secondary issues in the hock and stifle and pain in the lumbo sacral area.

 

 

Can corrective shoes fix hoof deformation?

No its not possible to help restore a physiologically correct hoof form by corrective shoeing.  A large part of the hoof deformation process stems from the hoof being held off the ground by a rigid steel band, whilst peripherally loaded on the walls. Corrective shoes and wedge shoes will further crush the caudal heel area and speed up the deformation process. They are merely palliative care for horses not rehabilitation.

If you have a horse suffering navicular syndrome this is directly related to hoof deformation, you need to contact an Equine Podiotherapist who can discuss his rehabilitation with your veterinarian. There are new techniques available now that do not require invasive procedures.

 

Why are some horses so sore when their shoes are removed?

When you remove your horses shoes often the comment is made "look how sore he is ........... you can see he needs shoes". 

Actually what he needs is hoof protection and rehabilitation! You are only now seeing the full extent of his hoof damage.

When you see horses creep along gingerly guarding every step, its not because they "need" shoes its because their hooves have become so dysfunctional the protective soft tissue structures have wasted away and now they are walking on depleted soles, so they are very tender. 

If you are going to remove shoes from a long term shod horse then do not apply a barefoot trim straight away.

 

How to transition out of shoes.

Leave as much of the sole as you can for protection no matter how cruddy it looks. Then just turn the horse out in a soft pasture with a bland diet and do not touch his feet for a couple of weeks. There are many changes happening inside those newly unshod hooves and the horse needs time to adjust. Good trimming is often not about what you take off, its about knowing what to leave until the hoof can cope with trimming that encourages it to reshape into a more healthy form.

When you come to trim the horse you will probably see that there is a lot of flaring to remove on these imbalanced hooves. Be careful and only take off the flares on the bottom third of the wall. Never allow trimmers to file flares off all the way up to the coronet band it creates excess flexion in the hoof capsule and promotes soreness.

These hoof capsules are already weakened and if you make the foot look tidy by filing off flares up towards the coronary band you will have a very sore horse.  If you just remove the flares from the bottom of the hoof it still removes the leverage forces.  In a couple of trims you can deal with the rest of the flares as they grow down.

 

How do you reverse hoof deformation?

Firstly you need to redevelop those depleted caudal heel structures and slowly remove the leverage forces from bottom of the walls, plus get those heel platforms re-established...basically you are going to try to restore normal hoof balance so that the biomechanical centre of the hoof is again in the correct place, and the horse bears weight as it should. 

This cannot be done in one trim and if you try to do it that way you will make your horse very very sore. Never let anyone weaken the hoof by excavating bars they are part of the structural integrity of the hoof and this practice will not decontract the hoof.

Rehab. must be done slowly over many trims. There are years of damage in that hoof and it may take six months or longer to reverse it.  But......if your horse is continually abscessing during this process, then its time to question your hoof care provider about what methods they are using. Abscessing is not a normal outcome of shoe removal and trimming. Ask an Equine Podiotherapist to assess your horse if you are having problems.

By careful non invasive trimming that removes the excess leverage from the hoof capsule and encourages the hoof shape to slowly grow towards a more normal form, the deformation issues can be resolved without too much stress. 

It may take some time and several trims and it will require the owner to have the horse trimmed no longer than four weeks apart. This is really important! If you leave your trim cycle longer than that you are right back where you started. 

Often as the horse progresses it speeds up the rehab.  if your trimmer can show you how to do some very basic maintenance trimming yourself. Many owners are seeking to attend workshops and learn a basic maintenance trim so that they can take over the ongoing maintenance of their own horse. It really speeds up the rehab process even if you do no more than rasp around the hoof wall in between professional trims.

 

Does the rehabilitating horse need hoof boots on in the paddock?

No, the horse needs to be barefoot in his pasture. He will protect his own feet by carefully picking his way and he needs the stimulation from walking gently around on lots of surfaces to help develop his sole and digital cushion areas. 

When riding a rehabilitating horse you will require the use of hoof boots and pads. Yes, we do sell boots on this site and so would naturally recommend them, but we came to do that because we were for many years first and foremost, hoof care providers and barefoot educators, and found in every case the use of boots and pads speeds up the recovery process.

Boots & pads also allow the owner to enjoy their horse as they always have which is also very important. Restoring good hoof function requires that the internal structures be regenerated and slow gentle ridden excercise helps this happen.  

 

Do you always need pads with boots for rehab?

For horses with depleted thin soles you will need to use pads in your boots. The pads provide comfort and stimulate the tissues above. They also help the horse become brave enough to stride out heel first as he should.

The horses own heavy weight in motion can be a powerful rehab tool. But... without boots they will creep along trying to maintain those toe first landings, looking for heel protection even in boots. They will continue to hunch their shoulders and brace their bodies to protect their feet and this adds to their already existing musculo-skeletal issues and slows down their recovery. With pads inside their boots they relax and load their heels again.

 

Whats all the fuss about avoiding laminitis & founder?

Laminitis is a complex and dangerous condition for any horse. It should never be taken lightly and the warning signs should be heeded to before the horse slips into serious founder.

Laminitis stems from a breakdown in the digestive system which releases metalloproteinase enzymes into the horses system. It can be from any type of insult to the horse's system.

These enzymes destroy the lamellar attachment apparatus that holds the pedal bone tightly to the hoof capsule wall. Once this attachment breaks down the horse's own weight on the toe of the hoof is enough to lever the capsule away from the front of the pedal bone. When that happens the bone may then press down and penetrate the soul. This advanced condition is called founder.

If you have a horse that is a "good doer" then beware if he/she is also overweight. These horses are insulin resistant and are prone to founder. (see www.safergrass.org)  They are only one "insult" away from disaster. The trigger can be as simple as a frosty night changing the amount of sugars in the grasses of their pasture, an illness, a long float trip, retained placenta or access to sugar rich feed.    

Founder is life threatening and catastrophic and even if horses survive, it will take months of painful rehab. before they are able to walk correctly again. (see www.barehoofcare.com)  If you suspect your horse is developing laminitis you MUST call a vet straight away as symptoms don't become evident until the syndrome is quite advanced.  If you feel your horse might be foundering call your veterinarian at once!

If you see the classic  leaning back stance where the horse places both his front feet forward, your horse is in deep deep trouble and is already foundered. There is more information on dealing with founder on www.barehoofcare.com & www.hoofrehab.com.

Is founder linked to Cushings Disease?

There is a wonderful website by Robin Siskel in 1999, co-owned with Dr. Eleanor Kellon, VMD.  It offers support and information for the owners of horses with Cushings Disease and the owners of insulin resistance horses where both are discussed fully and if you have a horse that is diagnosed with Cushings then we recommend that you visit this site.   www.ecirhorse.com/      

What is Cushing's Disease?

Cushing's Disease is a disorder of the pituitary gland and results in hormonal disturbances. The pituitary gland secretes high levels of the hormone ACTH which stimulates the production of cortisol, a stress hormone. This is generally considered a disease of middle-aged or geriatric equines.

What is Insulin Resistance?

Insulin Resistance (IR) is a condition where cells do not respond to insulin, the hormone primarily responsible for transporting glucose into the cells. It is sometimes also referred to as "Equine Metabolic Syndrome" or by the terms "Pre-Cushings" or "Cushingoid" which further complicates obtaining a correct diagnosis. While IR often occurs in the horse with PPID, it is a distinctly separate condition from Cushing's disease and it can occur without Cushing's.

What diets do foundered horses need?

Founder recovery cannot be thought of as just a hoof issue. If you have a laminitic horse you will need to carefully monitor every mouthful of food they have access to for the rest of their life. That includes taking into account what nutrients they are receiving in the pasture as sometimes even the most ordinary grasses are rich in sugars.  If your horse is in pasture that was originally dairy country you need to know exactly what they are eating.  For advice and emergency diets see www.balancedequine.com.au/ 

If you have a performance horse you also need to know exactly what it is missing in its diet...glossy adds on feed bags are not good enough, your horse's entire diet including pasture needs to be assessed.

What is mechanical laminitis?

In performance horses there is often a condition whereby the laminae connections are weakened by continual inflammation from the shearing forces operating on the front of imbalanced hooves.  

This happens to a lot of performance horses working in shoes on hooves set up with a too long break over and can happen to badly trimmed barefoot performance horses too. These horses are constantly tender footed and unable to reach peak performance. They always carry a litany of musculo-skeletal issues and if they suffer an "insult" they can easily pass to the next phase of full blown laminitis.

In the thoroughbred race horse sub clinical laminitis is often linked to inappropriate diets and advanced hoof deformation from their early shoeing practices.

  

How to spot Sub-clinical laminitis:

 

 

 

 

 

 

The picture above shows clearly the horizontal lines that appear in the hoof walls of sub clinically laminitic hooves. These are not growth lines, or stress lines they are signs of serious metabolic distrubances.  Note how they widen at the heels a clear indication of sub clinical laminitis.

 

What do healthy hooves look like? They are truly beautiful!

 

 

 

 

 

 

 

 

How do I find a professional trimmer & boot fitter or Podiotherapist?

For those looking for a professional hoof care provider in their local area who can also supply boots - see our boot fit/hoof care page. 

If you are seeking a specialist Equine Podiotherapist in your area contact equinepodiotherapy@bigpond.com

 

The following is an article written by Duncan Mclaughlin a professional hoof care provider, Equine Myofunctional Therapist,  trainer and competitive endurance rider who shared his personal  insights on a recent esycare inc blog. The article has been widely enjoyed by those exploring natural hoof care. He has given us permission to list his blog article here too.

 

Is Concussion Really A Problem?

Tuesday, February 16, 2010 by Duncan McLaughlin

"Your eye and ideas are not nearly as good as nature's."  James Rooney

We have all seen them, those insidious concussion rings that appear in the hoof wall following an endurance ride, gradually moving down with the growing hoof capsule. Sometimes they even manifest as horizontal concussion cracks. They look ugly and they scream: Damage! And then, there is all that long-term concussive wear and tear on joints leading to inevitable arthritic change. Not surprisingly, managing concussion is often considered the primary soundness issue for your endurance horse over his career.

But need it be so?

To answer this question, let's first consider how the hoof functions. Of course, as any internet search soon shows, there are about a bazillion or so theories on how the hoof functions and how to best manage and dress the hoof for optimal performance. For any one theory of hoof function you will soon find another in complete contradiction. However, all the different theories can be categorised into two basic models based on the distribution of weight through the hoof.

1. Whole Of Foot

Under this model, your horse's weight simply falls, via the skeleton, to the ground through all components of the hoof (wall, sole, bars, frog), which share in the distribution of that weight. The coffin bone is the load-bearing structure. Under this model, factors external to the hoof, such as the amount of daily movement, the living and working terrain, conformational traits, and the presence/absence of hoof protection, are considered to determine which hoof structures are trimmed or left untouched. The aim is to distribute weight across all hoof components, including the caudal hoof (digital cushion, ungual cartilages), to optimise correct coffin bone loading within the hoof in motion and at rest.

2. Lamellar Sling

Under this model, your horse's weight falls through to his coffin bone, which is in turn suspended in a 'sling' by way of the close interweaving of the epidermal (hoof wall) and dermal (inner hoof) lamellae. Under this model, the hoof wall is the primary weight bearing structure, and the focus is on angles and measurements of the hoof in isolation to both your attached horse and his living environment. Obviously this model is implicit in all farriery: attaching a shoe mandates the hoof wall as the only weight-bearing structure. Some vets and researchers also use this model. For example, the work of much-quoted laminitis researcher Chris Pollitt DVM is based on this model, which he describes as the 'lamellar corium - distal phalanx attachment apparatus'.

Most schools of barefoot trimming use methods based on the Whole Of Foot model. Rightly so - there is good reason to be skeptical of the Lamellar Sling model:

1. Despite the extensive area of interconnecting epidermal (hoof wall) and dermal (inner hoof) lamellae, around about a square meter per hoof, there is no reason to believe that, as the primary (or singular) weight-bearing mechanism, this soft tissue connection is able to withstand the repetitive forces generated by a moving horse over a long term performance career.

2. Horses are not intergalactic visitors, without an evolutionary history. No other terrestrial mammal suspends its weight from its epidermis! Horses evolved from three-toed ancestors that distributed weight through the whole of each of their three toes. It is hard to imagine, given this starting point, any type of selection pressure under which a 'lamellar sling' would or could evolve.

Like your horse, giraffes evolved by fusing and lengthening of the bones of the lower limbs but has two toes encased in horn instead of one.

3. More pragmatically, schools of barefoot trimming based on the Lamellar Sling model, for example those based on Hiltrud Strasser DVM's theory of ' hoof mechanism', continue to be spectacularly unsuccessful at producing sound horses able to perform any useful amount of work.

Bone requires loading - it loves to be stressed. But it needs to be stressed along the line(s) of compression for which it evolved. Your horse's coffin bone is his loading hoof structure: trimmers of successful barefoot performance horses trim to the coffin bone. In particular they look to maintain/develop a hoof where the medio-lateral and anterio-posterior balance facilitate quick and easy rotation of the coffin bone during the support-phase of movement (see the previous post on positive dissociation for a reminder on why short stance phases are important) and where the coffin bone sits high in a short hoof capsule.

Trimmed (or shod) in accordance with the Lamellar Sling model, your horse's weight is suspended primarily or solely from the hoof wall. The soft tissue, the epidermal and dermal lamellae, connecting the hoof capsule to the internal hoof are not able to withstand repetitive pressures associated with movement and the hoof capsule is pushed (by the ground) up higher and higher around the coffin bone; the hoof appears long. In the absence of ground stimulation the thin sole and under-developed caudal hoof (frog, bars, digital cushion, ungual cartilages) causes the coffin bone to sit low (digital descent) in the already elongated hoof capsule: There is no compression of the coffin bone, via the sole. Instead, it is placed under tension from the lamellar sling - a quite different force than the compression forces the coffin bone evolved to cope with. The distal phalangeal joint (between the short pastern and the coffin bone) is encased within the long hoof capsule, reducing range of motion.

Further, to move optimally, the coffin bone pivots over a specific balance point in the hoof, above the pericuneal cortex, during support-phase of movement. When your horse has a long toe, the extensor processes of the coffin bone elongate in an attempt to rebalance the hoof and maintain position of this pivot point. This results in what we commonly call under-run heels: It is not necessarily that the heels are actually under-run but that the extensor processes of the coffin bone have elongated backward, over the heel, in an attempt to balance the long toe.

 

Trimmed in accordance with the Whole Of Hoof model, your horse will have increased concavity, sole thickness and caudal hoof (frog, digital cushion, ungual cartilages) development within a relatively small hoof capsule. The coffin bone sits high in the hoof capsule with the happy consequence that the distal phalangeal joint is about level with the coronet band, enabling that very fluid movement peculiar to barefoot horses.

The focus using the Whole Of Foot model is not how much the hoof wall (or any other hoof component) is loaded or unloaded, this depends on a range of factors, but to ensure the coffin bone is correctly loaded. As a rule of thumb, we want the hairline above the extensor processes of the coffin bone to be around 10mm distance. If this distance is 14mm or greater, your horse clearly has a descended coffin bone (digital descent).

 

Despite the very long walls on the foot of this soft-terrain living Cumberland Island feral horse, correct anterio-posterior balance is maintained. The long heels balance the long toe to ensure correct pivot point and the coffin bone is still loaded as the very soft terrain provides a 'solar plug' which fills in the area under the sole between the wall. In addition the wall at the toe cuts into the soft ground, allowing full range of movement without excessive dorsiflexion of the fetlock. Photo from Cindy Sullivan's Tribe Equus website.

Our discussion about concussion and hoof structure must include mention of the bars. For our performance horse, we want short, straight bars that bear load during support-phase. In a well developed hoof the ungual cartilages are thickened with fibrous cartilage that sits over the bars. On weight-bearing the bars are pushed up and work in conjunction with the ungual cartilages to expand the top of the hoof. Loaded bars are also involved in the transfer of energy to the digital cushion. Bar loading is vital for reducing concussion (as your good footed horse actually experiences negative pressure in the hoof on heel strike, it sucks onto the ground - refer to Prof. Robert Bowker's work on good footed horses for more detailed explanation). Those trimmers who are misguidedly excavating bars in order to relieve 'navicular syndrome' or wall flares at the quarters, are actually increasing concussion and preventing caudal heel development. No amount of trimming can develop short, straight, functional bars. Functional bars result, as if by magic, when the coffin bone is carried high in the hoof capsule; a result of well developed soles and caudal hoof structures.

Similarly, it is not possible to trim concavity into the sole. Again, concavity arises when the thick sole and well developed caudal hoof push the coffin bone higher in the short hoof capsule. Carving out concavity in a parody of correct hoof function simply thins the sole further, preventing your horse from performing any useful amount of work. In particular, the sole under the coffin bone, rich in proteoglycans that function to hydrate the solar tissue and so absorb concussion, should not be compromised.

So, trimmed by methods that accord with the Whole Of Hoof model, your horse will move in a biomechanically correct and comfortable manner. But what do we mean by 'moving comfortably'? In a recent internet chat-group discussion, one observer of Australia's desert brumbies mentioned that some of these horses would take 'ouchy' steps when trotting on rocks and gravel. The implication was this was a bad thing, in which case, this observer misses the point. The fact that desert brumbies take some ouchy steps actually demonstrates extremely effective hoof function. When I take my shoes off and go for a run, I can stride along quite comfortably but if my foot begins to land on a sharp rock, I immediately take an ouchy step - I limp- as sensory nerves instigate a reflex action to prevent my foot from weight-bearing. The ouchy step is the perfect (though energetically inefficient) way to move when treading on a sharp rock and prevents both me and the brumby from getting a bruised sole. It certainly does not mean either of us are unsound or in pain. Indeed, failure to take an ouchy step when treading on a rock is, or should be, the real concern; go watch the shod horses at your next endurance ride…

The same sensory mechanisms explain why terrestrial mammals take longer steps on soft ground compared to shorter steps on hard ground. When landing on a soft surface the hoof instinctively comes down harder in order to load the coffin bone and to find a stable platform to support the support-phase: cushioning (turf, sand, padded boots or shoes) reduces sensation, not concussion. Your barefoot horse, trimmed to appropriately load the coffin bone, trotting with shorter strides on an tar road demonstrates the correct biomechanical form and function to dissipate concussion. On a softer surface, say a grassy field, he will need to move with a more lengthened stride - that is, increased force - in order to correctly load the coffin bone.

Accepting that his movement will change on different surfaces, you should always remain alert that your barefoot horse travels in a comfortable manner. Anytime your horse is not moving comfortably, for example, continuing to tip-toe along a gravel road, he is using muscular effort to change his way of going. This is not only an incredible waste of energy, with potential for muscular overuse injury, but also puts improper stress on bones and joints: joint injuries are not overuse injuries, they are improper use injuries where muscles, via tendons, inappropriately strain the bones comprising the joint. If your barefoot horse is struggling in anyway with the distance or terrain you ride him over, you should boot him.

A number of boot models are appropriate for endurance horses. I prefer the Easyboot Glove for endurance (and whenever possible for rehabbing horses with laminitis, 'navicular syndrome', and similar hoof pathologies). I particularly like the Glove because:

1. Rubber is the ideal surface to encourage perfusion of blood through the hoof. In his lecture to students in the 2009 Diploma of Equine Podiotherapy, Prof. Bowker discussed how the hoof interacts with a rubber surface, increasing surface area (more than on any other substrate). Even small increases in surface area will drastically reduce overall pressure.

2. The firm rubber surface evens out the actual terrain the horse is moving over. On soft terrain such as deep turf or sand, the rubber provides a more resistant landing preventing the limbs from hyper-extending in an attempt to find a stable landing place. On very hard terrain such a rock or tar, the rubber creates a more cushioned landing, allowing your horse to move out comfortably with lengthened stride, which is much less fatiguing for the rider.

3. There is a good breakover, relative to the solar area, moulded into the boot (the breakover is much better than the breakover of the actual hoof for the majority of domestic horses). As discussed previously, a quick breakover ensures correct biomechanical action, including heel first landings. Comfortable heel first landings are the way to develop the caudal hoof. Stimulation of receptors in the frog, heel bulb and ungual cartilages encourage development of the digital cushion. The digital cushion of horses with no frog, sole and heel stimulation is a weak mass of connective tissue. By contrast, stimulated with whole-hoof ground-contact and heel first landing, the digital cushion develops a web of fibrous cartilage that radiates out and up from its origin near the junction of the deep digital flexor tendon with the coffin bone. On a well developed hoof this fibrocartilagenous web extends up past the navicular bone and creates a resilient floor across the entire base of the digital cushion. More fibrocartilage means more energy dissipation and less concussion. Further, the ungual cartilages of the coffin bone also lay down (thicken with) fibrocartilage in response to stimulation. Well developed ungual cartilages approach an inch in thickness and are crucial in reducing concussion as only thick ungual cartilages encase intricate complexes of blood vessels within: these act as hydraulic energy dissipaters. When these complexes merely sit along the internal edge of thin ungual cartilages, their function as shock absorbers are compromised. Ideally, you want your horse to have close to one third of its hoof volume taken up by these caudal hoof components. In shod horses the caudal hoof volume is commonly less than 20% and sometimes as little as 10%. Used on a horse with a well developed caudal hoof, as found with many barefoot endurance horses, I will further rasp back the Glove breakover a few millimeters more to create an improved boot breakover for working horses - this saves waiting for the breakover to wear in over time.

4. The comfort provided by the boot means the horse can be ridden more. More steps means more blood perfusion through the hoof and more development of the caudal hoof. In effect, you can ride your horse to increased soundness (the opposite of the traditional view that an endurance horse only has so many miles in him).

GE Lady, at the end of a hundred mile ride, wearing Easyboot Glue-Ons with solar packing. Despite a strenuous and rocky 100 miles, Lady continues to move with positive dissociation. Her soft and relaxed musculature, in particular the raised withers and forward reaching poll, indicate continued excellent biomechanical form despite her exertions.

Of course, it is not all sweetness and light. All hoof boots have a flat inner-sole. If most of your horse's time in action is spent in boots (as is often the case for endurance horses, who cover much more ground in training than when loafing around the paddock), you will see the hoof adapt to this flat surface; primarily by losing concavity. The coffin bone does not want to 'bottom out', that is, over-descend (and come into tension as per the Lamellar Sling model), as is possible with a concave foot on a hard, flat surface. The sole with thicken further, particularly in toward the frog, filling in the concavity. Not in itself a problem except that this extra thick sole has potential to overload the coffin bone when your horse is unbooted. For many boots, the issue is avoided completely by using a dome pad as a 'solar plug', providing an artificial terrain that maintains concavity (in fact dome pads are so effective at this I have often incorporated them in the recovery of laminitic horses to riding soundness). Dome pads are not available for the Glove but it is easy to create custom pads for your horse using Goober Glue.

Further, cushioning reduces sensation not concussion. Booting, and particularly booting with pads (of whatever form), reduces the sensory feedback from the hoof. More than likely your horse will want to really stride along when booted. It is appropriate for you, as the rider, to slightly temper this more extravagant movement and somewhat contain his length of stride. But don't worry too much. So long as the boot allows (or even improves) correct movement (reducing support-phase, lengthening flight phase) then any increased concussion forces are easily dissipated according to nature's design.

Remember, it is correct biomechanical form and function that dissipates concussion - get these right and concussion simply ceases to be an issue, no matter how many miles you ride.

******

Hoof Dressings, Hoof oils & other applications for the hoof wall:  There are many hoof dressings on the market.  Both commercial and home made.  They just don't work as a cure for isses such as hoof cracks. The solution is creating a physiologically correct hoof and removing the leverage forces that create the cracks, and offering a good diet, both need to be supplied on a regular basis!

 This exert below from a summary of a study by P Wagner DVM & Susn Kempson BScPhD.

  Hoof Dressings: What Studies Show
By: Marcia King
Originally Printed in: The Horse (Article #3840)

Hoof dressings aren't always what they're cracked up to be--at least not in the opinions of some experts. Ilka P. Wagner, DVM, owner of Equine Veterinary Services (Texas), and Susan Kempson, BSc, PhD, senior lecturer in Preclinical Veterinary Sciences in the Royal (Dick) School of Veterinary Studies at the University of Edinburgh, have studied the efficacy of hoof dressings. Robert Sigafoos, Certified Journeyman Farrier, chief of farrier services and director of the Applied Polymer Research Laboratory at the University of Pennsylvania's School of Veterinary Medicine, bases his opinions (self-described as "subjective") on 28 years of experience.

Purpose of Dressings
Hoof dressings are promoted to remedy cracks, splits, moisture loss, and associated lameness. Says Wagner, "Hoof dressings are commercially (prepared) or homemade external hoof wall applications that are 'reputed' to be beneficial to the growth, metabolism, and overall health of the equine hoof wall. Many products make label claims that they encourage hoof wall growth, strength-en the wall matrix, and even go so far as saying they prevent laminitis. They are available at most feed stores as well as over the Internet to the horse owner."

There are three types of hoof wall dressings that claim to preserve moisture of the hoof wall. Wagner identifies them as:

  • Primarily petroleum oil-based--These are usually "gooey" or tarry products. Ingredients might include neatsfoot and/ or cod liver oil, pine tar, petroleum compounds, and/or turpentine.
  • Primarily lanolin-based--These are usually more the consistency of hand lotion. Ingredients might include lanolin, lactates, stearates, alcohols, and glycerin.
  • Primarily containing a drying agent--Ingredients might include acetone.

The question is, how well do they work?
Hoof Permeability
Sigafoos has used some hoof wall products principally to manage hairline cracks at the coronary band, a problem that is very common in Standardbreds. "I have had some success in using prescription dressings that contain antifungal agents and steroids to control fungal infections at the coronet," he says. Otherwise, he believes that hoof dressings are of "limited value" for acute or chronic hoof problems.

Kempson has investigated the effects of hoof dressings on hoof wall by examining the permeability barrier in the hoof capsule and factors that influence it. "This work started in the mid-1990s and is ongoing," she reports. "Before I could look at the effect of hoof dressings on the horn, I had to investigate the permeability barrier in the horn."

Just as there is a permeability barrier controlling passage of water and water-soluble materials into and out of the skin, so there is one in the hoof horn. To study this aspect of the hoof wall, Kempson used water-soluble tracers visible with both light microscopes and electron microscopes. "The tracers are small molecules that travel with the water into the horn," she explains. "If the water can get into the horn, then it could also get out! The water could either travel between the cells or through the horn cells, or a combination of both."

She took full-thickness blocks of horn from dorsal walls, soles, and frogs of feet obtained post-mortem. She compared good-quality horn with poor-quality horn (i.e., horn with cracks).

"In feet with good-quality horn, there was virtually no penetration of the tracers and water through the outer pigmented layer of the dorsal wall," Kempson found. "There was some penetration through the inner non-pigmented layer of the wall both through the intercellular spaces (between cells) and through the cells. This indicated differences in the permeability barrier between the inner and outer layers of the wall. In a normal hoof, the inner layer is not exposed to the environment and is therefore unlikely to lose or absorb water through this horn. There was more penetration of the tracer through the sole horn and even more through the frog horn, but this was still only limited to a few cell layers--five to eight cell layers in the sole, and 12-18 cell layers in the frog, which is less than one millimeter."

Her findings regarding poor-quality horn were quite different. In these walls, the water and tracer penetrated deep into the pigmented layer and spread through the intercellular spaces and into the non-pigmented horn.

As part of the study, Kempson also examined how environmental conditions could affect hoof wall integrity. "Having spent several years studying the effects of nutrition on the hoof capsule, it became clear that the environment was also having an influence on the integrity of the horn," she explains. Therefore, Kempson looked at the effects of feces, urine, hoof dressings, heat, cold, and water--the various elements to which horses' hooves could be exposed.

For two weeks, blocks of wall, sole, and frog were either left in the test solutions, heated to 98.6°F (37°C), chilled to 39.2°F (4°C), or left in water. Afterward, they were exposed to the water-soluble tracers.

"The results were surprising," Kempson says. "Heat, cold, and water had no effect on the permeability barrier. The sole and frog horn left in feces for two weeks disintegrated, and poor-quality wall horn was also badly affected. Good-quality wall horn was only marginally changed. Urine alone had little effect, but combining urine and feces had the same results as feces alone.

"My conclusion is that the horn has a built-in permeability barrier," she says. "As long as the horse has a well-balanced diet so that he can produce good-quality horn, leave the hoof horn to look after itself."

Hoof Dressing Research
Formalin is extensively used as a biological fixative for routine histology, preservation of cadavers, etc. It can also be used as a disinfectant because it kills bacteria. When Kempson applied dressings containing formalin to the hoof samples, there was no change in the permeability barrier of either good or bad horn samples.

"Formalin causes the horn to lose its plasticity, and it becomes brittle and more liable to crack," she states. "With horn of poor quality, the formalin-based dressings penetrated deeper into the horn than in the good quality feet. This meant that the micro cracks caused by the formalin extended farther into the tissue and this let water and other materials penetrate the horn. The damage caused by the formalin-based dressings was greatest in the sole."

Poor-quality horn treated with formalin thus becomes more susceptible to infectious and toxic agents, and therefore this chemical is best avoided.

The study also showed that hoof dressings containing solvents and tar-based components damaged poor-quality horn. In some cases, the intercellular lipids or fats were damaged, allowing water contained within the horn to evaporate, thus causing the horn to become dry and brittle. In very wet conditions, using these hoof dressings allows water into the horn, and the feet become very soft and weak.

"When these products were applied to poor-quality horn, the damage was magnified, and I could not get results from some of the tissues because they had disintegrated in the test solutions," she notes.

Good-quality horn was affected in the same way, but it took longer for the effects to be seen. "It was also clear that the majority of the dressings that horse owners applied to the hoof capsule did much more harm than good. Most are unaware of what they are doing to their horse's feet. They apply the dressings with the best of intentions, but more research needs to be done to clarify the situation."

Wagner participated in two separate hoof studies done at Texas A&M University. One in vitro (outside the body) study was to determine if hoof wall dressings could alter the hoof wall moisture content under controlled laboratory conditions. The second in vivo (in the living body) study looked at the ability of certain products to change the biomechanical ability of the hoof wall to withstand certain stresses.

Previous research showed a relationship between relative hydration of the hoof wall and its mechanical properties. Wagner says, "If the wall suffers from dehydration or overhydration, it will become more susceptible to developing cracks and splits."

Thus, Texas A&M University researchers sought to evaluate the relative efficacy of commercial hoof wall dressings in maintaining hoof wall hydration. Researchers took hoof wall samples from 10 clinically normal, sound horses within 24 hours after euthanasia (they weren't killed for this study). "We coated these samples with 15 different products, let them dry over 48 hours, and measured the samples at certain intervals," Wagner says. The products were either mainly oil-based, lanolin-based, or contained mostly acetone.

"We did calculations to determine sample moisture content changes to see if these products could maintain the moisture content that was already there or increase it," he says.

Data indicated that several products under ideal conditions could maintain hydration of the wall for 12 to 24 hours. Control samples without the dressing lost much more relative moisture. When the three groups were compared, those products maintaining the highest degree of relative hydration in the hoof wall at 24 hours were primarily the oil, pine tar, and petroleum-based products, says Wagner.

"However, that's not necessarily a good thing because you can over-moisturize the wall and make the wall less strong than it was to begin with," he says. "Too much can be bad. I think there are situations in which it is apparent that the hoof wall is exceptionally dry, but that could have been an adaptation to the environment and not necessarily a bad condition for the hoof."

Hoof wall achieves its maximal fracture toughness when relative hydration is maintained at approximately 70-75% moisture. However, studies are needed to evaluate the best hydration level. It's important to remember that environment will have a significant effect on hydration of the hoof.

The researchers warned that results shouldn't be directly extrapolated to living horses, as normal horse movement can physically remove the dressing from the hoof wall, thus reducing its efficacy.

"In addition, the internal environment of the horse's foot may contribute to maintenance of natural hoof wall moisture as well," Wagner notes. "Obviously, this was not a contributory factor in this study."

The second study in which Wagner took part examined whether commercial hoof dressings could affect hoof wall strength in live horses. This study used three selected products applied to the feet of five horses for 13 weeks--a different product for three hooves with the remaining hoof used as a control. These horses lived in normal conditions, being exposed to rainy and dry weather conditions. For 13 weeks, lanolin-based and petroleum-based products were applied twice daily, while the acetone-based dressing was applied once a week (per label recommendation).

"At the end of that period, we took strips of hoof wall samples to the engineering department to measure the strength of the hoof wall," he says. "A lot of products claim they can change the protein structure and strength of the hoof wall; none of them made any difference. They didn't show any kind of change in the elastic modulus (flexibility of the hoof wall)."

However, the study notes that it's "still possible that these products are affecting the wall, but only to a certain degree. They may be influencing the outer hoof wall, which may not be evident in this study due to the use of full-thickness wall samples."

In reflecting on the studies, Wagner says that hoof dressings "are often prescribed for conditions in which the hoof problem is more likely due to a genetic problem of poor hoof wall metabolism, growth, or matrix that simply cannot be changed."

Need to know more about natural hoof care?

These are some more wonderful hoof related sites.