Re: Horse Height & Bone

[Susan Evans Garlinghouse <suendavid@worldnet.att.net>]

B. Miskimmin/J. Curtis wrote:
> 
> Susan,
> I was wondering whether there is a published report or journal paper for
> your research at Tevis?  Maybe it's in prep - data still being worked up?
> Sure would be nice if it was available as a PDF file or otherwise on the Net!

The data is being published in two journals---the first paper,
"Relationships between condition score and weight-carrying ability in
160-km endurance races" was accepted by the International Conference of
Equine Exercise Physiologists, which is in the process of being edited,
so won't be actually printed for awhile.  This was the paper that I
presented in Japan in September.

The most recent paper, "The influence of body measurements and condition
score on performance results during the 1998 Tevis Cup" is being
published in the proceedings of Equine Nutrition and Physiology Society,
but also won't be printed and on the shelf for awhile.

I'm going to be one of the speakers at this year's nat'l convention, and
the topic of my talk will be the results we found in measuring and
analyzing these 600 Tevis horses, so if you can make it, it'll all be
covered in detail then.  Also, I've talked to Doyle Patrick about
writing an article for Endurance News, it should be finished and showing
up in EN fairly soon, knock on wood.


> 
> Can you comment on recommended minimum bone size for a given horse height?

One of the interesting things we found was that there was a relatively
small range of cannon bone size regardless of height---the average
circumference (measured midway between knee and fetlock) was 7.43". 
Really small horses had smaller CBCs, really big animals (like Ruby the
mule) usually had larger CBCs.  I think the minimum cannon size I saw
was about 7 1/8" in a 14.1 horse in '95, I seem to remember she finished
but I don't have my data set right here in front of me.  Ruby was the
largest cannon we measured all three years, she was somewhere around 8
3/8", but there were other horses with cannons almost as large that
didn't finish.  We were unable to accurately measure height, but the
vast majority of the horses, both finishers and pulls, were between 14.2
and 15.1.  So based only on the data that we saw, if your horse fell
between roughly 14.2 to 15.1, then I'd really want to see a CBC
somewhere around 7 1/2".  If the horse was smaller, then a little less
might be okay, if the horse was larger, then a larger CBC is called for.

However, we did NOT see a statistical difference in CBC alone between
finishers and pulls, so CBC alone is not a predictor of success at
Tevis.  Our conclusions were that CBC is important, but that there are
many other closely related factors that can nullify the effects of
CBC--ie, foot size, joint angles, shoeing, bone density, integrity of
associated soft tissue, etc.  In other words, a 10" cannon won't help if
the foot is the size of a half-dollar and the shoulder and pastern are
both the same length!;-)

> Also interested to know more about your comment that taller horses (how
> tall?) in general had more lameness problems than smaller ones at Tevis.
> Was the difference statistically significant, and how did bone size or
> other variables correlate?

No, not TALLER horses---LARGER horses, which is not necessarily the same
thing.  In most cases, the heavier horse is also going to be taller, but
we did not measure height.  We started to the first year, but there were
too many problems getting consistent measurements, so the data was
thrown out.  Our data was based on the weight of the horse, the weight
of the rider/tack, the relationship between the two, and the
correlations to performance.  The first two years we analyzed weight
data, we tried every which way but Sunday to find correlations between
weight load and performance and couldn't find it.  Weight just didn't
make a damn bit of difference to completion rate, speed, finishers vs.
pulls---anything. Whether we would find different results if we measured
horses at different types of rides (flat, humid, sandy, whatever), we
don't know, since we haven't yet measured at rides other than Tevis. 
(Whether I ever will, I don't know---I'd like to, but I've already spent
about $10,000 of my own money funding this research (no, I am not rich)
and there's rapidly reaching a point at which I'd rather be spending my
money paying for entry fees instead.)
 
This past year we tried analyzing the data from just this year a
slightly different way and we THINK we've found a difference (yes, a
statistically significant one) in that HEAVIER horses are more prone to
lameness, regardless of the weight of the rider.  In other words, rider
weight still doesn't make much of a difference, but the weight of the
horse (which is, after all, the majority of the weight load) might be a
factor.  Now, whether that also means taller horses, I have no idea. 
There could be a lot of other factors that need to be considered, such
as stride length, stride frequency, biomechanics in the hoof, not to
mention a ton of things up in the back, etc.  I'm going to go back and
see if the same relationship existed in the previous data, but I haven't
done that yet.  It'll be done by the Reno convention.

One other thing that we tried to prove or disprove this year was whether
you could relate a certain cannon size to weight to predict performance
or likelihood of lameness, and we couldn't do it.  Again, cannon size is
an important factor, but there are so many other factors as well, you
can't predict performance from ONLY cannon bone and weight.

And once again this year, we looked at condition score and found that on
average, horses with a moderate condition score did MUCH better than
thin horses.  In other words, scarecrows are much, much, MUCH more
likely to run into metabolic failure and be pulled than are horses that
don't have their ribs showing.

Hope this answers your questions more or less?

Susan G