stumble bum and bone maturity explanation

[Bob Davis <bsdavis@kansas.net>]

Title: stumble bum and bone maturity explanation

   First off, I want to say thanks for all reply posts to me (and my mustang's) stumbling query.  Hudson was shod yesterday.  I rode today with NO, not one, stumble.  I also put the saddle back a little farther and I could feel the difference in his carriage on the front.  We didn't work hard or go very far, just rode easy walk and with a few, rather spirited trots thrown in, for half hour.  He was my happy camper again most of the time, although i did get a little resistance going out on one of the trails...
But it was a good day over all.  Vet and farrier said conformation is not a problem, great legs and great feet.  Both agree he's still a little overweight, but not terribly.  I feel better, but what's more important is he obviously feels better.  Thanks again.  Now can anyone recommend a pre-race electrolyte with proper Ca:Phos ratio?  Not for Hudson yet but another hose I will be riding in a 25.

I also wanted to pass on an article posted to the CD-L (driving) list serve that I thought was very interesting.  


This was written by a Veterinarian and professor at one of our
country's most prominent universities...

"Owners and trainers need to realize there's a definite,
easy-to-remember
schedule of fusion - and then make their decision as to when to ride
the
horse based on that rather than on the external appearance of the
horse.
For there are some breeds of horse - the Quarter Horse is the premier
among these - which have been bred in such a manner as to LOOK mature
long before they actually ARE mature. This puts these horses in
jeopardy from people who are either ignorant of the closure schedule,
or more interested in their own schedule (for futurities or other
competitions) than they are in the welfare of the animal.

The process of fusion goes from the bottom up. In other words, the
lower
down toward the hoofs you look, the earlier the growth plates will
have
fused; and the higher up toward the animal's back you look, the
later.  The
growth plate at the top of the coffin bone (the most distal bone of
the limb) is fused at birth. What this means is that the coffin bones
get no TALLER after birth (they get much larger around, though, by
another mechanism). That's the first one. In order after that:

2. Short pastern - top & bottom between birth and 6 mos.
3. Long pastern - top & bottom between 6 mos. And 1 yr.
4. Cannon bone - top & bottom between 8 mos. And 1.5 yrs.
5. Small bones of knee - top & bottom on each, between 1.5 and 2.5
yrs.
6. Bottom of radius-ulna - between 2 and 2.5 yrs.
7. Weight-bearing portion of glenoid notch at top of radius - between
2.5
and 3 yrs.
8. Humerus - top & bottom, between 3 and 3.5 yrs.
9. Scapula - glenoid or bottom (weight-bearing) portion - between 3.5
and 4 yrs.
10. Hindlimb - lower portions same as forelimb
11. Hock - this joint is "late" for as low down as it is; growth
plates on
the tibial & fibular tarsals don't fuse until the animal is four (so
the hocks are a known "weak point" - even the 18th-century literature
warns against driving young horses in plow or other deep or sticky
footing, or jumping them up into a heavy load, for danger of spraining
their hocks)
12. Tibia - top & bottom, between 2.5 and 3 yrs.
13. Femur - bottom, between 3 and 3.5 yrs.; neck, between 3.5 and 4
yrs.; major and 3rd trochanters, between 3 and 3.5 yrs.
14. Pelvis - growth plates on the points of hip, peak of croup (tubera

sacrale), and points of buttock (tuber ischii), between 3 and 4 yrs.

....and what do you think is last? The vertebral column, of course. A
normal horse has 32 vertebrae between the back of the skull and the
root of the dock, and there are several growth plates on each one, the
most
important of which is the one capping the centrum. These do not fuse
until the horse is at least 5 1/2 years old (and this figure applies
to a small-sized,
scrubby, range-raised mare. The taller your horse and the longer its
neck,
the later full fusion will occur. And for a male - is this a
surprise?  -- You add six months. So, for example, a 17-hand TB or
Saddlebred or WB
gelding may not be fully mature until his 8th year - something that
owners
of such individuals have often told me that they "suspected" ).

The lateness of vertebral "closure" is most significant for two
reasons.  One: in no limb are there 32 growth plates! Two: The growth
plates in the limbs are (more or less) oriented perpendicular to the
stress of the load passing through them, while those of the vertebral
chain are oriented parallel to weight placed upon the horse's back.
Bottom line: you can sprain a horse's back  (i.e., displace the
vertebral growth plates) a lot more easily than you can sprain those
located in the limbs.

And here's another little fact: within the chain of vertebrae, the
last to fully "close" are those at the base of the animal's neck
(that's why the long-necked individual may go past 6 yrs. to achieve
full maturity). So you also have to be careful - very careful - not to
yank the neck around on your young horse, or get him in any situation
where he strains his neck"<
Dom