I wrote a research paper when I was in college on Epiphysitis (development
of slight lameness and swelling at the lower end of the inside of the cannon
bone and the upper end of the long pastern bone). The epiphysis is a
portion of bone separated from the long bone at birth. As the horse grows
and matures, these bones are joined by bone tissue. The epiphyseal junction
is located just above the horses knee. This junction is open at birth and
gradually closes as the foal grows. When the junction is completely closed
the foal has reached its full height. The long bones grow in 2 ways. By an
increase in diameter and by an increase in length. The bone primarly at
either end of the bone and the growth occurs at the cartilaginous
separation. This is referred to as the epiphyseal line. The increase in
length is a result of growth of the epiphyseal plate which is then converted
to bone. Each plate has its own growth life span. The one at the lower end
of the cannon bone stops growing and dissappears around 7-12 months of age.
The one at the lower end of the radius closes around 24 months.
In researching for this paper I discovered several things. If you break and
start training your horse before these bones have had a chance to fully
close, you are taking a chance of having the horse develop Epiphsyitis which
treatments can vary (medication or surgery). The time of closure of these
bones can also be connected with breeds. Standardbred horses tend to close
before Thoroughbreds; Thoroughbreds before Quarter Horses and Arabs are
practially last on the list for closure. The owners of racing Thoroughbreds
will usually have X-rays taken of the fore arm when determining when they
will start racing their horses. There are 3 classes that the X-ray will
place the horse in: Class A- sound and normal epiphyseal development with
epiphysis completly closed. Class B- Minor evidence of epiphyseal
immaturity. The epiphysis is closed in the center and open at each end.
Class C- Gross evidence of epiphyseal immaturity and gapping. The epiphysis
is wide open. The trainers use these classes to determine the extent of the
horses training in order to keep a sound horse.
Like I said above, Arabs tend to be slower in their leg development. I
attended Cal Poly Pomona and worked with the Arabs there. It was a standand
policy that all horses were ground worked from the day they were born until
they turned 3. Only after they turned 3 where they saddled and their riding
career began.
In my opinion, why take a chance of lameness in a young horse by riding it
too young. As a 2 year old, you can increase its gound training by lunging
with a saddle to prepare it for riding. If you give your horse one extra
year to finish maturing you might have a horse that will give you many more
years for excellent riding.
Carol
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Carol Robertson <roberc@pacific.net> Kelseyville, CA