Biomechanics, Inbreeding & Breakdowns

[Patuxet]

Native Dancer has been the topic of recent blog posts from Frank Mitchell and John P. Sparkman, two of the best living bloodstock writers in this country.

http://pedigreecurmudgeon.blogspot.com/

http://fmitchell07.wordpress.com/2009/12/11/native-dancer-reshaped-the-breed/

Be sure to read the comments their posts stimulated.

Here's a quote from Mitchell which particularly pertains to this discussion:

The transitional aptitudes of the classic-quality miler who excelled at 10 furlongs was the beau ideal of the 1940s through the 1960s, when Nasrullah and his son Bold Ruler were the most important influences on American breeding, ably assisted by Princequillo and his great son Round Table.

These horses were beautifully balanced in their physical quality and in their biomechanical properties, as well. And if they had a degree of mechanical imbalance about them, it tended to be toward stride length. They were good-bodied, medium-sized to big horses with speed and stamina. A breeder, however, would never mistake a Nasrullah for a Quarter Horse, which is the archetype of the power profile in mechanical development.

On the other hand, Native Dancer possessed those power characteristics of the Quarter Horse allied with size and scope that allowed him to excel at distances from five furlongs to a mile and a half. Native Dancer, in terms of his physical traits, was out of synch with much of the breed by having so much more power than the typical strains of Thoroughbred used by major breeders.
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"He is pure air and fire and the dull elements of earth and water never appear in him; he is indeed a horse ..." Wm. Shakespeare - Henry V

[Matchemforever]

Patuex,

Thank you for those links. I found this nosing around the first one:

http://www.opencomputing.ca/ormonde/ftp/Corruption%20of%20a%20legacy.pdf

Really made me think that perhaps we do have it backwards in thinking that the Europeon horses are sounder. This article makes the point that it may have been the introduction of the Europeon blood on American horses that set this country up for losing durability and soundness. In Europe, they raced on grass and ran races differently than here in the states.

Very, very interesting take on things and seems to make some sense.


I've often wondered if Selene was one of the pathways for the upright and short pasterns, whether she had them herself or not.

Her sire:

http://www.tbheritage.com/Portraits/Chaucer.html

His dam:

http://www.tbheritage.com/Portraits/CanterburyPilgrim.html
and take a look at her sire, Tristan, on the same page.

Obviously, there were some successful race horses and not necessarily unsound ones but it kind of supports the idea that perhaps they could get away with that in Europe, but once those underpinnings were crossed on the Domino underpinnings, plus added body size, and what hardly caused a problem in Europe becomes a problem in America?


Edited to add that Nessa had pointed out previously that in Europe, because of racing conditions, they could get away with lighter bone perhaps.

[Shammy Davis]

http://www.ker.com/library/advances/147.pdf

[Shammy Davis]

http://www.gaitedhorses.net/Articles/OG/OriginsOfGait.shtml

[Shammy Davis]

http://www.ker.com/library/Equinews/v6n4/v6n410.pdf

[Matchemforever]

I forgot what I was looking for when I found this:

http://horsegears.com/index.html

Don't know how "scientific" it really is and I do wish the site had more examples with measurements, etc. In terms of biomechanics, I thought this might give another perspective.

Short pasterns, for example, are equated with speed horses. But whether that is a generality of that type of horse, or an inherited trait that just happens to be there, ?

I'm still trying to figure out how I'm looking at pictures of Secretariat wrong when they describe him as having long cannon bones. I think short cannon bones are shorter than the upper portions of the leg and I don't know what would define their definition of "short."

Still pondering also over the idea that stayers have longer cannon bones because I thought that predisposed a horse to higher action and that that was not usually a trait of horses that go a distance.

(Which brings in the thought that Man O' War was described as having high action, "bounding" strides, but certainly capable of distance and another horse I don't think of as having long cannon bones in relation to the rest of his leg. Maybe there is some place where the site describes what they mean by that but haven't found it yet by skimming)


Another site of interest for the pictures provided, since most of them are of the same type, after the horse retired:

http://www.thoroughbredtimes.com/stallion-directory/media/resources/classic-gallery.pdf

Right up front are pictures of Alibhai, Buckpasser, and War Admiral side by side. My first thought was why everyone was so enamored of Buckpasser's conformation. Granted, maybe the angle of the shot does this but he looks to be very upright in his pasterns compared to the other two, who to me don't look to have long pasterns but do have angulation. Buckpasser, in this photo, also looks butt-high.

For comparison, I looked up the photo of Fair Play, who I always kind of thought was on the shorter side in the pasterns, but who does have angulation nevertheless with adequate bone.

Looking at some of the more modern alleged problem sires, at this site and elsewhere, I get the impression that the pasterns are less substantial-like suddenly narrowing the stream at that point. Maybe that's just another illusion of the photos?

[Shammy Davis]

I was watching TVG. They did a short clip on Sunland and the Sunland Championship. MIND THAT BIRD was honored by leading the post parade. I'm a retired farrier and I noticed that he is toed-out. I could be wrong, but I don't think so.

MTB is an interesting sample of a horse who has very efficient movement and probably very little corrective work was done on him. Remedial trimming or shoeing is unwise because the problem (deviation) actually lies in the fetlock joint.

As I recall GRINDSTONE is his sire. SUMMER BIRD is from the same crop. Wonder what his hoof conformation is?

Here is a general link: http://www.horseshoes.com/anatomy/anatomy.htm

[dublino]

[Shammy Davis]

dublino: This was started as a serious thread.

The individuals who post to it are serious about the subject as I try to be.

If you want to enjoy your dislike for me take your sniping and childish behavior back to the non-horse section of this website where your talents can be better recognized and appreciated. Otherwise I know the other participants on this thread will appreciate you only posting to the subject if you have questions or anything of value to offer.

[dublino]

As I said cry Heretic.

[Shammy Davis]

Xfactor Fan: It is apparent that the lively banter from another non-TB section of this website has now infected this thread. For that, I would like to apologize to you and the other participants of this thread. I really don't know what to do concerning dublino's posts so I will refrain from posting to allow civil behavior to return to this subject. Once again, I offer my sincerest apologies.

[xfactor fan]

Shammy, please continue posting to this thread. Just ignore dublino.

Loved the biomechanics website. They have some very interesting ideas. Now if we could find the genetic basis for the different body types so that breeders had a better chance of getting a sound functional race horse, life would be good.

Matchemforever, I don't equate short cannon bones with unsoundness. Fingers didn't keep up with the thoughts. What I was trying to get at, is there may be three ways to lighten the weight of the lower leg and increase speed.

Shorten the cannon bone
Decrease bone density
Decrease bone size.

Thanks to some other information posted, adding shortening the pasterns--and most likely decresing hoof size will also lighten the lower part of the leg and increase speed.

The functional trade off for breeding for speed, may be a loss of soundness due to mechanical reasons.

Without mapping the genes involved in leg formation, it is impossible to state that all these factors are under the control of different genes, but that's the way I'd bet.

So in the TB gene pool, there will be horses that have all possible combination, short cannon bones, long cannon bones, good bone density, bad bone density, decreased bone size, robust bone size. Throw hoof size, and length of pasterns into the mix and there's an amazing range of possible leg shapes.

Now to prove this theory, someone would have to look at a whole lot of legs, and track soundness/breakdowns and try to match them up with phenotypes. Would be a very interesting statistical study.

[Matchemforever]

Shammy,

You are correct about Mine That Bird. His trainer has stated that he is "not quite correct" in front. I think that, coupled with his attitude as a youngster, made the decision to geld him a bit easier.

My take is, you don't try to correct that conformation fault when they are grown. If you can do anything-and I have doubts about that-you have to intervene when they are young. You shoe them as they are or you WILL make them lame. But that's my two-bit opinion.

[Shammy Davis]

Matchemforever posted:

[Matchemforever]

xfactor fan said:

"
Thanks to some other information posted, adding shortening the pasterns--and most likely decresing hoof size will also lighten the lower part of the leg and increase speed."


Maybe just take this one thought and observation. Are the better race horses medium to short in the pasterns and if so, why would that be an advantage?

Do speed horses have shorter pasterns and if so, why? What advantage biomechnically would this give them? Doe this quicken up the stride even if that stride is long?

Whether the short pasterns are sound may have to do with how much bone density is there and how steep they are. I've always read that short pasterns are predisposed to problems anyway. Add upright and that just compounds the problem. But for some reason, upright and short seems to have been there far more often then you'd think.

Is there any biomechanical advantage at all to the following with regards to speed (Not factoring in bone density):

short pasterns
short, upright pasterns
just upright pasterns, regardless of length


When you get to a horse like Ruffian, I always thought those, to me, long pasterns were just trouble waiting for opportunity, so she's on the other end of this and does not come under an "advantage" for shorter pasterns. Obviously, shorter does not always equate to advantage but if they are there in horses that ran well and bred the trait on, something was being selected for.

When you look at the TB Heritage site and begin looking at the legs, photo angles aside, seems many of the horses had upright kinds of pasterns. Perhaps on turf this didn't hurt them.

Then getting back to another thread on origins of the TB, where I think we kind of dispelled the idea that the Arabian was the predominant ancestor, was there an ancestor that tended to have upright pasterns? Where did that come from? Many of the very early horses in history were gaited- do gaited horses tend to long pasterns?


Edit:
One of the links provided by Shammy got into post-legged horses and that this might be an advantage for racing. But does a post-legged horse tend to throw more weight on the front end? Is there something about the lack of angulation in the hind end that would cause excessive weight bearing on the front? (Not that racing horses don't weight the front end more anyway)

Thinking out loud here...would a post-legged horse spend less time with those hind legs on the ground, in a weight bearing phase, than a horse with angulation? The difference would be small, but over time, distance and speed, could add up to quite a bit more punishment for the front legs.

Does a horse with long, low strides in front, spend more time with those front legs in weight bearing phase than a horse with higher front end action?

Sorry, it's Sunday and the brain is taking a day off too....