Many horse people have heard that dry spots under a saddle are cause for concern, and we fitters are often asked to interpret odd-looking dry spots on a horse’s back, and even dirt patterns on saddle pads. These things can sometimes provide cause for concern, and perhaps a clue to saddle fit, but this is not always the case.
First, let me address the dreaded dry spot. Dry spots may point to an area of pressure, but they can also just be in a spot where the saddle doesn’t move much across the horse’s back; or rarely, a horse may have prior nerve damage that inhibits sweating. If you notice dry spots, put your horse’s saddle back on, with no pad or girth. Stand on your horse’s left side and place your left hand with some pressure on top of the seat, to simulate a rider in the saddle. Slide your right hand underneath the saddle from the back of the flap and run it the whole length of the saddle, feeling for any difference in pressure on that hand. If you discover a dramatic difference in pressure over that dry spot, it may (may!) indicate a pressure point that your fitter should investigate.
Second, the dirt patterns on your saddle pad. It is entirely normal to see more dirt on the pad where your saddle’s seat was. After that, you would ideally like to see a fairly even front-to-back and right-to-left dirty area. However—and this is a big however—there are many benign reasons you might not see such a pattern. For instance, many people notice more dirt on the right side than the left. Did you start grooming on the left and run out of steam a bit as you switched to the other side? Another frequent scenario: more dirt under the seat on one side versus the other. Is your saddle bad, or do you collapse your opposite hip and lean that way? Or, have you forgotten to switch your stirrup leathers in a while, and your left one is now all stretched out from repeated mounting? Don’t ignore the dirt patterns on your saddle pad, but take a little time to think through possible causes before you assume you have a saddle fit problem.
If you do see anything under your saddle pad that puzzles or concerns you, have your trainer assess how you and your horse are moving, looking for asymmetry in both of you, and any signs of stilted gaits or pain in your horse. If you and your trainer think that perhaps the saddle is not as balanced and comfortable as it should be, then it may be time to call your saddle fitter.