Dr. Robert Bowker on Navicular Disease

I was very excited to have the opportunity to interview Dr. Robert Bowker last week.   He’s one of the few researchers who has dedicated his life to learning all he can about the function of the foot and has led the way in changing the way many of us view the horse’s foot.  His studies on blood flow and energy dissipation in the equine hoof have been of particular interest to many—especially those involved in the barefoot hoof ‘movement’.

Dr. Bowker earned his veterinary degree at the University of Pennsylvania’s College of Veterinary Medicine in 1973 and then completed his PhD degree in neurobiology in 1979.  He currently teaches anatomy at the College of Veterinary Medicine at Michigan State University, where he has been since 1988.

Although much of Dr. Bowker’s research continues to be ignored by those in traditional veterinary and farriery circles, he pushes on, continually bringing to light the misinformation that is often printed in student and veterinary texts.  The evidence he has collected on the natural function of the foot is overwhelming and is cited time and again by natural barefoot trimmers and holistically-focused veterinarians.

I’m reminded of a favorite quote of mine when I think about Dr. Bowker and his work:  “All truth passes through three stages. First, it is ridiculed. Second, it is violently opposed. Third, it is accepted as being self-evident.”   ~Arthur Schopenhauer

I absolutely believe that the truth about horses’ feet will soon be accepted as being self-evident.  And we have Dr. Robert Bowker to thank for much of that.

 Q&A with Dr. Bowker: Navicular Disease

 Dr. Bowker3

 

What led to your interest in studying the equine foot and navicular disease in particular?

I’m a neurobiologist (scientist who studies the cells of the nervous system) by training, and in the early 90’s, I was asked by students what nerves might be desensitized with local anesthetics.  We started to investigate where the nerves are and where the local anesthetic disperses to once injected and we began mapping out the nerves that are affected by this procedure.  This, at the same time, caused us to dissect and to learn the anatomy  of the foot  more thoroughly.  Eventually we were led to focus on the tissues and potential ideas specifically related to navicular disease.  I wanted to understand how the foot responds to impact with the ground and to how the energy was dissipated as well as how the tissues respond as well.

I started measuring different parts of the equine foot and I noticed that in many horses, the lateral cartilages were underdeveloped.  I also noticed that by the time radiographic changes in the navicular bone were evident, the condition had actually been present for years.  In retrospect, I was very naïve in my way of thinking because now we realize these small lateral cartilages were not underdeveloped (e.g. did not have an opportunity to grow and develop) but they were undergoing varying degrees of degeneration or severely being affected by the vibrations upon the heels and feet hitting the ground.

One thing that I think is important to mention is that I didn’t grow up with horses.  And because of this, I wasn’t ‘biased’ as so many people are when it comes to horses’ feet: the common “horse lore” or dogma regarding their feet was not in my veins!

 

It seems there are numerous definitions of what navicular disease really is.  How would you define it?

navicular_diagram_1

Navicular disease is used to describe any soreness in the back part of the hoof.  A hoof tester used on the frog is a pretty reliable indicator (supposing thrush is not an issue).    There are multiple causes of navicular and everything from the coffin bone and the back portion of the foot can be affected.  The navicular bone and the deep digital flexor tendon can be fine, but the horse can still have navicular pain.  By the time any abnormalities show up radiographically, you’re pretty far down the road.  I see it as an A-Z continuum, and you’re usually at W-Z by the time changes are actually seen on radiographs.

 

According to your research, how does navicular disease come about?

From my studies, I’ve been led to believe that it’s our husbandry practices–the way we care for our horses–that have created navicular disease.  Essentially, navicular disease comes down to vibrations; vibrations destroy tissue in the foot.

How does this happen?  When horses are made to live on or if they are worked continuously on hard surfaces, the frequency of the vibrations increases.  Even vibrations as low as 250-300 Hz can destroy connective tissue, but it’s been shown that horses stopping on hard ground can undergo vibrations up to 3000 Hz.  My belief that hard surfaces, shoes, our husbrandry practices, and our methods of trimming or shoeing are the main culprits for these increased impacts/vibrations upon the feet.

Shoes also increase the frequency of vibrations in the foot.  Tissues can only absorb so much energy before the bones then start to deteriorate.  One study, from 1988-89 performed in the Netherlands, showed that horse shoes can increase the vibrations up to 2500 Hz.  So yes, shoes play a definite role in the development of navicular.  But having said that, even a barefoot horse living or working on hard surfaces can develop navicular.

 

Can you explain what happens to the foot if the frog does not come in contact with the ground?

Basically, things go to hell!  I believe the worst thing you can do to the foot is trim the frog.  When you trim the frog you are taking away the exterior part of the foot which affects the underlying interior of the frog enormously.  The frog is a highly-engineered structure with an enormous blood supply–it contains thousands of small micro-vessels.  These blood vessels are crucial for proper blood flow and for the health of the hoof.

When the back part of the foot and frog are not on the ground, the impact energy (from movement) is not dissipated but is instead transmitted to the bones and other connective tissues of the foot. These tissues do not dissipate the impact energy well, and the long-term result is chronic foot problems and lameness.

If the frog is on the ground, the bars will contribute in supporting weight and much of the load will be supported by the sole.

I also think the dirt that becomes packed into the bottom of the hoof plays a role in helping to support the foot.  You shouldn’t clean out this dirt (unless it’s manure).  In my experience, thrush only becomes a problem when the horse is in a stall.

 

Is Navicular disease reversible once deterioration of the navicular bone has begun?

It really depends on the level of damage.  Tissues can heal, but they may never be normal again.  Navicular is linked with such a wide range of pathologies and every horse is different.  In many cases, the toes are left too long though.  Having a short toe is crucial for healing.

It is a mistake to believe that the hoof wall should support the horse, as traditional farriers and many veterinarians believe.  The entire sole as well as the structures in the back of the foot should support much of the horse.  The coffin bone (which lies directly above the sole) should be loaded all the time.  It should be dense.  If the coffin bone is not loaded, it will become porous—this is not a good thing.

I’m currently working on research which focuses on rehabilitating navicular horses.

 

In your opinion, should shoes ever be applied to a horse with navicular disease?

Well, that depends on what you want.  If you are discussing normal active horses and you want the tissues to continually become more robust, then probably no.  But if you are competing, etc. and there are rules, then you will need to apply shoes of some sort. The foot needs to be protected somehow depending upon what it is doing and how you are trimming the foot.

Any time a shoe is put on a hoof, we need to take responsibility for the impact that the shoe is having on the hoof and the remainder of the foot. Few people actually take this responsibilty in my opinion.  It’s our husbandry practices that are incorrect and creating problems like navicular.  If we correct those, the hooves will follow suit.

I do not have all of the answers but I see more feet in varying degrees of deterioration than I do healthy feet! A sound foot, in my opinion, is not necessarily related to a healthy foot; it only means that it is not lame at this point in time.

 

Any final thoughts?

Many people think that barefoot is just about pulling the shoes off.  It’s not.  Proper and frequent trimming and keeping the toe short will result in a good hoof. In my opinion the foot during the active growth season should be trimmed by a trimmer or farrier every 3-5 weeks. In some cases even shorter time intervals. Rarely longer though.

Horse owners have a responsibility to become educated—and they need to start by paying attention to the foot.  I consider proper foot care and nutrition to be the two most important aspects of horse care.

 

 

Casie

Hi! My name is Casie Bazay. I'm a mom, a freelance writer, and a certified equine acupressure practitioner.

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17 Responses

  1. Jill Mora says:

    Another great article! Thanks so much for sharing this excellent information!

  2. Linda King says:

    Interesting reading. My German Warmblood was noticeably lame the second day after I got him, he was diagnosed with severe advanced navicular disease, that was in 2005, so he will be in your W – Z scale, he is still going strong, so having nav is certainly not the death sentence it used to be. thanks again for your information

  3. Hans Wiza says:

    This is a very well presented article and rationale for the causes of Navicular disease.I been a professional farrier for 45 years. In this time I have rarely had a horse in my clientele diagnosed with Navicular disease. Some of my colleagues have a significantly higher rate of diagnosed Navicular disease. In my opinion the way a hoof is trimmed whether barefoot or shod is the most crucial aspect of the hoof care process. Hoofmakeover.ca has produced tutorial videos that simplify and demystify the trimming process so that anyone can learn how to recognize and attain the necessary target points that enable a horse to remain sound throughout its career. I have shod hundreds of horses that lived and worked well into their thirties very sound and healthy.

    • Joanna says:

      Yes! Angle is everything! My personal belief is that a horse with a straight shoulder who is shot too low in the heel is a prime candidate for navicular. The Deep flexor tendon pushing on the bone from being stretched out too much inhibits blood circulation

  4. pologirl says:

    Though I don’t disagree with some of this insight, I had my horses barefoot for nearly a year. (dressage horses). You couldn’t have asked for a better footing situation as it was varied (nice arena, pebbles, DG, grass), they were on good diets (no processed feed etc.) Though their feet showed some nice changes and Improvement they were unable to stay barefoot for the long haul, too much sole loss, not enough wall led to sore feet. (and booting got old after 9 months) So despite best intentions shoes were the better way to go. Now we just pull several days in advance of new shoeing cycle to encourage foot to stay open and increase circulation etc. So far so good…happy horses.

    • James Marshall says:

      Hi!

      I’m a farrier with 23 years experience of looking at horses feet. Some years ago, we had 3 personal show horses, which we had purchased from the Springhill L.A. area. Nice sandy, soft, lazy horse soil.

      I had an Impressive bred mare with hoof wall so thin, you could not drive a nail without quicking her. I also had two other horses with white socks, white feet, and so much refined Quarter Horse breeding, their feet had lost all functionality.

      After months of my trying to keep shoes on to no avail, I, after reading an article in the American Farriers Journal about farrier Jean Ovineck, and his recomendation to pull shoes of horses with poor hoof wall quality, I did.

      And boy I’m glad I did! That Impressive mare who’s foot you could not drive a nail into… Well in 6 months, her hoof wall went from 0 to 3/8″ wide, and in time, became over 1/2″ thick.

      And every other horse I had, their hoof wall improved, their feet became tougher. I had no more flat feet, but nicely concaved, thick soles. The feet actually pulled up into themselves, becoming more compact, a leaner, meaner hoofing machine.

      I’ve had success with barefooting my horses, but I’ve a secret I used to be really ashamed of, but as the years go by, I’ve come to value. I’ve a very rocky (with capital V) pasture. My horses live in the North West Arkansas Mountians, with rocky terraine similar to desert.

      Also I didn’t boot my horses. I pulled their shoes, threw them into the pasture and told them to live or die. They lived! And became extrememly healthy hoof because of it.

      But I had to watch my horses limp for about 5 months. At about 6 months things turned the corner. The limps went away, and the hoof walls showed up

      What people don’t realize is you’re not just rebuilding a foot, you’re rebuilding a whole horse, anatomically, digestively, and in the blood circulatory sense from the foot up. We cannot just throw the shoes away, and in 6 months think we can ride these animals barefoot. It won’t work!

      You have to recondition your animal to be tough as nails! Create a live or die environment. You have to put the horse into an enviroment (as in the wild) where if he does not heal, he knows he will die. Only then, can we begin to right the wrongs done to our horses by hundreds of years of breeding them to our percieved idea of beauty, at the cost of equine health and function.

      But this requires dedication, and a tough heart. I’m a farrier, and I’m a pretty good observer of horse owners. Many owners see their horse limp, and hurt more than their horse does. We horse people have to come to understand pain is good! Pain means you’re alive. Pain also means the body is operating in a normal sense, sending nerve signals from brain to limb and back, all body parts communicating, the need for care, nutrients, and the need for suvival.

      Had my horses not hurt physically, they never would have grown a better hoof wall. They never would have been able to go barefoot without shoes.

      We humans in this last century, have forgotten what it means to gut it out until we’re tough enough. We tend to live our lives through our horses, treating them, like we would treat ourselves. With drugs, painkillers, Nyquil, cough syrup, and lot’s of pillows.

      You do that to a horse, and his feet will be as soft as Downy, and his immunity to pain, infection, and hardship will be non existent.

      It’s time we treat the horse as God intended. Treat the horse like he really is! The horse is a battle tank, and always has been.

      A tough, rough, powerful animal which should be respected!

      Instead of soft bedding and a stall, give that horse 30 below 0 and a hard northwest wind! And that horse will prosper!

      • Christine says:

        This was fantastic to read, and I have to completely agree. I have seen many horses with the most rubbish feet make a complete turn around when given the right environment and diet. They adjust, mostly it just takes time and very little meddling.

  5. melva thomas says:

    My horses are barefoot, compete in dressage, jumping and sport horse under saddle. I have not any lameness and they do very well in the ring. I had a mare develop laminitis 8 years ago & after that struggle to get her well and a lot of research in hoof and equine care I arrived at the understanding that iron shoes did not need to be nailed to my horses feet. My horses have regular, proper trims, controlled NSC diets, lot of exercise, pea gravel in the dry lot & turned out in pasture every day. They are rode 4 days a week and compete barefoot at a couple shows a month during show season.

  6. kim says:

    Hello! My 7 year old horse was just diagnosed with the starts of Navicular. My Vet- farrier is recommending shoes. She has never been in shoes always barefooted and is never stalled living out side on 45 acre pasture. He is recommending to put her on Cosequine. Any other suggestion for early prevention…or treatment with supplements. Thank you, Kim

  7. Tammy HALDEMAN says:

    Look into Hoof cinches

  8. MJ says:

    I am wondering about the vibration part deteriortating hoof tissue. I am demoing a Theraplate. I’ve read that that can be beneficial to hoof and all body by creating more circulation. Comments please.

  9. lisa says:

    my horse that is 9 years old was diagonosed with ring bone, I am sooo sad and upset. I changed his shoeing and put him on equiflex and adequan. He is doing well with that but I cannot lunge him or put him in the bull pen. he gets super sore if he is lunged. I love my guy and dont want him to hurt. I am scared about what the future holds for us. I dont hink I will ride him anymore. He will be our pet and be turned out. any advise or knowledge and or experience with ring bone would help. He also has bone spurs on his navicular. this has has barley been ridden his entire life! It must be the hard ground! or heridetory.

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