Firstly some quick links to important hoof care information for those in a hurry!

• Need to know more about natural hoof care? These are some more wonderful hoof related sites. For learning to trim: www.barehoofcare.com
  
• For help with serious laminitis & navicular issues: www.barehoofcare.com For those who need emergency diets for laminitic & foundered horses www.balancedequine.com.au/
  
• For gaining an understanding of how our pastures affect our horses: www.safergrass.org
  
•  For anyone who has "good dooers"! You actually have an insulin resistant horse - find out more now. www.safergrass.org
  
•  For those who want to provide the perfect diets for barefoot horses: www.balancedequine.com.au/
  
• For those who need to tackle their own rehab or can't find a trimmer. www.hoofrehab.com.
  
•  For those who want a career as a professional hoof care provider: www.equinepodiotherapy.com.au
  
• The Glass Horse dvd - A wonderful interactive anatomy tool that allows you to investigate the hoof and all its components and rotate them in 3D views. A wonderful teaching tool. www.3dglasshorse.com/
  
• For hoof information & a guide to saddle fit - see our page on this site featuring tips on saddle fitting written by an Equine Myofunctional Therapist.
  
•  For info on Cushings Disease and Insulin Resistance. www.ecirhorse.com/
  

An overview of Hoof Problems

Michael Ware, Equine Podiotherapist & Director

of the Australian College of Equine Podiotherapy. 

www.equinepodiotherapy.com.au 

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:

 dc

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 internal 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 for life.

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 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 (back of hoof) 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.

Research:

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:

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 years ago 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 now that we now actually blame the horse's breed for his hoof problems!

This assumption stops us looking for solutions to many horse's hoof problems and causes us to fail to recognise what members of certain breeds share in common apart from their genetics.  We need to ask were they shod early in life before their hoof bones matured? Were they given an unnatural upbringing without access to varying terrain and lots of movement?  Were they fed diets that were not suitable?  This is especially true in the Thoroughbred industry.

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?

Secondary Postural and Gait issues from hoof deformation:

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 biomechanically 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"  and the braced stiff hind quarters, 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 state of laminitis 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 www.easycaredownunder.com.au

Hoof Oils - Do they really work?

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, nor do they change the hoof for the better in any way!

The solution for brittle hooves, comes from hoof health.  By 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!

The article below is 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."