I just have to get my 2cents worth in:
There are 3 types of saddle bottoms - all saddles, all types of
riding throughout all of history: panel (english & Australian saddles
plus the Marciante endurance saddle which looks western), sidebar
(Orthoflex, Boz, SR, Skyhorse, McClellan, Stonewall) and skirted
(western, Sharon Saare, Synergist, DeSoto, Zes), then there is the
Sports Saddle which is sort of like the earliest saddle - a pad on the
horse's back with no tree at all (the Sports Saddle has a pommel and
cantle but not a complete tree).
Each is intended to fit the horse in a particular way which makes
it suitable for certain horse shapes and riding activities. The panel
saddle, which is also descended from the original pad saddle, sits on
top of the back with a padded panel running on each side of the
"spine." The saddle rests behind the withers. The original saddle was
developed in England about the same time the Thoroughbred was being
created and today most saddles of this type are built for narrow,
fairly large horses doing jumping sports. For endurance, the panels
can be too small for adequate weight distribution and the tree can be
too long but in general, this type of saddle, I think, has the best
potential for good rider weight distribution if the saddle really fits
the horse. The sidebar saddle is descended from the pack saddle and
consists of bars that rest on the sides of the horse's back, lower down
than the panels of a panel saddle rest and which extend further forward
over the shoulders and further back over the loins than panels. These
bars can be connected to the tree of the saddle with articulated joints
that allow independent movement. Since the bars are straight, if they
are large, the only shape horse they will fit well is also straight.
Joyce Harman, DVM, an endurance vet and rider, says "Arabs tend to be
'shapely' - lots of curves in a short space because of their short
backs which makes for a less than perfect fit, especially for Orthoflex
saddles from what I have heard. Skirted, or "western" saddles descend
from the saddles of the medievel European knights and, as they
developed in our West, were designed to be sturdy enough for all
purpose ranch work, including roping. Unlike both the other types,
skirted saddles do not have fit built in - they are barrel shaped
underneath, on purpose because for the cowboy his saddle had to fit
lots of different horses. The fit is provided by the saddle blanket!
That's just part of the story of saddle fit. Round backed, low
withered horses are the hardest to fit because there is very little for
a saddle to "lock onto." And short backs are hard too because most
saddles are made for bigger horses. I'm not surprised at what you
discovered about which type saddle fits which shape horse.
For anyone in the market for a saddle, or just interested in
saddles, my book "Choosing a Saddle for Endurance & Long Distance
Riding," (listed in the books section on the Endurance Homepage)
includes more than the above about each saddle bottom type as well as a
lot about how a saddle should fit a rider and a questionaire that
should help you end up with the right saddle.
Happy trails!
Laney