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vineyridge
Mar. 30, 2011, 01:19 PM
Bone density scans are very, very common in humans. Are they, or should they be done on competition (UL aimed) event horses and racehorses?

I was wondering if old OCD lesions impacted the structural strength of bones as well.

deltawave
Mar. 30, 2011, 01:29 PM
Bone density studies are virtually never done on young, active, athletic humans, though, unless they are on long-term, high dose steroids or are known to have metabolic problems or anorexia.

As far as I'm aware there does not exist "osteoporosis" in horses, and the type of fractures they get are usually from intense trauma/injury and not the spontaneous "bones falling apart" variety.

Having said that, if one thinks about using this sort of test, first there would need to be norms and standards, and then there would need to actually be some sort of recommendations to either treat or retire animals deemed to be "abnormal" or "at risk". That would require heaps and piles of data, with not much of a chance for a good solution. Would a screening test on young horses weed the "at risk" ones out? What would happen to those horses?

I guess if the data were there, it could be considered an adjunct to a PPE, but since the current test is primarily used to document abnormal bone pathology in elderly individuals, rather than predict risk of fracture in young athletes, it would take a LOT of information to serve as a useful database. And a LOT of money, and a LOT of equipment, and a LOT of radiation . . . :)

And OCD is primarily a cartilage/end plate sort of lesion, isn't it? That certainly would impact the integrity of the local area, but not sure how that would impact the shaft of the bone or the structure of the bone itself beyond the immediate location of the lesion.

RAyers
Mar. 30, 2011, 01:30 PM
Bone density scans are crap. They give relatively little viable data other than a clinical likelihood of fracture based on demographics. We published a paper in 1996 describing the multiple failings of bone density scans as a measure of bone material properties and actual bone structure. We used DEXA as part of a osteoporosis study flown on the Space Shuttle. When compared to the data we took by actually breaking the bones and looking at the structure, we found no real validity in DEXA or other bone density scan.

I am against bone density scans even in people. They take a 3 dimensional structure and render it into a 2D space that many times doctors do not accurately understand. Even the software is suspect as the statistics are based on an assumed standard of density based on intensity. Again, we find in reality there is no such even correlation.

As for an OCD lesion, it is not an actual indicator of potential fracture/failure in bone as one may think of a crack in steel. Bone is an anisotropic heterogenous composite that has a very complex failure/fracture mechanism that is still not well understood or modeled. At the structural level, the shape has more influence than the make-up of the bone when predicting fracture.

Reed

riderboy
Mar. 30, 2011, 01:30 PM
I'm not sure what you do with the information. Plain films should be able to show significant lytic lesions in bone. I mean, would you retire an UL horse based on that information, which can be interpreted in different ways? Maybe there's a radiologist out there who can pitch in here. I just don't know.

riderboy
Mar. 30, 2011, 01:33 PM
Hey! You guys must have been typing as I was typing. I think that they have answered the question!

CANTEREOIN
Mar. 30, 2011, 01:42 PM
Deltawave and Rayers...

I was about to launch into my own rant about the overuse of major diagnostics and having information with not comparable studies/statistics to determine whether or not the information found was useful or conclusive one way or another...

Thanks

deltawave
Mar. 30, 2011, 02:31 PM
Still I'd bet you'd find people willing to pay to have it done, and people willing to make a buck off it. :no:


Bone is an anisotropic heterogenous composite

Reed, you're such a weenie. :p

RAyers
Mar. 30, 2011, 02:38 PM
Reed, you're such a weenie. :p

But an anisotropic heterogenous composite weenie.

By the way, vineyridge, this is a valid consideration and so don't take my critique as a personal comment.

sisu27
Mar. 30, 2011, 03:06 PM
Dense population of smart folk on this thread....

I'm about to change that:D

I read something recently that was someones attempt to dispel the "large bone is better" theory.

In short they proposed that the larger boned horses were actually more at risk (for fracture) than the smaller boned animals as they had more porous bones. So the actual amount of bone was the same but just took up more space in the larger boned animals.

As the owner of a large boned thbd (10" cannons IIRC) I wasn't a big fan of this concept.

Thoughts?

RAyers
Mar. 30, 2011, 03:34 PM
Dense population of smart folk on this thread....

I'm about to change that:D

I read something recently that was someones attempt to dispel the "large bone is better" theory.

In short they proposed that the larger boned horses were actually more at risk (for fracture) than the smaller boned animals as they had more porous bones. So the actual amount of bone was the same but just took up more space in the larger boned animals.

As the owner of a large boned thbd (10" cannons IIRC) I wasn't a big fan of this concept.

Thoughts?


The idea of "big bone" is more an idea of the old horseman's philosophy concerning lameness. The theory has already been dispelled at the scientific level when it comes to fracture. It is WHERE the bone is in 3D space and not necessarily how MUCH bone there is. The navicular bone is a good example. Many times there may appear to be large holes but the bone itself is as strong as one that has no holes.

Now a "big boned" animal may be more likely to fracture due to a increased structural stiffness (can't bend as well). However, I am more aligned with the idea a bigger bone animal has a larger muscle and tendon mass so that when the ligament feedback loop fails as the animal gets fatigued, the muscle will literally pull the bone and/or tendon apart. This has been studied fairly extensively in football players and other large athletes.

fooler
Mar. 30, 2011, 03:41 PM
I am with sisu27 :D

Although the information is dated. . . Equus magazine, when first published, followed a young Arabian horse from birth to around 3-4 years.
They studied and gathered data about bone density and the effects of different types of exercise at different ages.

IIRC - their findings 'seemed' to debunk the large bone size = strong bones. Instead they encouraged slow steady work, including ponying, to encourage bone density - sorry can't remember the proper termnology.

Peregrine Farm
Mar. 30, 2011, 03:44 PM
Not an expert here, either, but Equus Magazine had an interesting article in October 2007 called "Size Matters" that IIRC addressed the bone density question and the increase in the average size of horses over the last few hundred years. I did a quick search and was unable to find a link to the article, but perhaps someone can find it.

What I remember is a comment that for a draft horse to have the same relative amount of "bone" as a primitive horse, like the Prezwalski's Horse, its legs would be as big around as telephone poles, or something like that. The point was that as horses get bigger, there is an increased chance of soundness issues (no news there), but at the same time one of the vets who contributed to the article admitted that he rode a 17 hh warmblood and didn't think twice about it.

RAyers
Mar. 30, 2011, 04:15 PM
Peregrine, I agree with your sentiments but here is a point of misconception/misunderstanding I would like bring up, bone density DOES NOT EQUATE to size of bone. This is why the common literature can be very misleading concerning the ideas of medicine. This is similar to the ideas discussed in the "What is the best term for 'equine heart attack'?" thread. Just because a horse or human gets larger dose not mean they have denser bones. Hence why bone density scans are crap.

Again, it goes to where the bone is in space that dictates its load bearing capacity. I can assure you that studies have shown that the bone in elephants are roughly the same density as what is humans. I remember an study done in the 80s that looked at the vertebrae in whale, antelope, and some other animal and there was very little difference in the bone itself. The difference was in where the bone was organized.



...addressed the bone density question and the increase in the average size of horses over the last few hundred years....

What I remember is a comment that for a draft horse to have the same relative amount of "bone" as a primitive horse, like the Prezwalski's Horse, its legs would be as big around as telephone poles, or something like that. The point was that as horses get bigger, there is an increased chance of soundness issues (no news there), but at the same time one of the vets who contributed to the article admitted that he rode a 17 hh warmblood and didn't think twice about it.

Peregrine Farm
Mar. 30, 2011, 04:46 PM
No offense taken, and as I mentioned I am no expert and probably mis-used the terminology from an article I read over three years ago. I am happy to be corrected by those who know better. :)

deltawave
Mar. 30, 2011, 05:55 PM
I'll take density over size any day. :)

A related question, of course is how bone density might be favorably impacted in a meaningful way. Many studies indicate that weight bearing exercise is one way to improve this. Yet there is still this myth that young horses should never be stressed or subjected to skeletal loading for fear of "hurting" them.

JER
Mar. 30, 2011, 06:50 PM
Well, I read all those damn studies and more, and used them to guide my program with my mare. Varied footing, concussion, weight-bearing exercise interspersed with rest, living out in mixed conditions, etc. And look where it got us.

While I have no idea about the lab-value quality of her bone, I do know that she looked right, in terms of bone, and had no soundness issues. Both of her parents were sound, strong horses with very long careers. Her dad did GP dressage to age 20. He was a very powerful horse and a number of his offspring have also had long careers at the top of the sport. Mum (very sound at 22) is tough as nails and, although not a large mare, has plenty of substance for her size and build.

Dekorum has two half-sisters, neither of whom have had a soundness issue in their 5 and 6 years of life. (The 6 year-old stepped on a nail once and was gimpy for a short time.) They are doing all the same things she did. I never saw any reason to be checking out their bones -- specifically their fetlocks. Do I have any reason to now?

deltawave
Mar. 30, 2011, 06:58 PM
I don't think there's any possible way to predict the sorts of random catastrophes that afflict horses (and people) beyond always observing, learning what we can from post-mortems, and following leads research-wise. We NEVER know enough for our efforts to save an individual. :(

Rosie
Mar. 30, 2011, 07:31 PM
RAyers,
Interesting POV on bone density scans.
I fractured my tibial plateau last year while landing after an oxer. No apparent reason - we jumped the fence just fine, I landed with my weight in my stirrups, felt a sharp pain in my right leg and then had no control over it. Pulled up and rode out of the arena. (I was at a show) Never fell off. Didn't touch a standard or pole. No other way it could have broken except it just fractured as I landed.
Sports Ortho surgeon said it was "just one of those freak things" and my bone seemed "pretty strong" when he put in the plate and screws during surgery.

I asked for a bone density scan and was told the results showed I have osteoperosis.
Not borderline. Definite.

(As a result, I'm on medication and have dropped down a couple of levels while jumping. And, a bit more cautious overall while riding.)

So. Freak accident or brittle bones? And, I'm guessing that this same type of "no apparent reason fracture" can and does happen in horses.

deltawave
Mar. 30, 2011, 07:40 PM
Yes, you are guessing. We have to do better than that, especially before doing widespread, expensive, not-risk-free, and completely unvalidated tests on other species. :)

D_BaldStockings
Mar. 30, 2011, 08:09 PM
I can't locate the original, but this gives the gist of a study from New Bolton, and the Grayson Jockey Club foundation:

http://www.bloodhorse.com/horse-racing/articles/54091/training-young-athletes


Stress properly done is good. Trauma is bad. LSD jogging does not build galloping bone.


And something copied for the earlier article, sorry I can't find it:

"Nunamaker devised a follow-up study that would examine the effects of speed work. He looked at four groups of 2- year-olds.
1. was left at pasture.
2., 3. trained at separate tracks, but both took part in long, slow workout programs.
4. workouts included short speed bursts three days per week (up to four furlongs at 13 seconds per furlong1/8 mile). 5280’ / 8 = 660’ = 220 yds

The results:
The pastured horses had undergone little bone remodeling,
both traditionally trained groups developed notable amounts of weaker periosteal bone. However, the cannon bones of the 2- year-olds in the fourth group (which were trained at speed) showed almost no (bad) periosteal bone growth; instead, they showed an increase in (good) lamellar bone development. In fact, their bone shape became very similar to that of most 4-year-olds which had been training and racing for two years.

Clearly: The speed work had added enough stress to prepare the bone for racing, without overdoing things to the point of causing bucked shins and periosteal bone growth.

The reason that speed work is effective, surmised Nunamaker, has to do with loading the front of the bone in compression with fast work rather than tension (stretching) as occurs during slow or little work. “So, horses on long, slow works remodel their bones for training, while horses that breeze more often remodel their bones for racing,” he explained.

How Much Speed? With short speed work the answer to effective bone remodeling, the next question is how much speed work would be the right amount to stress the bone just enough, but not too much?

Unfortunately, there is still no definitive answer to that – and probably never will be, since so much depends on the individual. Nunamaker's colleague, John Fisher, DVM, a race trainer, set out to see if he could develop an optimal program to use on the horses in his barn.

The schedule he came up with starts with basic conditioning. Once a horse could comfortably go one mile with furlongs at 18-20 seconds each, (2:30 /mi. or average 24mph) Fisher introduced speed work 2 X week, using a rate of 15 sec. per furlong (1/8 mile) 2:00 /mi. average 30 mph), and starting with one-furlong.
Every 3-4 weeks, he increased the distance by another furlong.
By the end of 3 months, the horse was doing 3-furlong bursts at speed, but only once every 5 days. (plus the initial conditioning to 2:30 so total about 4-6 mo.)

On non-speed days, the horse was either rested or galloped, allowing time for the stimulated bone to remodel. Over the years, Fisher has found this program effective in his barn. Shin problems have dropped from being practically the norm to being a rarity, yet he's seen no increase in injuries to his horses' ankles and knees."

D_BaldStockings
Mar. 30, 2011, 08:17 PM
JER

It was unpredictable, likely unpreventable.
I understand you will be hoping to find answers somewhere that can prevent something similar ever happening again. Remember you are only human and you did all you could; it is always good to add knowledge, but horses will still be horses.
You don't know where the event may have started: weeks, months ago a small error of step or who knows?

Horses will try too hard. They will self destruct, despite best efforts and all the most modern research applications.

I am sorry for your heartbreak.

JER
Mar. 30, 2011, 08:23 PM
Interesting summary with references, although compiled for a nutraceutical company.

Bone biomechanics: a review of the influences of exercise and nutritional management on bone modeling in the growing and exercising horse (http://en.engormix.com/MA-equines/health/articles/bone-biomechanics-review-influences-t311/p0.htm)

I know of other studies where they found that short, repetitive cycles of concussion led to bone remodeling for greater strength. I posted about this before, but I seem to recall they were human studies, not equine.

vineyridge
Mar. 30, 2011, 08:33 PM
Can bone density be affected by an exercise program even in mature horses? That is to say that if a horse is not started in work while it's growing and its bones are developing, can one obtain the same results later in life?

I have a personal reason for asking this. :)

deltawave
Mar. 30, 2011, 09:01 PM
Just offhand I'd say that bones never stop remodeling in response to stress. But an older bone does not have the same capacity for change as a younger one, generally speaking. Until full adulthood (not the same as the so-called "skeletal maturity", which is more about growth plates) there is maximum capacity for dynamic change. After that, less so.

But I am generalizing A LOT here, and I have no idea if horse bones are subject to the same ravages of aging as human ones. Horses, after all, are weight bearing practically 24/7, whereas we CERTAINLY are not!

ThirdCharm
Mar. 30, 2011, 09:18 PM
If I had a penny for how many times I've heard some variation of "You wanna see some crooked legs, go watch the jog-up at a CCI", I could retire. I'd love to see someone try to convince riders of an "acceptable range" of bone density when they don't even stick to the "commonly accepted" wisdom of acceptable visually perceived correct conformation, provided the horse gets the job done....

Jennifer

RAyers
Mar. 30, 2011, 09:31 PM
At no time is the bone in the body more than 10-15 years. This is because bone does remodel at a rate between 5-10% annually just as normal physiology. All large mammals are relatively the same in the bone biology/physiology so we can assume the same for horses.

vineyridge
Mar. 30, 2011, 09:37 PM
In long format, were horses trained for the steeplechase? Did people do really fast gallops regularly? Because if galloping fast affects bone density, maybe that would be one element to add to a training program.

D_BaldStockings
Mar. 30, 2011, 09:43 PM
Maybe some thoughts here:
http://www.bloodhorse.com/horse-racing/articles/54097/bone-and-fracture-treatment

When and how much stress to add in remodeling attempts is the eternal question.

Kairoshorses
Mar. 30, 2011, 09:52 PM
But an anisotropic heterogenous composite weenie.

By the way, vineyridge, this is a valid consideration and so don't take my critique as a personal comment.

Dang it, Reed you messed up my thinking, as thin as it was.

I don't know my biological heritage, so at 40, I got bloodwork and bone scans done for a "baseline"....fixing to get them all re-done to see how pathetic I am as I age.....

So you're telling me it won't tell me anything and I should suck it up?

Sigh. I HATE anisotropic heterogenous composite weenies when they tell me I'm full of crap.

BaroquePony
Mar. 30, 2011, 10:27 PM
Intelligence is a genetic defect, Darwin favors the median :winkgrin:.

BaroquePony
Mar. 30, 2011, 10:39 PM
I seem to remember someone on this BB mentioning something about Bruce Davidson getting his three year olds out fox hunting because he felt that the gallops helped build good strength of bone in youngsters starting under saddle. Not overdoing it, but definately getting started sooner than *old school* would stick with (horse shouldn't be backed until age four, and then started slowly and increasing development under saddle at a somewaht exponential rate of speed going into the fifth year).

fooler
Mar. 30, 2011, 10:44 PM
Interesting summary with references, although compiled for a nutraceutical company.

Bone biomechanics: a review of the influences of exercise and nutritional management on bone modeling in the growing and exercising horse (http://en.engormix.com/MA-equines/health/articles/bone-biomechanics-review-influences-t311/p0.htm)

I know of other studies where they found that short, repetitive cycles of concussion led to bone remodeling for greater strength. I posted about this before, but I seem to recall they were human studies, not equine.

JER - This was also noted in the EQUUS magazine study beginning with the 1st issue. They followed a Arabian colt from birth to around 5 years. They found bone remodeling as a result of ponying as a 1-2 year old. And IFFC different bone changes when he went to Arabian race training.

Of course as my old instructor used to say "this information and 25 cents will get you a cup of coffee." That was some time ago :D

BaroquePony
Mar. 30, 2011, 10:52 PM
It's been several decades since I have read the study discussing how overloading young horses with supplements and complete grains can actually cause problems with development in bone, and more specifically the growth plates, leading to various weaknesses. Something along the line of too much of a *good thing* doesn't allow for specific stresses in growth (or inhibiting growth) keeping the bone denser and more compact per square inch.

ETA: also, some lines of thoroughbreds (famous ones at that, but they pass it on) are known for having *weaker* bone

JER
Mar. 31, 2011, 02:14 AM
JER - This was also noted in the EQUUS magazine study beginning with the 1st issue.

I'm thinking of something more recent than that. IIRC it was fairly specific about intervals of concussion and it was a human study.

sisu27
Mar. 31, 2011, 10:03 AM
“So, horses on long, slow works remodel their bones for training, while horses that breeze more often remodel their bones for racing,” he explained.

So if this is the case perhaps horses that are born to jump the big fences should be jumping at a young age? I have always thought LSD was the only way (my horses don't need to gallop like a racehorse for a living) but jumping a young horse was always something that I thought was crossing that line. Perhaps that thinking is very wrong.

BaroquePony
Mar. 31, 2011, 11:01 AM
Posted by sisu27:

but jumping a young horse was always something that I thought was crossing that line

I was taught this too, but I thought it had to do with preventing any possible damage from stretching and concussion (which is what you want when building bone) to tendons and ligaments, both on take-off and on landing, before the horse has gained strength carrying itself, let alone a rider.

Also because the basically unschooled/young horse that has not yet learned to pay attention to it's own actions, let alone with a rider. Also preventing *farting around*, slipping, tripping or scrambling, whether in work or in the paddock in mud, or wherever.

JER
Mar. 31, 2011, 11:09 AM
Lucinda Green: French horses are trained to look after themselves (http://www.telegraph.co.uk/sport/othersports/equestrianism/3013863/French-horses-are-trained-to-look-after-themselves.html)

French-bred and -trained horses have been enormously successful in UK National Hunt racing over the past decade.

vineyridge
Mar. 31, 2011, 11:10 AM
There are two schools on this in European Steeplechasing. The French start them jumping very early on, and their horses chase at a comparatively young age. The Irish don't even pull their chasing horses out of a field to break until they are late three/early four, and they have a rather long progression up through the ranks before they get to big time competition. It would be interesting to see the breakdown stats on chasers, there AND here, since here chasers are usually older horses who have failed at flat racing--not specially bred for the sport as the Europeans do. Another interesting difference between here and over the pond chasing is that there non purebreds can race, and here only pure TBs are allowed on the track at recognized races. Stats on breakdown differences between the PBs and the NTR/AQPS horses would be very interesting reading if they are available.

But for information on lots of horses running at jumping at speed, chasing is the closest comparable to eventing. Only there, you usually don't have the technical complications of eventing XC.


So if this is the case perhaps horses that are born to jump the big fences should be jumping at a young age? I have always thought LSD was the only way (my horses don't need to gallop like a racehorse for a living) but jumping a young horse was always something that I thought was crossing that line. Perhaps that thinking is very wrong.

vineyridge
Mar. 31, 2011, 11:15 AM
JER, we posted at the same time. I hadn't seen the Lucinda Green articles, which explains the difference a lot better than I ever could.