First in saddle fit, it is important to consider the anatomy of your horse's back. Back length, wither height and shoulder angle are all very important in saddle fit. The bars of the saddle should ride along the top of the rib heads supported by the long muscles of the back. The front of the bars will sit in the pocket just behind the shoulder and below the wither. The bars should not extend beyond the flank nor should they create pressure on the loin. The paddle like portion of the scapula moves in an arc over the front of the rib cage with the horse's stride. The flatter (more laid back) the shoulder is, the longer the stride length and the more movement of that shoulder. Pressure in this area will affect stride length.
There is a wide variation in body types and styles within our equine population. Some horses are high withered and narrow shouldered, some are muttoned withered with huge bulldog shoulders. It may be hard to believe but horses used to be selected for breeding based on their backs. A horse was said to have a good back for riding with moderate withers and a good pocket behind the shoulder for the saddle bars. Muttoned withered horses were considered cart horses because it was difficult to get a saddle to stay in place on their back. Often in the discussion of saddle fit you will hear folks talk about how the horse's conformation today is much different than it used to be, presumably because folks have quit selecting for back conformation in their horses. I don't believe this to be a universal problem across the breeds. I think many families of the Quarter Horse have lost the nice withers that they were bequeathed from the Thoroughbred and certainly there has been increased selective pressure in that breed for that "bulldog" look. Today's Quarter Horse often doesn't resemble the foundation type in many ways; back conformation among them. They tend to be lower withered and wider, flatter backed then their ancestors so using an old saddle or one of old type will have a bar angle that is too steep for a flatter backed horse. I think for my breed of choice, the Morgan, the opposite is true and our horses may have a better back with higher withers than many of their ancestors did. So, generalizations are not appropriate. You need to consider each horse as an individual.
Chico has a longer back than the other two and is fairly straight through the back. He has tall withers with a good shoulder angle that requires quite a bit of room for movement. Chico's saddle fit issues are not in his back, but in his hoof. He has a tendency towards clubbiness in his left front foot creating unevenness in his shoulders and back. Those high withers have been a struggle as well!
The majority of horses are left handed. In general (and this is a broad generalization) you can tell the horse's handedness by the direction that the mane falls naturally. If the mane falls to the right, the horse is left handed. Chico is very very dominant right handed and his tendency to be clubby in his left front foot is either the cause or the effect of his right handedness. Because of this we had severe lead issues through the first 4 years of his time under saddle. If you stand at his rump and sight down his back towards his shoulders you can see the difference in the two shoulders. His right shoulder is thicker and has more range of motion. His left shoulder is atrophied yet sits slightly higher and has slightly less range of motion. Riding in a poorly fit saddle for many years exacerbated this atrophy and I've had a hard time rehabilitating the shoulder to get them more even again. I do think I've seen some progress in that area since my saddle fit journey began.
Recognizing Poor Saddle Fit
There are many ways you can tell if your saddle is causing problems for the horse. For Chico I first noticed white hairs at his withers. White hairs are caused by pressure points from the saddle and indicate chronic pressure damage or damage that was inflicted months ago. It takes sometime for those white hairs to show up. A common spot for white hairs to develop is at the hollow behind the shoulders where poorly fitted saddles have been interfering with shoulder movement. Behavioral or gait changes are often the reason that I am called out to evaluate a horse for back pain and saddle fit. Hollowing of the back during saddling, dancing around or pulling away during saddling or puffing up at the cinch during tightening can all be indications that your saddle is causing your horse physical discomfort.
Under saddle a sudden reluctance to lope, or extend gait or pick up a certain lead may indicate pain due to saddle fit. Sometimes the horse has spent so much time in pain from a poorly fitted saddle that they become a chronic bucker. If your horse is kicking out or bucking suddenly under saddle, ruling out physical pain should be your first thought before trying to "train" the buck out of them.
Other signs of back pain may include head tossing, teeth grinding, agitation as the ride progresses,or horses carrying their heads too low trying to stretch out those back muscles. What does your horse do as you mount? Does he pull away from you, buckle at the knees, grunt or hollow his back?
A properly fitted saddle should not need a crupper or breast collar to stay in place when riding on flat ground. It also should not require an excessively tight cinch.
After riding and removing your saddle you should always examine your horse's back. Is his sweat pattern even? In a horse with a healthy back with no previous damage there should be even sweat patterns on both sides of the horse, especially where the bars are located. If it's been a long ride, the entire area under the pad will probably be sweated up but it's the bar areas that you are most concerned with. Unfortunately if a horse has experienced previous saddle damage, those areas will not sweat and that doesn't recover with correcting the saddle fit issue. Check all along your horse's back for areas of raised lumps, excessive heat, rubbed hair or tenderness to the touch.
This palomino horse is showing areas of dryness at the fronts of the bars. This area is not sweating due to too much pressure. This may be a single incident or the result of chronic saddle fit.
Tools for fitting your horse to his saddle
When I found the white hairs at Chico's withers I assumed he was too narrow for Quarter Horse or Semi Quarter Horse bars causing the saddle to rock down on his withers. Consequently I found a narrow saddle that I felt didn't hit his withers but was supported all along his back. I thought I had solved our saddle fit. But, because this saddle had a fairly steep bar angle it dug into the pocket and limited his shoulder movement. This saddle was also very long so I had to put it further up over his withers than I would normally increasing the pressure on his shoulders. Eventually this made his problem even worse to the point that his stride was so severely shortened that I had to correct it with time off and chiropractic and massage. I never had dry spots under my saddle. I never had bucking issues or saddle slippage or white hairs. It just changed my horse's stride to the point that he couldn't perform. By trying to fix my saddle fit issue without fully understanding the root of the problem I made it worse. I also made his back even harder to fit because it caused further atrophy to that shoulder. You would think that they would teach this stuff in vet school so I didn't have to learn it the hard way!
But, because of that journey I have learned more and more about saddle fit and am better able to help both my horse and my clients. I have also done some limited work with thermal imaging and feel this is a great technology to aid is saddle fit diagnosis and determine how to correct the problem.
The very first thing that I did to try to determine exactly what type of saddle I was going to need for Chico was to do a tracing of his back. This is a very valuable exercise that will help you to determine what kind of back your horse has. It requires such high tech equipment as a length of outdoor plastic coated wiring and a tape measure. You can get some of it at the hard ware store. It's thick and malleable and it will help you to determine the shape and angle of your horse's back. This website gives you directions to walk yourself through the process. http://www.outwestsaddlery.com
Basically you take a length of this plastic coated wire and create a tracing your horse's back from the base of the bar along the withers at the sweet spot where the front of the bars will rest in the pocket.
What I was very surprised to find out was that the relative shape of all our horse's back's was remarkably similar when measuring at the correct spot. Although Chico's tracing did illustrate some atrophy at the point of the withers and his wither height was a little higher, the angles and width were the same. He doesn't need a narrower saddle, he just requires a little higher clearance in the gullet so it doesn't hit his withers.
Using the tracings I had done of our horses I was able to check all our saddles for each horse to see what saddle fit which horse the best. Again, the website goes into more description of this process, but basically you take the tracing of the horse's back and place it in the bottom of your saddle.
A new emerging and gaining in popularity modality for saddle fit is thermal imagining. This can be very useful tool in determining pain in a horse's back and if it is related to saddle fit. A thermal imaging gun is one that measures hot spots on the horse's body and on typically on the saddle as well. Usually a horse's back is scanned for an image prior to riding and then after a period of 30 minutes of exercise. Then both the back and the saddle are evaluated. Images such as these are useful in determining how that saddle is interacting with the horse's back.
The image on the left is a saddle that is bridging on the horse's back. The red areas indicate areas of greatest heat. The image on the right shows a saddle with fairly good fit along the entire bar length with the exception of a a little extra heat in the right front of the bar. Suppose this horse is right handed? Or does this rider tend to lean on that side just enough out cause extra pressure there? With the good distribution in weight it is probably not a significant issue, but still an interesting finding.
Many people who are struggling with saddle fit are lured into the flex tree or treeless saddle option. Some even decide to just forgo the saddle and ride bareback. Let's take a minute and discuss why these are not good ideas for most riders. If the majority of your riding is for 30 minutes or less on level ground with low impact, then you do not need to read any further. Limited riding of that sort can be done bareback or in in a treeless saddle with no ill consequences. If you ride a little harder than that, keep reading.
First of all, let's diffuse the myth that bareback is more comfortable for either the horse or the rider. While I do fully recognize the benefits of bareback sessions for developing rider balance and harmony with the horse, these sessions are best kept to short rides in the arena or jaunts down to the lake for a swim. I spent a lot of time bareback as a kid and I suppose when you only weight 75 pounds it's a moot point. The entire purpose of a saddle is to distribute the weight of the rider's seat bones over a larger area on the horse's back. Without a saddle tree all the weight of the rider is consolidated into one area thereby increasing the pressure points. It's like the difference between going on a long hike with a properly fitted external frame backpack spreading the weight over shoulders, hips and back or carrying that same weight in a purse slung over one shoulder. This is a well documented fact and many recent studies have been done to scientifically confirm what should be common knowledge. Here is a link to a study completed using pressure pads to measure mean pressure points along the horse's back both with a saddle and without. http://www.ncbi.nlm.nih.gov/pubmed/22796121
A treeless saddle creates similar problems. Not only are they more likely to cause pressure at a single area because they lack a real tree they are also prone to slippage and create more difficulties with the need for an excessively tight cinch in order to keep the saddle in place. Again, especially for folks doing a lot of long hours in the saddle, this is not a good choice.
Flex trees are another option people commonly turn to when fighting saddle fit. The important thing to remember about flex trees is that they are not meant to "conform" to your horse's back. The flex trees are a solid traditional tree with areas that will flex slightly (and we're talking millimeters) or trees made entirely of a hard neoprene. Think of a hard sole to a work boot. More flex than wood, but not a lot of give. The idea with a flex tree is that it moves with your horse. Of course, it is also going to move a little with the rider's weight. Therefore if you are off balance at all a flex tree would increase that problem of uneven weight distribution for the horse. Many people believe that a flex trees allows for movement in the horse's back for a better athletic fit.
Let's look at where the bars of the saddle ride on a horse. The bars rest on a fairly stable area on the horse's back. If you have ridden bareback you know that while there is some flex and movement there, it is minimal. A horse can round or hollow his back and arc his rib cage laterally slightly. The flex tree is allowing for flexion outward or at the leading edge of the bar to allow for movement of the shoulder. We have already determined that proper placement of the saddle and proper fit require the saddle to be out of the way of the shoulder. If your saddle is interfering with shoulder movement then it doesn't fit properly and it will not help to have it flexing a few millimeters.
While I don't believe a properly fitting flex tree will cause problems for the horse, I also don't believe it will correct a poor saddle fit nor do I feel it provides any true benefit over any other well fit saddle tree. The one thing that I don't particularly like about the flex trees is that I prefer natural products that are more forgiving in the construction of a saddle. Ralide and neoprene are not my favorite saddle components. Neoprene is a source of extra heat in your saddle and isn't a good choice for any of your tack.
Besides fitting the saddle to you horse, it is also incredibly important to fit the saddle to you. The bars, while designed to distribute weight over the back evenly can only do so if the weight that they are carrying and placed evenly on the bars. There is a trend towards people riding in saddles that are too large for them. Many people do not realize what size saddle they really need. A larger saddle with longer bars is more likely to cause bridging and extend into that area of the loin that should be avoided. If any part of your saddle, extends back over the horse's hips where the hair changes directions it is too long for that horse.
A properly fitted saddle for a the rider should place the rider's weight directly and evenly over the stirrups. You should not be sitting in a recliner with your feet out in front of you. This places pressure on the back of the bars and will sore your horse over his lumbar vertebrae. You should not have more than just a few fingers of space in the area in front of your leg nor should there be more than just a hand's breath behind you at the cantle. Your weight should not be pressed into the back of the cantle but centered over the center of the bars. A good saddle should make your riding and keeping your balance easier. If you have trouble keeping in the center of your saddle, keeping your feet underneath your body or loose stirrups often you may be fighting a saddle that doesn't fit you or is poorly made.
So, having been there and struggled with saddle fit, let me give you some advice. First of all realize that this is a process of trial and error to a certain degree. Just because you have one saddle with "semi-quarter horse bars" doesn't mean another saddle with "semi-quarter horse bars" will fit your horse. Unfortunately there is no uniformity in the measurements used by saddle makers and most custom saddlers will tell you that these measurements have little meaning. Shop around for the best saddle that you can afford. Stick with a quality made tree by a reputable tree maker and a saddle made for years and years of use. Quality materials mean better wearing on the saddle and less incidence of warping of the tree, stretching of the leather or defects in the materials that cause the saddle to have pressure points. You will be much further ahead having one quality saddle that fits several horses than 3 cheaper factory made saddles that don't fit anything really well. Consult a known expert in the field that has experience in saddles and fitting them to horse and rider. Then do your research. Use the tools mentioned above to determine if the saddle is fitting your horse like it is supposed to.
Here are a few other websites I found helpful in my research besides the ones mentioned in the text.