Navicular Syndrome

Navicular Syndrome in Horses - Explanation, Causes, Symptoms, Diagnosis, Treatment, Prevention


The Most Common Question: Are Navicular Syndrome & Navicular Disease hereditary?

The most correct answer is: "Navicular Disease "may" be hereditary, since the cause or causes are not clear but there is pathology and it is not contagious, whereas Navicular Syndrome is "probably not" hereditary since the cause is understood, treatable, reversable and curable if caught before permanent damage is done. What is often quasi-hereditary is that a horse may have desirable attributes making it suited to be used, handled, treated, worked, fed, trained and shod or trimmed in the same way as one or both of its parents, for example, a high-performance race horse or a champion Western-Ridden Horse. We see trends in Race Horses and Western-Ridden Horses who have similar hoof angles and generally the parent was trimmed or shod in a similar way for similar cause and we know that certain trimming and shoeing styles do cause Navicular Syndrome. Changing the foot angle to a more natural one can cure Navicular Sydrome.

What's the difference between Navicular Syndrome, Navicular Disease and "Caudal Heel Syndrome"?

Since people often use the terms interchangeably, I'll first explain the difference and why the confusion occurred.

Navicular Syndrome

Navicular Syndrome is a progressive condition affecting any one or all three of the Navicular Bone, Navicular Bursa or DDF/DDFT (Deep Digital Flexor Tendon) at the Navicular Fulcrum** in the Horse.

The Navicular Fulcrum** is not an official term, but refers to the general area or point where the DDF/DDFT bends around the Navicular Bursa and Navicular Bone and is an area of high pressure.

The key distinction between Navicular Syndrome and Navicular Disease is no bone pathology is present in Navicular Syndrome (explained in detail in the Navicular Disease section below). Navicular Syndrome presents no clearly defined visible proof of abnormalities in the Navicular Bone itself consistent with past confirmed cases of Navicular Disease, even though pain response testing for Navicular Syndrome and Navicular Disease may yield similar or identical results. Recently it was proved that Navicular Syndrome has a very simple cause and a very simple treatment and cure.

Correcting the cause and achieving a Cure of Navicular Syndrome as outlined in the ebook above is cheap, requires no drugs or special shoes and generally results in a complete cure within a matter of weeks. For Navicular Syndrome, many vets prescribe Isoxsuprine. Its effects as a vasodilator are thought to increase circulation within the hoof to help counteract the problems associated with the condition. In theory, that is correct. However, a vet with no understanding of the cause of Navicular Syndrome who does not ensure the cause of the Navicular Syndrome is dealt with first will not likely achieve the desired result with Isoxsuprine since the original cause of poor circulation or the need for enhanced bloodflow to heal the foot is left untreated. It is for this reason that there are many veterinarians, farriers and horse owners who do not believe isoxsuprine to be effective and since there are risks associated with its use, it is therefore rather controversial within the veterinary field. The truth is, it may speed healing of certain horses with Navicular Syndrome - but likely only if the actual cause of Navicular Syndrome has first been addressed and corrected.

Navicular Syndrome causes gradual and progressive lameness, and usually over many years rather than just a few weeks or months, however the horse may not display signs of pain that are obvious, noticed and consistent until Navicular Syndrome has advanced. This horse's death and alot of pain and expense could have been avoided. Due slow onset of Navicular Syndrome, it usually progresses undiagnosed until it's very serious. Knowing the early signs to watch for and treating it early with the method in the ebook above could have saved this horse!

One of the most difficult aspects of treating Navicular Syndrome is misdiagnosis of other problems as Navicular Syndrome, and is one of the main reasons why "Navicular Syndrome" has such a low cure rate. These other problems range from simple chronic low-level laminitis, bacterial and fungal infections, actual fractures in the Navicular bone or other bones, and even wood splinters in the foot ( which when wet may take on gnerally the same density as foot tissue and be missed by low-quality portable radiograph/x-ray equipment). Obviously, even the best Navicular Syndrome treatment won't correct those problems if they were misdiagnosed as Navicular Syndrome!

PDN Block (Palmar Digital Nerve Block ) is often mistakenly the deciding test to deem a horse as having Navicular Pain. If the horse goes sound, there may be a positive diagnosis, since it was once believe the PDN only affects a limited area of the foot. However, recent studies indicate that the Palmar Digital Nerve sensitivity may extend farther toward the toe than once believed, allowing horses with laminitis, fractures or embeded foreign objects in their feet to be misdiagnosed.

In general, the horse with Navicular Syndrome will have pain response to hoof testers applied to the frog. Horses with advanced Navicular Syndrome will have pain response from simple pressure of a thumb or finger pushed between the bulbs of the heel - so much so that you must use caution and keep your face turned away, lest the foot come up off the ground like a rocket to avoid the pain stimulus!

Navicular Disease

Navicular Disease is a degenerative bone disorder affecting the Navicular Bone in the Horse. The key distinction between Navicular Syndrome and a diagnosis of true Navicular Disease is actual pathology; clearly defined visible proof of abnormalities in the Navicular Bone itself by way of x-rays or other devices, such as MRI (Magnetic Resonance Imaging) and which are consistent with past cases of Navicular Disease. No pathology, no disease.   Navicular Disease has been written about for centuries and arguably has affected horses for as long as we have have used them for work.   Joseph Bridge wrote about the first recorded diagnosis of navicular disease in his book entitled "No Foot, No Horse" back in 1752, referring to it as a lameness caused by changes in the "distal sesamoid bone" which is what the Navicular Bone was called back then. Of course the research he did on Navicular Disease would have been post-mortem (after the horse died) since there were no x-rays available back then to see actual changes in the Navicular Bone of a living horse, but these days, we can see actual evidence of deossification - the loss of bone material - with x-rays.

There is almost uniform consensus that Navicular Disease in horses is consistent with osteoporosis in humans. However the cause, as in humans, is still under debate. Modern science believes either calcium deficiency ( not enough calcium ingested ) or deficiency in other minerals which affect the body's use of calcium (such as magnesium, phosphorus, potassium. etc. ) or abnormality in the way the body uses these minerals, such as certain aspects of aging, or perhaps acid rain's effects on soil which releases surplus Aluminium into plants and is then ingested and affects the body's ability to use calcium. This is suspect for humans, horses and other animals, including fish. Since bones act as reserves of minerals important for the body, most notably calcium and phosphorus, when there is defficiency, ( such as in pregnant or aging women ) these minerals are drawn out of the bone and result in deossification or breakdown of the bone. The "recipe" for bone is not unlike that of good bread, where there must be a certain amount of one ingredient for there to be a result that is actually "bread" and not some foul-tasting other thing - where there is not enough of one mineral, "good strong bone" cannot be created, nor maintained. For example, a magnesium deficiency or surplus will affect the way calcium is used in the body.

Bone cells also release a hormone called osteocalcin, which contributes to the regulation of blood sugar (glucose) and fat deposition. Osteocalcin increases both the insulin secretion and sensitivity. Horses fed a high sugar diet, such as "sweet feed" for racing or winter work, have an increased risk of Navicular Disease. Finally, of the most important elements for proper bone maintenance, and one of the key risk factors for bone degeneration, is Torque - slight bending and/or compression of the bone in the way nature intended. It was discovered through testing on astronauts that due abnorbal torquing of their bones ( since zero gravity allowed them to move easily without any strain on their bones, standing, etc ) they experienced a surprising amount of deossification consistent with early osteoporosis common in the elderly ( who also tend to not do much toriquing of their bones) and it was alarming enough to be used as cause to ground an astronaut after only a few missions. The horse with nailed-on metal shoes has a hoof which is prevented from flexing as nature intended and shoes are proven to be a contributing factor to Navicular Disease. Despite it being impractical and possibly inhumane to put an unshod horse to heavy work such as racing or work on miles of pavement, there are very few (if any) reported cases of Navicular Disease (with visible pathology) among horses which have been barefoot all their lives. This may be because barefoot horses are not put to as much work and stress on the bone, or because non-working horses do not receive as much veterinary care as those required for work, or it may be because those not expecting work from a horse are less apt to notice lameness, or it may be due to the way shoes restrict the hoof from torquing the bone, or it may be due to improper trimming of shod horses, or it may be coincidental.

Please note however that some practicing veterinarians will not make a diagnosis of Navicular Disease unless the horse also displays lameness/unsoundness consistent with past trends in Navicular Disease in addition to the pathology. This is rather like your doctor saying to you: "We saw the tumor, did a biopsy and it's malignant ...but if you don't feel like you have cancer, I won't diagnose you with cancer and you don't need any treatment like we'd give to cancer patients." This is because the diagnosis for Navicular Disease is not definitive and absolute. There is no concensus on what constitutes Navicular Disease on x-ray. The original trend adopted for radiographical evidence was "lollipop-shaped invaginations" or "holes which look like lines with a knob on one end" and horses with such anomalies were for many years diagnosed with Navicular Disease. However, recent research on healthy horse cadavers as well as studies on horse fossils over 1,000 years old also showed the same anomalies in over 10% of subjects and no other evidence of bone problems.

Certain cases of Navicular Disease ( depending on their cause and how much damage has been done ) can be treated with some success with Gallium Nitrate to restore and maintain the Navicular Bone.

Caudal Heel Syndrome

Caudal Heel Syndrome is a "catch-all" term used to describe pain in the back (caudal) part of the hoof which has no known specific origin. It is a way of saying "Gee, I don't know what's wrong ...that'll be 500 dollars. The key distinction between Navicular Syndrome, true Navicular Disease and Caudal Heel Syndrome is that with Caudal Heel Syndrome ( IF PROPERLY USED ) there is no pathology and NO ISOLATION of the pain to the Navicular Fulcrum Area. If there was pathology, there would be a definitive diagnosis. If there was proof that the pain was in the Navicular Fulcrum Area, it would be Navicular Syndrome.

Please note however that this term is also often misused by vets who know it is Navicular Syndrome and want to avoid a discussion about Navicular Syndrome, and also often used when the vet is too lazy or too incompetent to do further exploration to ISOLATE & DETERMINE the source of the pain causing unsoundness and to them sounds better for justifying a service fee/bill than "Gee, I don't know." While horse owners want "some" answer to justify the fee, this term would probably be better retired and replaced with the truth: "I am pretty sure what it isn't, and trends indicate that it may be X , Y or Z. The other tests would cost you $XXX and may still not be definitive. So far you've incurred fees of $500. What would you like to do?"