Most horses are sided, the same as most people. Often, I find it's the left side that's dominant and bigger (and I have the templates to bear that out); but whether it's left or right side, their larger/dominant side is usually the side to which they bend and track well, while going in the opposite direction - and having to stretch that contracted, muscle-y side - is harder. And whatever discipline we ride, one of our goals should be to make our horses as evenly developed as possible. (If this sounds familiar, I did touch on some of this in my "Ground Work and In-Hand Exercises" post from April of '09). And to that end, dear readers, we do NOT want our saddles to be adjusted asymmetrically ... at least, unless we have a saddle fitter on retainer, and a huge disposable income and nothing better to spend it on than eternal saddle fit adjustments!
There are plenty of fitters out there who'll adjust your flocking - and in some cases, even your tree - to match your horse's asymmetries. (NOTE: Anyone who tries to adjust a spring tree asymmetrically will in all likelihood make the tree so it can't sucessfully be straightened, and it will probably never sit correctly again. Most spring trees should only be adjusted once - symmetrically - no more than one tree size.) And while there may be a short-term benefit to that, doing so - in my opinion - can cause more harm than it alleviates. Why? Consider this:
You have a nice mare who had some soundness issues that took about 6 months to correct. As a result, her right side is considerably larger and more muscled than her left; she goes along quite happily to the right, but going left is a nightmare. So you get a saddle that fits her right side well, but the left ... well, there's a 3/4" gap. So the fitter says, "I can make that gap go away!" and proceeds to either flock that side heavily to compensate, or tweaks the tree so the left side suits the lack of muscle. The saddle fits perfectly, the fitter goes away, and you start working your mare five days a week.
For the first few weeks, things are going pretty well. The mare's getting better about tracking left, her muscles are growing and she's getting much more balanced. Then, you notice she's getting fussy about bending left, and she no longer picks up the left lead canter as easily as she did, and you're starting to feel as though you're sitting a bit crooked. You run your hands down your mare's back under the front of the saddle, and notice that the left side feels awfully tight. You remember that the saddle was fitted asymetrically, so you call your fitter to come address the issue. Fitter comes out, adjusts the flock / tree, charges you between $100 and $400, and everything's fine. A few more weeks down the road, the mare's starting to have issues going to the left again, and the left side of the saddle feels tight again. You call your fitter, fitter comes, charges you another $100 - $400, and all's well. A few more weeks pass, and the issues are starting again ... You call your fitter, but this time, your fitter can't get to you for a month. So you soldier on, with your mare getting more and more sour about bending left ... and then bending right ... and then being saddled at all. By the time your appointment rolls around, your mare's so sore and cranky that you have to cancel because your vet / chiro told you (after a $250 visit) that she at least two weeks off to heal - or worse, that she's seriously aggrivated whatever it was that caused the 6-month lay-up. Or perhaps your mare was in so much pain that she started bucking, launched you into the arena fence, and now you're laid up with a concussion / broken collar bone / broken ribs / separated shoulder (which isn't nearly as painful as the cost of a visit to the ER was). You (and/or your mare) are out of commission, you've lost training time, and the asymmetry is still there.
Here's a second scenario:
Same mare, same issues, same asymmetry. Again, you get a saddle that fits her right side well, but the left ... well, there's a 3/4" gap. So your fitter says, "Why don't we address this issue with a shim pad?" You buy a correction pad for $130, put 3 shims in to fill the gap, and off you go. A couple weeks later, you notice the left side of the saddle's getting a little tight, so you remove one of the shims. A few weeks later, the muscle's grown enough to remove another shim; finally, 10 or 12 or 14 weeks after the initial fitting, you can remove the last shim pad. Your fitter comes out, tweaks the flock, charges you between $100 and $200, and you're good to go for about 6 or 8 months - longer, in some cases.
You do the math.
I've posed the "to adjust asymmetrically or not" question to several other fitters, and I received this from my mentor Patty Barnett, who owns and operates East Crow Saddlery. It's pretty much the same answer I've gotten from everyone else, but I feel it really makes a nice sum-up:
"But never ever is it acceptable (imho) to adjust a tree asymmetrically to fit a horse. This is basically the same thing as twisting a tree on purpose. Say "twisted tree" to someone and watch their eyeball's pop out of their head. Now tell them to pay someone to twist their tree on purpose ...
"I don't often flock a saddle asymmetrically to fit a horse, but certainly have done it. On a young horse, I would much prefer they use a corrective pad to stabilize and hold the saddle centered and straight. And then work on training to get the musculature more even. But there are people who don't want to spend additional money on a corrective pad, or they feel the saddle should fit without a corrective pad. After all, what are they paying the saddle fitter for? It's like blasphemy for a saddle fitter to utter the words "corrective pad" ~ we've confessed our sins of associating with the devil.
"I have a handful of clients though that their horses are in their 20's or have permanent asymmetries ~ so yes we've very precisely flocked the saddle very unevenly to fit their horse. But they also know they can never ride another horse in that saddle unless it's reflocked again.
"I could go on for another hour down a few interesting side roads of uneven feet or bad farriers causing uneven shoulders & muscling. One of my favorite types of clinics to attend are farrier/foot clinics. "No foot, No horse" is still as true as ever. Whole horse soundness and the importance of the fitter working with the farrier, dentist, vet, muscle worker, chiro ..."