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Navicular in Jumping Horses

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  • Is bone spurs in horses hereditary
  • Class iii x-ray navicular bone horse

 
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    03-12-2011, 01:49 AM
  #11
Trained
Quote:
Originally Posted by bubba13    
And I would not breed her, since there definitely is a genetic component to navicular, or at the very least to conformational attributes that contribute the the eventual development of navicular.
Given my comments above on that factor and also that I agree that 'navicular' is a very ambiguous lable, interested to learn more about the definite genetic component & conformational attributes?
     
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    03-12-2011, 02:08 AM
  #12
Showing
I just wanted to chime in and mention that a diagnosis of navicular changes isn't always a life ending, or even a career ending statement. I am, by no means, an expert on the subject but I do have a bit of experience with it. Many horses, especially so young, that are given time to recuperate and their feet are kept meticulously can go on to lead very productive and competitive lives even with navicular.

My old guy Flash was diagnosed as a 5 year old but with some time off and a good farrier, he came back 100%. He spent many years as a competitive show and team roping horse and ranch horse before being claimed as my step-mom's trail partner (she was a beginner). He finally had to be retired in the fall of '07 at 23 because the arthritis in his shoulders was giving him fits and he was having some minor issues with his navicular. He was still sound for light riding, but we would often spend hours a day horseback over very rough terrain and we felt that work like that would be too rough on him.

I can't tell you why Davis didn't see it. It could have been for any reason, but either way, people make mistakes. It happens and I've learned that it doesn't help to get upset about things that are already said and done. Try to think about what to do now. Get your vet and farrier working together to figure out the best game plan for your mare and if you feel hesitant about what they suggest, don't be afraid to get a second opinion.

Don't worry, it's not the end of the world. Think of it more as a speed bump.
     
    03-12-2011, 02:27 AM
  #13
Banned
Well, I'm no physiologist or equine anatomy expert, but clearly there are some very visible conformations that predispose towards the development of navicular: inherently bad feet, short/upright pasterns, excessive weight on the front end, and such. These are obviously genetic. And beyond the macroscopic scale of such unfortunate inherited deviations, you have to wonder about smaller things that we don't know about....I passed on buying a horse a couple years ago when his X-rays turned up "enlarged vascular channels" in the navicular bone. He was a young guy who had, admittedly, been started earlier than I would have liked, but I don't think he had been ridden into the ground by any stretch of the imagination, either. The consensus of the (lameness expert) vets who viewed his films was that he was a ticking time bomb to end up a cripple within a few years. His conformation was really quite good, and his farrier care had been at least adequate. So something was at play beneath the surface there....

Of course it's not like HYPP or other truly genetic diseases--there's no "navicular gene" or anything. It is, naturally, a very complex and poorly-understood phenomenon. I'm sure that it is most often a combination of nature and nurture elements, and I am equally confident that there are cases of navicular that are 100% inherited from poor breeding (I've heard of stallions who "throw navicular more often than they throw color") as well as cases that are 100% induced by poor care.

As for the mare in question, at six she is still quite young to be showing signs of wear and tear, regardless of how hard she was ridden in the past. Now there are a number of assumptions here. I'm assuming, since the changes are visible on radiographs, that we're looking at true navicular disease as opposed to navicular syndrome here. I believe, but frankly have no readily-available evidence to support, that the former has more of a genetic component than the latter. But I'm guessing we're talking about lollipop lesions/enlarged vascular channels and/or bone spurs/remodeling here--and I'm also assuming that vet #2 is right. Otherwise, all bets are off and this may not even be a navicular horse. But if we are indeed talking about bone deterioration, how much hard riding and terrible shoeing would it take to do that to such a young horse? A helluva lot, I'd say, unless again there was an underlying genetic or conformational issue.
     
    03-12-2011, 06:33 AM
  #14
Trained
Thanks for that Bubba. It's all very interesting to me. I know it has been - and still is, to a large extent - a poorly understood disease and that it has been assumed in the past that it was largely genetic - because they couldn't explain it otherwise. There are indeed still unanswered questions about it(not to mention too many unquestioned answers!) Also as stated, not saying genetics play no part. But current research & evidence is mounting to suggest that it is very much 'nurture' over 'nature' that causes it.

So I am all ears for any evidence for or against. As you are so confident of genetic factors, I'm wondering why it's so obvious to you that problems such as "bad feet, short/upright pasterns, excessive weight on the front end" are necessarily inherant/genetic?

With regard to horses that are 'still quite young to be showing signs of wear and tear', considering that any horse has undeveloped digital cushions until 4-5 years, it seems to me likely that hard working youngsters show 'wear & tear' because they're worked young.

I'm also interested in any evidence to support the assumption that 'ND' as opposed to 'NS' is more likely genetic, as in my understanding ND is likely just a progression of 'NS' type problems. Another question I have with the genetic argument is that if it were so, how do horses recover - and they can - from something that's genetically in built?

So... I'm not professing to know the answers, just one of those difficult types who likes to analyse the whys & wherefores, and it just seems to me there are too many questions and discrepancies to make assumptions about genetics and the likes.
     
    03-12-2011, 08:14 AM
  #15
Banned
Back to the OP's original question, if the horse wasn't showing any clinical signs of lameness when the examined her, UC Davis may have decided that the navicular changes shown on the xray weren't significant.

They became significant when coupled with a horse showing a degree of lameness on that hoof.

Finding of navicular changes on Xrays alone do not have a strong positive correlation to lameness. And a single set of navicular xrays is not particularly useful for diagnosis. Several sets, taken over a period of time to show the the progression of the changes is a much more accurate diagnostic tool.

I frequently advised clients to have them taken on pre-purchase NOT as a diagnostic tool but to have for comparison purposes and as an aid in selling the horse down the road.

The disturbing thing to me is the presence of side bone AND any navicular changes in a 6 year old, combined with a strenous work history. I certainly hope UC Davis commented on those findings in their report, even though the horse presented sound at the time of the exam. That would be a big red flag for me in looking at a performance prospect.

I doubt this horse is going to make it to prelim without a lot of medical intervention. Personally, I wouldn't do it. You already have the evidence that she won't hold up to the necessary training. Besides the ethical issues, this way lies interrupted training schedules, missed competetions, frustration, and frankly, safety issues - I don't want to be worrying about my horse's soundness while jumping a 4' course.

I do think selling her, with full disclosure, to someone who is only going to be doing light riding, or donating her, is the right way to go.

All that said, you have my sympathy. This is a miserable situation. I'm sure you have a lot of money already invested in the horse, and I'm sure you thought you performed due diligence with your vet exam. This is a horrible object lesson that nothing with horses is predictable or certain. Good luck!
     
    03-12-2011, 10:02 AM
  #16
Yearling
Agree with Maura 100%.

As many have said, navicular is not completely understood (but certainly better than some on here would have you believe. I think they may be confusing laminitis with navicular).

Here is where I think the confusion comes in: navicular changes seen on radiographs are not like looking at a broken bone. It is not a yes or no question such as "is the horse navicular or not". "Navicular disease" refers to seeing degenerative changes in the navicular bone. The changes often do not correlate to the degree of lameness. How affected the horse is (ie is he LAME), is what most people use to call a horse "navicular". In other words a horse can have navicular disease but if he is not lame most people don't call him a "navicular horse". Hope that makes sense.

A horse can be very lame/affected and have minimal changes to the bone or could be sound and have dramatic changes. The degree of correlation may also be the reason others have stated that the disease is not well understood.

The bottom line is this: you vetted a horse who was not clinically affected (which is what happened, Davis did not "miss" the changes, there was just no lameness associated so they chalked them up to normal degeneration). Now that you have had this horse in training and the changes in the bone are clearly causing clinical signs AND you have had to inject the hocks the picture has changed. Yes some "navicular horses" remain competitive (by far the exception, not the rule) but the proof is in the pudding. Your horse's prognosis for the future is not good. Showing the clinical signs he now shows while being in training, coupled with radiographic changes, his prognosis is not good to go to the level you want, or even for jumping at all.


Your best bet is to follow Maura's advice and sell with FULL disclosure. You're not ending his career, but you're ending one which will not being long lived or happy for him. Find him a better job and get a horse who will be able to take you where you want to go! Good luck, what an unfortunate set of circumstances. Just goes to show no matter how careful you are, horses are a risky business. I hope you find a good solution for yourself and your guy.
     
    03-12-2011, 11:02 AM
  #17
Banned
Thanks for the additions, Tealamutt.

I have known horses with horrible looking navicular x-rays - lots of "lollipops" or lesions in the bone - to stay sound and competive for years, and I have seen horses with very mild changes on xray to show a full range of clinical signs - postive to hoof testers over the heel, classic navicular posture - parked out, trying to take weight off the heel, nerve blocked out sound, etc.

An xray in absence of other clinical signs just isn't valid diagnostically.
     
    03-12-2011, 03:35 PM
  #18
Banned
Quote:
Originally Posted by loosie    
So I am all ears for any evidence for or against. As you are so confident of genetic factors, I'm wondering why it's so obvious to you that problems such as "bad feet, short/upright pasterns, excessive weight on the front end" are necessarily inherant/genetic?
Short of the extreme "fitting" done by halter horse trainers or corrective action to fix congenital defects such as severely crooked legs (and done at a very young age), is there really any way to change a horse's inborn conformation, especially to any sort of high degree? If conformation were so malleable, it wouldn't be a high consideration for breeding....and we know that that's not the case. Both structural flaws and exemplary conformation breed pretty true.

Quote:
With regard to horses that are 'still quite young to be showing signs of wear and tear', considering that any horse has undeveloped digital cushions until 4-5 years, it seems to me likely that hard working youngsters show 'wear & tear' because they're worked young.
Maybe. I honestly don't know. But I'd still think it would take several years of such abuse to show significant changes, unless they were being ridden so hard that no sensible person would ever treat them that way. This would have to be well beyond normal, accepted training practices, I would think.

Quote:
I'm also interested in any evidence to support the assumption that 'ND' as opposed to 'NS' is more likely genetic, as in my understanding ND is likely just a progression of 'NS' type problems. Another question I have with the genetic argument is that if it were so, how do horses recover - and they can - from something that's genetically in built?
As I said before, I sort of made up the former statement just based on my personal experience and deductive reasoning. I don't know that it's factual; but I don't know that anyone has proven otherwise, either. But if/when horses do recover--some can, some can't--it's nearly always with some sort of therapeutic intervention in the form of specialty shoeing or trimming (either that, or "cheating" by masking pain through drugs or other means). You have to fix the hoof balance, change the way you ride the horse, and hope for the best. Or do things like Isoxsuprine (now very controversial) which increases blood flow and thus promotes healing, or Tildren which aids in bone remodeling by preventing bone breakdown. If the horse has inherently badly shaped feet, you have to "correct" them. And so on.
     
    03-12-2011, 07:31 PM
  #19
Trained
Quote:
Originally Posted by tealamutt    
As many have said, navicular is not completely understood (but certainly better than some on here would have you believe. I think they may be confusing laminitis with navicular).
Good posts Maura & Tealamutt! Agree fully, inc with the above. If you were including me in the 'some on here', it was that I was speaking about the general horse community(& some vets it seems) still being largely in the dark about it, despite researchers such as Dr Bowker for eg. Having brought understanding forward in leaps & bounds, on general hoof health, not just 'navicular'. I recommend people look at & consider his findings. Interesting point about confusing with lami, as it seems that some conventional treatments of NS/D can also lead to lami & ‘rotation’.

Quote:
A horse can be very lame/affected and have minimal changes to the bone or could be sound and have dramatic changes. The degree of correlation may also be the reason others have stated that the disease is not well understood.
Something to ponder; why is it that cadaver specimens studied so commonly show degeneration/changes to P3 & nav. Bones to different degrees, as to be classed as ‘normal’, leaving clinical diagnosis of ‘diseases’ largely down to symptoms? Could it be because sound horses are rarely put down/donated for study?

Quote:
is there really any way to change a horse's inborn conformation, especially to any sort of high degree? If conformation were so malleable, it wouldn't be a high consideration for breeding....and we know that that's not the case. Both structural flaws and exemplary conformation breed pretty true.
Sorry that I’m not better at explaining things. I’m not at all doubting that genetics can of course be a problem. What I’m questioning is the assumption that many ‘flaws’ are ‘obviously’ genetic. For eg. When it’s been shown that environmental factors play such a large part in development and horses on stud farms & conventional establishments are kept, fed, brought up in largely the same manner, could the assumed ‘innate’ conformation not be more to do with that? And I’m not doubting ‘conformation’ can be unchangeable, but that’s not at all necessarily the case either, or as above, necessarily genetic.

Quote:
But I'd still think it would take several years of such abuse to show significant changes, unless they were being ridden so hard that no sensible person would ever treat them that way. This would have to be well beyond normal, accepted training practices, I would think.
That is a much rosier view IMO than what seems to be the case. I think this is greatly underestimating the effects of more ‘normal’ apparently ‘sensible’ management. I think that is partly why conditions such as ‘navicular’ are so prevalent.

Quote:
I don't know that it's factual; but I don't know that anyone has proven otherwise, either.
I don’t know if research has yet ‘proven’ otherwise either & I don’t know how much evidence needs to be collected for it to be considered scientifically ‘proven’. But absence of proof is not proof of absence and that is what I’m trying to get at – that it shouldn’t be assumed it must be one way just because it hasn’t yet been proven otherwise.

Quote:
But if/when horses do recover--some can, some can't--it's nearly always with some sort of therapeutic intervention in the form of specialty shoeing or trimming (either that, or "cheating" by masking pain through drugs or other means)
Conventional ‘intervention’ such as above tends to be purely palliative & I’m not sure that ‘specialty shoeing’ is any less ‘cheating’ than drugs, as it doesn’t do anything to halt the progression & often worsens the mechanics, just (usually temporarily) relieves the symptoms. Therefore that’s not what I’m considering ‘cured’ and IME true recovery is often about absence of conventional ‘therapeutic’ treatments.
     
    03-14-2011, 12:59 AM
  #20
Yearling
Just a quick follow up to you Loosie, I hope you didn't think I was being snotty by saying "some on here..." I didn't mean anyone in particular, have just read some pretty poorly informed yet adamantly stated opinions on this BB in the past. I have a lot of respect/encouragement for those (including yourself) who question conventional treatment and wisdom on feet issues. No feet no horse, yet it is one of the most undereducated topics in equine medicine in veterinary programs. Just didn't want anyone to think I was trying to get jabs in or that I think there is "one way" to approach lameness issues! Bucking the system is how we advance (within reason of course!)
     

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