- Dr. Frank N. Furter, Rocky Horror Picture Show
If you're looking for information about assessing saddle fit, you can find tons of it on the Internet. From medical research papers to blogs like mine, information abounds. And for the most part, it all agrees on the major points: the saddle should spread the rider's weight evenly over a sufficiently large bearing surface while keeping the horse (and ideally, the rider) as comfortable as possible so s/he can perform to the best of his or her ability. But when it comes to the method(s) used to assess fit ... well, there are a LOT of them, from computerized high-tech imaging to low-tech human hands-on. And how good are they? Let's take a look.
Veterinary diagnostics have improved by leaps and bounds in the last decade or so, and some of these diagnostics are now used in assessing saddle fit - thermography, in particular. Thermographic images show heat - blue areas are cool, shading to red, which is hot, to white, which is hottest (note the handy-dandy scale on the right of the image). Heat can translate as pressure when it comes to saddle fitting:
Given the pattern here, it would be reasonable to think the saddle might be bridging; it's also showing pressure further forward on the right than the left.
The image above is showing a lot more pressure on the left panel than the right, with some bridging on the right as well.
This image is showing more pressure on the right, with some serious heat/pressure down the rear of the right flap.
And just for comparision, here's a thermographic image of a horse's back. This image isn't saddle related, but it shows some heat along the spine, which would be consistent with a problem like kissing spine:
The Pliance system is another computerized method of measuring pressure. You can find out more here (the site is sadly rather incomplete). This method looks sort of like "thermography in motion", it's basically a pad that measures pressure while the horse saddled and working with the rider up.
Another popular device to assess fit is the Port Lewis Impression Pad (lots of info here, and photos of the pad showing pressure spots here). It's a plastic pad that's filled with a clay-like substance used to make dental impressions; you use it in place of a regular saddle pad, and the dental clay moves away from areas of pressure.
All of these devices and methods can give you a pretty accurate idea of where heat / pressure is occurring. However, what these don't tell you is why the pressure is occurring. Is the issue an ill-fitting saddle, or is it something else?
In the first photo, the bridging shown could be a saddle fit issue,. It could also come from a horse who's traveling inverted rather than lifting his/her back ... and that could be happening because of a saddle fitting issue, a training issue, or a rider issue. The pressure showing further forward on the right could be a saddle issue ... or it could be that the horse is muscled asymmetrically, or it could mean that there's a gait / soundness issue. Equally possible is that the rider is sitting with one hip further forward than the other and is causing the saddle to twist.
The second photo - heavy pressure on the left, a little pressure and some bridging on the right. Could be a saddle issue - perhaps the panels aren't flocked evenly ... or it could be an asymmetrical horse, or a rider who sits more heavily on the left seatbone.
The third photo could be caused by any of the issues mentioned above, but the high level of heat showing on the rear of the right flap makes me curious. Does the horse have a physical issue - broken rib, perhaps? - or does the rider have a vise-like right leg?
The Pliance system - what little info I can find on it - seems to have the same drawback as thermography: it shows the symptom but not the cause.
Now, the Impression pad: again, it shows where there's pressure, but not why there's pressure. It could be a saddle fit issue, or a rider issue, or a horse issue ... or it could be that the saddle really isn't a terrible fit without the rather substantially thick Impression pad under it!
That sort of whittles it down to the old low-tech, get-the-saddle-fitter-involved method. Sometimes we'll consult with your vet, and some use the Impression pad, but it's pretty universal that we'll take a look at the saddle, feel around, watch you ride (unless the saddle is such a glaringly bad fit that we don't want you to bother mounting, or your horse is really backsore), feel around again, look at your horse's back, and determine not only where the pressure is, but what's causing it. Sometimes it will be a quick fix: a flocking adjustment, or a tree width adjustment. And sometimes, you'll get input that you may not really want to hear - you might need a new saddle, you might need to do some serious work on your riding and body use, your horse might need some remedial training ... or you might need to get your vet out, because it doesn't look like it's the saddle, after all.