What Causes Navicular??

Elsbells

Elsbells

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With all the navicular posts on here recently and the following disagreements re. the cure, I have been left wondering if some-one could tell me about the basics of this horrible and often fatal disease?

I'm sure I'n not the only one whose head is left spinning;)

For one, how it is caused in the first place? How can it be avoided? How do you know your horse has it? What is the best long term management advce you can offer, which will give my horse the best chance of never suffering navicular in the first place?

There's more...

Do certain breeds suffer it more? Are there certain disciiplins that seem to create the navicular horse? And, is it more previlent now than it was say 30 years ago?
Just about everything really.;)
 
Interesting post. I had a flat, sensitive footed tb who chipped his navicular bone when he was only 6. His other foot was fine and another weird thing was that the foot with the chipped nav bone was the better foot (his right hoof rarely cracked unlike the left one and in general always looked better). I dont think it is preventable as horses are always on there feet so if its going to happen its going to happen ... well thats my thinking anyway :p But i suppose riding on a proper surface and not hammering the roads would be classed as preventative measures?? Wouldnt say its cure-able either, you can make them as comfortable as possible but it wil always be there so not cured ... but again just imo :D
 
Basically, the current thinking is that Navicular problems in the horse are caused either by compression or tension within the hoof.

It normally shows up in horses which have been shod all their lives at around 11 yrs of age.

Because shoeing causes a malformation of the hoof by the atrophy of the digital cushion and frog. We know that shoeing restricts blood flow to the hoof, the navicular bone, in response to overall decreased blood supply, would start to degenerate.

Toe-first landing, usually seen as a consequence of navicular disease, may actually be a cause or at least a contributing factor to the onset of tendon inflammation and bone modifications.

Toe-first landing is often caused by frog and heel overtrimming, long toes, and shoeing.

Conformational defects may contribute to Navicular Syndrome, especially defects that promote concussion. These include upright pasterns, small feet, narrow and upright feet, and long toes with low heels commonly seen in Thoroughbreds.

It is possible that standing can increase the chance of navicular such as a horse that spends most of the day in a stable with little turnout, as seen in racehorses and some show horses. This is because blood flow to the hoof decreases when the horse is not in motion. The horse is also constantly applying pressure to the navicular bones which is intermittent as the horse moves.

Although navicular disease is fairly common in the modern day domesticated horse, it is virtually non-existent in wild horse populations.
 
I know of navicular spectrum lameness in three barefoot horses. The common factor was that each of them had grown a ring of hoof like a shoe, and their frogs were no longer ground bearing. Each was resolved by getting the frog ground-bearing again (one is still in rehab).

At the same time, for shod horses with the syndrome, barefoot, bringing the frog back into use, is proving to be at least 4 times more effective in bringing navicular horses back into full work than remedial shoeing and medication. I therefore conclude that most navicular is probably caused either by shoeing the shod horse or allowing the unshod horse to grow itself a "shoe" - ie it is caused by peripheral loading of the hoof, which causes the back third of the foot (called the caudal hoof by vets) to atrophy, which causes pain in the back half of the foot, which causes the horse to land toe first to evade pain, which then damages the tendons and ligaments inside the foot making the horse lame.

Colateral ligament damage, if not identified by MRI, is often diagnosed as navicular syndrome, and that appears to be caused by the horse being given a foot which does not match the side-to-side loading which it needs. On rockleyfarm.blogspot.com you can see photos of horses which arrive lame with collateral ligement damage who then grow a foot whose side walls are at drastically different angles than the way they grew in a shoe, and then they come sound. For some horses, farriery forces a "symmetrical" appearance on the foot at the horse's peril, because it does not match the loading of the bones in the leg. A barefoot horse may grow a wonky looking foot, if it was lame in shoes and sound with the wonky foot, that's what it needs.

The state of the navicular bone itself is a VERY poor predictor of lameness and I reckon personally that it's a complete red herring most of the time. If 100 sound horses were xrayed about half of them would have bone changes. On the other hand, research has shown that if you MRI or dissect (dead) lame horses there is almost always soft tissue damage to the deep digital flexor tendon or the collateral ligaments or both. In spite of this a leading veterinary hospital recently gave friends of mine a VERY poor prognosis of their horse ever returning to work, on the basis of the damage to his navicular bones. He's been in barefoot rehab one month and is currently in work walk, trot and canter sound. It makes me want to scream, or cry, that what should be the most expert of vets are still giving owners such rubbish advice when the research is out there.
 
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My horse has just recently been diagnosed with ringbone in the coffin joints. I've been thinking about asking my vet and farrier if removing his shoes would help. Not sure what answer they will give. Do you think it would help him in the same way it helps horses with navicular? I'm told by my farrier he has good feet, but one of my concerns is he's a heavy cob and I'm a happy hacker and do a lot of road work, I am prepared to buy boots if it helps. It's early days yet with his treatment, and he is still slightly lame in trot. But I want to do whatever I can to help him.
 
elsbells said:
How do you know your horse has it?
Click to expand...

A toe first landing is a predictor, because that action is likely to be causing problems to the ddft.


elsbells said:
What is the best long term management advce you can offer, which will give my horse the best chance of never suffering navicular in the first place?
Click to expand...


Make sure your horse is weight bearing on his frogs. You should not be able to slide a credit card under your horse's frog when it is stood on a flat hard surface. This is extremely difficult to achieve in shoes.

If you have to shoe, give the horse 3 months a year without them on, like we used to do in the old days. I believe that this change in management has resulted in increased rates of navicular.
 
Pale Rider said:
It normally shows up in horses which have been shod all their lives at around 11 yrs of age.
Click to expand...

In ex flat racing TB's which have been shod at 18 months it is common at 4 and 5 and in other horses it is very often found from 7 years old. I have had three horses with it, one 5 year old ex racer, one 5 year old TBx and one 7 year old IDx.
 
cptrayes said:
I know of navicular spectrum lameness in three barefoot horses. The common factor was that each of them had grown a ring of hoof like a shoe, and their frogs were no longer ground bearing. Each was resolved by getting the frog ground-bearing again (one is still in rehab).

At the same time, for shod horses with the syndrome, barefoot, bringing the frog back into use, is proving to be at least 4 times more effective in bringing navicular horses back into full work than remedial shoeing and medication. I therefore conclude that most navicular is probably caused either by shoeing the shod horse or allowing the unshod horse to grow itself a "shoe" - ie it is caused by peripheral loading of the hoof, which causes the back third of the foot (called the caudal hoof by vets) to atrophy, which causes pain in the back half of the foot, which causes the horse to land toe first to evade pain, which then damages the tendons and ligaments inside the foot making the horse lame.

Colateral ligament damage, if not identified by MRI, is often diagnosed as navicular syndrome, and that appears to be caused by the horse being given a foot which does not match the side-to-side loading which it needs. On rockleyfarm.blogspot.com you can see photos of horses which arrive lame with collateral ligement damage who then grow a foot whose side walls are at drastically different angles than the way they grew in a shoe, and then they come sound. For some horses, farriery forces a "symmetrical" appearance on the foot at the horse's peril, because it does not match the loading of the bones in the leg. A barefoot horse may grow a wonky looking foot, if it was lame in shoes and sound with the wonky foot, that's what it needs.

The state of the navicular bone itself is a VERY poor predictor of lameness and I reckon personally that it's a complete red herring most of the time. If 100 sound horses were xrayed about half of them would have bone changes. On the other hand, research has shown that if you MRI or dissect (dead) lame horses there is almost always soft tissue damage to the deep digital flexor tendon or the collateral ligaments or both. In spite of this a leading veterinary hospital recently gave friends of mine a VERY poor prognosis of their horse ever returning to work, on the basis of the damage to his navicular bones. He's been in barefoot rehab one month and is currently in work walk, trot and canter sound. It makes me want to scream, or cry, that what should be the most expert of vets are still giving owners such rubbish advice when the research is out there.
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I tend to agree with the conclusions that you have outlined here.

It is important that concussion on the hoof be dealt with by the digital cushion, and blood flow to the hoof be maintained at an optiimum by the mechanical action on the frog.

The damage to frog and ditgital cushion caused by the shoe or peripheral loading of the hoof by poor trimming, gives rise to the toe first landing of the hoof which causes exessive tension placed on the ligaments that support the navicular bone. Excess tension can also cause extra bone growth where the ligaments attach to the navicular bone. If tension is extreme, the ligaments may actually tear. The DDF tendon may become damaged by the constant rubbing against the navicular bone, due to the friction between the navicular bone and the DDF tendon.

Therefore I would agree with your supposition that soft tissue damage is probably the cause of the lameness.
 
I just wanted to say that this is an interesting thread. I have long been of the opinion that poor farriery can cause or maybe 'bring on' navicular. If heels are contracted and not weight bearing as they should be then I really believe herein lies a huge pointer and problem.
My hubby is often in the position where he has to 'widen' the hoof to it's natural size because it has previously been shod far too tight and small by a previous farrier; this means these horses lose shoes during the transition period as he shoes wide to enable the foot to widen. Tellingly many owners choose barefoot once navicular is diagnosed.
 
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[/quote]Make sure your horse is weight bearing on his frogs. You should not be able to slide a credit card under your horse's frog when it is stood on a flat hard surface. This is extremely difficult to achieve in shoes.

If you have to shoe, give the horse 3 months a year without them on, like we used to do in the old days. I believe that this change in management has resulted in increased rates of navicular.[/QUOTE]

This is reasuring cptrays, thank you and just what I have planned this year.

Why do farriers cut the frog then? I have asked my farrier and he just says that is how he shoes??
 
YasandCrystal said:
I just wanted to say that this is an interesting thread. I have long been of the opinion that poor farriery can cause or maybe 'bring on' navicular. If heels are contracted and not weight bearing as they should be then I really believe herein lies a huge pointer and problem.
My hubby is often in the position where he has to 'widen' the hoof to it's natural size because it has previously been shod far too tight and small by a previous farrier; this means these horses lose shoes during the transition period as he shoes wide to enable the foot to widen. Tellingly many owners choose barefoot once navicular is diagnosed.
Click to expand...

This for me is a difficult one, in most fully transitioned barefoot horses hooves are smaller than they are when shod, caused by the hoof capsule tightening up. Look at the first half inch of growth from the coronary band, which gives an indication of where the hoof wants to grow. The very presence of the shoe restricts the natural expansion and contraction of the hoof which supports increased blood flow. Barefoot, is in my opinion the only way to reverse the damage caused to the hoof which causes the lameness.
 
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