How much bone is needed in a horse to stay sound?
Do these Thoroughbreds for example not have enough bone:
http://s46.photobucket.com/user/tamara104/media/InReality.jpg.html
http://www.sporthorse-data.com/horse/672869/462/Horse_Bold_Ruler-_3big.jpg
http://www.reines-de-course.com/images/Princequillo%202.jpg
“Bone” is a misnomer - you cannot adequately assess the bone density of a horse from the outside. Unless you’re slicing the bone open to then inspect the porous surface and density, you really can’t tell.
What you can do is gravitate towards a certain amount of “substance”, which most people certainly do.
One of my current TBs (OTTB, SS x Lost Code) has the thinnest little legs you’ve ever seen. Over 70 starts across 11 years of racing. And now he’s 21 and by and large one of the soundest horses I’ve ever known. His legs are absolute iron, yet he’s “slight of frame” “thinboned” “not as much bone as I’d like” per many passing comments on his construction.
IIRC there was an article on bone density in different breeds a few years ago - with Arabs having the thickest density. IIRC, TBs were close runner ups. I’d have to find it the article.
THIS
I also have a uber skinny-legged TB. She looks like a delicate show pony but is as tough as iron both physically and mentally. She is 16 and has never had a lame day in her life, no splints, shin soreness, hoof trouble or tendon issues. Nada. She is now a broodmare and I hope she passes this toughness on to her foals.
Beowulf said it well. You can’t judge bone density from the circumference of a horse’s leg. It is widely believed that bigger bone is more durable than a fine-boned animal, but in real life that isn’t always the case. Some bigger horses hit the ground a lot harder and have soundness issues related to their mass. I have also heard that delicate-looking Arabs have the densest bony column.
To me, I just want the horse to be proportionate. A bigger bodied horse should have more bone than a refined, delicate animal. That doesn’t mean one will be more sound than the other, it should just look like the horse’s parts match.
I’m trying to think of examples where “fine boned” can be a reason for sport horse injury…I’m not coming up with much. In racing, bone density is a bigger deal because speed adds a lot of force. Race horses suffer from more bone injury than sport horses. When’s the last time a jumper or eventer bucked his shins? Or had a condylar fracture? Those are basically unheard of in the sport world. Most of our horses’ injuries are joint-related or soft tissue, not really relevant to the width of the cannon bone.
I would maybe consider the middle horse a little light on bone for his body type-- but I agree that it isn’t necessarily predictive of long term soundness. I had a TB mare by Mehmet as a kid whose legs were so narrow she couldn’t wear off the rack jumping boots-- but she never took a lame step in the eight years I had her.
The other thing to consider is the age of the horse, and the appropriate work asked of it. Now that we know more about bone /growth plates, we can start to identify when the “slight of bone” 2 y/o is really just growing and not filled out completely.
Lots of mature TBs have the same bone circumference of the horses Elles posted - but because they are seen at mass by the public at a very young age (usually under 4) they’re perceived to be fine boned. It’s amazing how much they fill out in their fifth and sixth year to the point where it looks as if they are a different horse.
Horses with !ittle bone often have small feet. Is there a link to navicular disease because of this?
In my experience itit’s the ones with lots of bone and small feet that are most prone to navicular.
[QUOTE=beowulf;8358255]
The other thing to consider is the age of the horse, and the appropriate work asked of it. Now that we know more about bone /growth plates, we can start to identify when the “slight of bone” 2 y/o is really just growing and not filled out completely.
Lots of mature TBs have the same bone circumference of the horses Elles posted - but because they are seen at mass by the public at a very young age (usually under 4) they’re perceived to be fine boned. It’s amazing how much they fill out in their fifth and sixth year to the point where it looks as if they are a different horse.[/QUOTE]
This is a great point. At a FEH seminar, my yearling TB received a few comments that he didn’t have enough bone. Compared to the ISH and WBs, he certainly did appear quite light boned. However, for a TB of his age, he was normal.
He’s not going to be a big horse and will probably end up in the 16h-16.1 range. As a late 2 y.o, almost 15.3, he’s starting to fill out and so is his bone. By the time he’s done growing, I think he will look like any average TB as far as bone size. You won’t be confusing him for an Irish horse, but he won’t look like a delicate flower either. For his size and type, his amount of substance is adequate and continues to develop.
I have a TB mare with very light legs, but she raced 65 times and came off the track “with the legs of unraced five yo” per the vet who did her PPE.
[QUOTE=Highflyer;8358274]
In my experience itit’s the ones with lots of bone and small feet that are most prone to navicular.[/QUOTE]
I was going to say the same.
And thinking further on this, I cannot recall in recent memory a horse that had issues because he was fine boned… However, I can recall many times several heavy thickset horses (with broad bone circumference) that had early endings to their career because of side bone, ring bone, navicular, and other bone-related maladies.
Not too long ago, the woman whose horse I took care of for several years, had to retire her big PerchxTB… he was 18h and the size of a trolley car… and has been unsound for years because, per the vet, his construction is too heavy for his body.
‘enough BONE’ is nothing but wishful thinking on the part of humans.
Strong/dense fine-grained bone is what is desired, and has nothing to do with any external visual cues.
You can only somewhat predict bone quality from ancestor/siblings/family performance over a long time.
If they remain sound throughout long, useful lives their bone is good, no matter what they ‘look’ like. And in my opinion, that includes ‘accidents’, too. Some horses will become recoverably lame from a misstep, others permanently unridable, a few are sound by the next morning. This is significant.
Animals that do not require or have not had surgical intervention to remain sound, correct problems or eliminate blemishes such as OCD lesions -and are sound in strenuous work- are better breeding prospects than their peers.
None of this has anything to do with ‘marketing’ of horses. There you need to meet the prejudices of your buyer: horse needs certain angles or straightness of leg, amount of cannon circumference, arch of neck, prettiness of head, etc.
Until they are at upper level performance, when they will sell if they can do the job.
Far more upper level sport horses are sidelined by soft tissue injuries than bone related ones. The integrity of the soft tissue is very hard to predict or assess beforehand. It must have a genetic component as there are several lines that never seem to hold up in this regard.
What I’ve been finding interesting most recently is that it seems many injuries that present in the lower limbs are actually the result of poor spinal alignment and that this accounts for far more unsoundness than was previously thought. So I think that as others mentioned above, the overall balance and picture of the horse may tell you more about its longevity than the stoutness of its limbs.
I have seen on this very forum (and other places) statements like, “the Damascus line brings soundness.” Yet horses with him close up are some of the finest-boned horses I have ever seen in my life.
Regarding the three influential sires the OP posted, when I look at all three of them, I think they they all appear to be balanced with the appropriate amount of bone for their breed and body type. Of course, as others have said, you can’t see bone density with your eyes. One way to increase speed is to reduce the size of the frame-- one shouldn’t want their thoroughbreds with the same amount of bone as draft horses or even warmbloods.
I find that very interesting! What kind of lower limb injuries are you talking about please?
[QUOTE=winter;8358484]
What I’ve been finding interesting most recently is that it seems many injuries that present in the lower limbs are actually the result of poor spinal alignment and that this accounts for far more unsoundness than was previously thought. So I think that as others mentioned above, the overall balance and picture of the horse may tell you more about its longevity than the stoutness of its limbs.[/QUOTE]
we have an 11yo TB, raced until he was 7 and retired sound without even a windpuff.
he has tiny stick thin legs and tiny 13hh pony feet (he’s 15.1hh) but he is the toughest horse i know, never sick or sorry and definitely never lame.
hes competing 3rd level dressage barefoot and schooling PSG…and hacks too 
i think its impossible to judge quality of bone/toughness from leg circumference…as long as the legs match the frame…what worries me is beefy bodies on tiny legs.
Does this also have to do with it?
http://www.scienceofmotion.com/documents/thorse_training_philosophy.html
[QUOTE=winter;8358484]
Far more upper level sport horses are sidelined by soft tissue injuries than bone related ones. The integrity of the soft tissue is very hard to predict or assess beforehand. It must have a genetic component as there are several lines that never seem to hold up in this regard.
What I’ve been finding interesting most recently is that it seems many injuries that present in the lower limbs are actually the result of poor spinal alignment and that this accounts for far more unsoundness than was previously thought. So I think that as others mentioned above, the overall balance and picture of the horse may tell you more about its longevity than the stoutness of its limbs.[/QUOTE]
[QUOTE=winter;8358484]
Far more upper level sport horses are sidelined by soft tissue injuries than bone related ones. The integrity of the soft tissue is very hard to predict or assess beforehand. It must have a genetic component as there are several lines that never seem to hold up in this regard.
What I’ve been finding interesting most recently is that it seems many injuries that present in the lower limbs are actually the result of poor spinal alignment and that this accounts for far more unsoundness than was previously thought. So I think that as others mentioned above, the overall balance and picture of the horse may tell you more about its longevity than the stoutness of its limbs.[/QUOTE]
I’d be interested to read up on the material you’ve read.
IMHO, horses are poorly designed. It’s not surprising to me they suffer soft tissue injuries. The thing is, riding places incredible amounts of strain on their bodies. I’m honestly more surprised when they’re sound their entire lives.
[QUOTE=Highflyer;8358274]
In my experience itit’s the ones with lots of bone and small feet that are most prone to navicular.[/QUOTE]
IME it’s more about the weight of the horse vs his feet, than his overall bone. Look at the stereotypical halter-bred QH - large musculature, heavy body, but thin lower legs (forearms and gaskins are often overly-muscled) and small feet. Definitely not lots of bone there.
Small-diameter legs means either less room for the ligaments and tendons, or smaller ligaments and tendons, so all else equal, finer-boned in relation to their body is not good. But if it’s a finer-boned horse all around, it’s all proportional.
IMHO, the bone issues of the racing stock has more to do with their work, than their structure. Too much speed work too early makes for bucked shins because the stress is too much for how fast the remodeling is taking place. There are a few studies out there which showed that a more careful approach to getting speed work done greatly reduced bucked shin issues. Same with people - run too far too soon and you will have really sore shins, even to the point of causing some stress fractures (not even taking into account the poor running form most people have).
As mentioned, diameter/circumference isn’t a good indicator of density, let alone density as it relates to horse’s weight. Drafts have a relatively light bone density, compared to their weight, despite their greatly increased leg circumference - nothing about their breeding necessitated dense bones, just the ability to pull
