November 2016 - Not So Simple
Written by Kristen Vlietstra
Tuesday, 01 November 2016 03:28
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Gullet width is a critical component of saddle fit.

by Kristen Vlietstra

Like any other manufacturer of athletic equipment, as saddlers gain more detailed knowledge of the dynamic movement of the horse we make improvements, though sometimes with the added challenge of an equestrian culture steeped in tradition.

True saddle fitters put horses first. We listen to riders and work to educate them. We constantly desire and eagerly strive to improve equipment to better accommodate our equine partners.   Over the course of providing and fitting saddles throughout the last 15-plus years, some of the most common questions I have received concern the width of the gullet - the space between the panels. Horse owners and riders often think that if the saddle isn’t touching the bones of the spine it must be wide enough. This old assertion has proven false.

I worked with a horse not long ago, an 8 year old Anglo-Arab gelding with mystery front end lameness. He was never lame on the same leg day to day and would also have some moderately sound days peppered in. Veterinary science could not find anything physically wrong.

Frustrated and nearly defeated, the owner was preparing to retire him. Checking saddle fit would be her last ditch effort before throwing in the towel.

In examining this horse I immediately noted severe muscle tightness through the length of his spine. His back was a rock. I turned his current saddle over to find 1.5” of space in between the panels. I measured his spinal system at 3” wide!  After being fitted with a 4” wide gullet he went from displaying retirement-worthy lameness to working completely sound in a matter of minutes.

Attention to channel width saved this boy’s career. In this article I would like to explain some of the reasons why this is such a critical issue!

When we examine military saddles made over a century ago we find quite a wide space between the panels, which is also often called the channel. However, in looking at the most popular english style saddles designed just two and three decades ago, we discover that some apparent anatomical knowledge must have been lost in translation. Gullet spaces in these mid- to late 20th Century saddles were shockingly narrow!

At their origin, english saddles were designed to clear only the spinous processes. These are the top ridge of vertebrae that you can feel on the typical equine by pressing your fingers deeply along the very center of the back.
It makes sense that no creature would enjoy a weighted and strapped piece of athletic equipment rubbing, bumping or pinching tissue against these bony vertebrae. In decades past, the average english saddle was widest at the wither area, narrowing often severely through to the rear.

Looking at a horse’s skeleton, we see this mirrored. The spinous processes are wider at the start of the withers and become narrower toward the loin. It is obvious why we need to keep the saddle from interfering with the dorsal processes of the spine and thus understandable that many horse owners and riders believe clearing the bony spine alone to be the acceptable standard. However, one must look more deeply at the spine of the horse and surrounding anatomy to understand that this is not the case. 

Muscle Intersection at the Withers

In choosing and fitting a saddle we need to be aware that there are junctions of muscle groups vital to free movement all around the wither area. Two important muscle groups insert and overlap here: The multifidus and semispinalis. The multifidus is a set of highly innervated, deep muscles which lay closely along the spine, stabilizing and supporting the inter-vertebral joints. The semispinalis muscle group joins the base of the neck to the wither and back. A saddle needs to clear this area entirely to allow supple extension and elevation of the neck and shoulder.

Initially neglected in less recent english saddles were also the muscles and ligaments running along the thoracic spine – the portion of the back where ribs attach to vertebrae.

This is all very telling, but there are still finer points to explore in why gullet widths have in general increased recently and why it is so important that they have. Running along the top of the horse’s spinous process is the supraspinous ligament. This same stretch of ligament actually originates at the poll, where it is known as the nuchal ligament. This very important ligament attaches to seven cervical vertebrae in the neck and continues over the withers. Like a street might curve and change in name to confuse you and your GPS, this same ligament is called the supraspinous ligament from the base of the withers to the point of the croup.

This bridge along the top of your horse’s spine represents two-thirds of the ligaments responsible for the stretching of head and neck, along with how the horse’s back is raised and rounded upward or dropped and hollowed. This supraspinous ligament runs directly under the saddle and rider. Naturally, we do not want to interrupt the actions it needs to perform. When the back is raised this ligament system allows the longissimus dorsi (back muscles) to work in a relaxed and free manner while remaining engaged. Understanding how your horse moves makes it easy to also understand that the gullet channel of the saddle must be wide enough to clear this ligament completely.

The next area critical to movement and important to consider for channel width are the multifidus muscles. This segmented muscle group mentioned earlier lies right next to the bones of the spine. Some parts of this group are inserted as far back as the sacrum and as far forward as the base of the neck. They run forward and upward in segments, interlacing and attaching at either the tops or the sides of the dorsal spinous processes, each bunch of fibers terminating a few vertebrae ahead of where they start. This dynamic helps to support and extend the spine.

When these muscles are active laterally they can contract one side of the spine or the other, contributing massively to bend and flexion in the back. This is where careful selection of channel width becomes especially vital. If the saddle is too narrow between the panels it can hamper lateral movement of the multifidus muscles, making the horse very stiff and resistant to bend. This will also cause the horse to have a tendency to hollow and contract the back. Leaving these muscles unrestricted is essential to having a loose, relaxed and swinging gait.  

Saddle Motion

It is clear why space without contact is needed throughout gullet and along the spinal column, but yet another factor must be considered: The inevitable motion of the saddle on the horse’s back.  The amazing equine body moves in many different ways dependent upon gait, direction and changes in elevation just to name a few factors thrown into the mix.

The best place to see this thought in action is at the canter, most dramatically at the canter on a circle. When the horse is cantering – on the right lead for example – the foreleg on the opposite side (left in our example) is slightly dropped. This has absolutely nothing to do with the quality of the rider, the horse or the equipment. Following this motion, a properly fitted saddle will always sit slightly to the left in back. The same principle can be seen as the saddle sits slightly to the right during left lead canter with left bend. Canter is the most valuable gait I use as a saddle fitter to examine saddle straightness.

If the gullet of the saddle is not wide enough, during any kind of bend, especially in the canter, the panel will push against the side of the spine inhibiting the mutifidus muscles. In the worst cases a channel too narrow can interfere with the supraspinous ligament. Both this muscle group and ligament are crucially important for collection and self carriage of the rib cage. We need this suspension system to be free for it to work properly so that our horses are able to move correctly and soundly without restriction. The more educated we are in the biomechanics of the horse, the more we realize the importance of all of these systems. Understandably, keeping these systems healthy and functioning properly goes a long way in preventing back problems such as kissing spines – an issue for another article altogether.

Lastly we need to look at the intervertebral foramina – the spaces through each vertebra which allow nerves, blood vessels and lymphatics to exit the bony canal at each segment. These spaces lie between the arches of each vertebral body and are formed by ventral notches in the front and back of the vertebral arch. A gullet which is too narrow forces pressure on the areas where these vital soft tissue systems exit the spine and can cause a host of issues for the horse, including the ever-elusive mystery lameness. It is extremely important to clear not only the upper ridges of the vertebrae but also the transverse processes at their sides.

I also want to make the point that it is also possible for a gullet channel to be too wide. There are no horses in existence that need 6” of space between their panels. Usually a horse will need anywhere from 2”-4” of space from panel edge to panel edge to achieve good clearance depending on individual conformation. If we go overboard and create saddles that are too wide in the channel, we would be guaranteed to encounter one or more of the following problems:

1)    The saddle will sit down on top of the horse’s spine, negating the gullet’s sole purpose.
2)    The saddle would need to be built up so high in its panels to achieve clearance of the spine that the rider would be sitting miles away from the horse. 
3)    The panel surface area would be so narrow left to right that pressure would not adequately be distributed beneath them.

It is extremely important that backs are measured correctly and matched with appropriate panels. A handful of saddles on the market now actually allow the channel width to be easily adjusted from horse to horse! The most ridiculous arguments ever made in the saddle fit world are any against progress.

No Such Thing as TMI!

From thermography to the recording and mapping of subtle changes in gaits frame by frame using trackable points, all the way to cameras injected directly into muscle, the study of how a horse moves has grown leaps and bounds in recent years.

All of this information and technology allows us as saddle fitters to constantly change the paradigm of what correct saddle fit is so that we can give you the best and most current information. One of the most constantly affirmed principles I’ve observed in action through my experience in saddle fitting is this great importance of channel width.

In more recent years the trend in dressage saddles is returning to this wider gullet style. It is guaranteed that saddle fit will continue to evolve as technology grows. Saddle manufacturers and fitters will follow suit in this evolution. The ultimate goal of a true saddle fitter is to keep both equine and human athletes comfortable, healthy, sound and free to stride toward fulfilling all their performance potential.


Author Kristen Vlietstra has over 15 years of experience in saddle fitting and repair. Her Saddlery Solutions is based in San Jose and serves horses and riders throughout Northern California. She also has 30 years of experience in the horse industry across the western, hunter/jumper, competitive trail, eventing and dressage disciplines. While Kristen has focused mainly on dressage recently, competing through Prix St. Georges, she has a wide range of experience in other facets of the horse world. For more information, visit www.saddlerysolutions.com.