Saddle Fitting the Thoroughbred Horse

The Thoroughbred horse,

especially the off the track racehorse can be one of the more daunting breeds to saddle correctly. Most people take one look at their sharp, high withers, the deep shoulders, and they know, without a proper fit, the rest of the back will take a real beating. Add to this the knowledge that most thoroughbreds are highly sensitive individuals and you understand why, here at ThinLine, they are some of our favorite equines to saddle fit.  You may also be interested in our guide to fitting western saddles.

What is ThinLine?

ThinLine is a thin, shock-absorbing non-slip breathable foam.  It will improve equine comfort to such a degree thoroughbreds will “settle” and become more relaxed, we offer a money-back guarantee to this promise.

Where is the ThinLine?

It is sewn onto the panel of our saddle pads. Here you can see the ThinLine foam on top of an english half pad and a western cotton liner pad. And you can also see the selection of saddle fitting shims, made of the same comfort foam.

English Booster Stacked Shim Design EnglishPad web7304 Cotton Liner Close up girl WEB


Thoroughbred horse saddle fitting solutions are easy and with ThinLine saddle fit inserts you will double your results by saddle fitting with the best therapeutic materials.

English Booster Stacked Shim Design EnglishPad webWestern Booster Stacked Shim Design3 web








  • High Withers: Add Front shims to any pad.
  • Hollow or Sway  Backs: Add bridging shims.
  • Rider Balance: Adding a pair of shims to one side can fix balance issues.
  • Saddle Balance: Front or rear Shims, depending on your issue.
  • Saddle Slippage: Generally no shims are needed, the ThinLine Pad alone will solve this.
  • Saddle Pad Slippage: Generally your tree is too wide. Add a Booster Shim.
  • Equine or Rider Back Soreness: No shims needed, ThinLine protects both.
  • Equine Asymmetry: place both of the pair of shims on the hollow side.
  • Kissing Spine Relief: Add a Booster Shim to any ThinLine pad.
  • Treeless Saddle Pad Comfort: Add a Booster Shim to any ThinLine Pad.


Stacking and layering saddle fitting shims.

  • ThinLine pads accept up to three 1/4 inch saddle fit shims in a single location.
  • Layering sets of shims will create an even transition for major saddle fit issues. Shims may also be cut with a pair of scissors for custom work.
  • Full shims are available in two thicknesses. When placed under the panel of ThinLine already on your pad you double or triple your ThinLine protection.
custom saddle fit shims inserts
Layering sets of shims

How to order Saddle Fitting Shims.

Select a ThinLine Saddle Pad.  You will see the shim options just under the product.

Western Saddle Fitting Shim Poster

The entire area under the ThinLine portion accepts up to 3 sets of 1/4 inch shims in one area. There are no “pockets”, allowing you to place stack and create gradual transitions between shims.

Saddle fitting with this with shock-absorbing foam provides balance, comfort, and protection for horse and rider.   Now you simply need to find the pad that fits the dimensions of your saddle and the style that fits your life.  Read on if you need more detailed saddle fitting information, or,

shop now button

Saddle Fitting the Thoroughbred Horse with Master Saddler Cordia Person.

“The Thoroughbred horse, especially the off the track racehorse, can be one of the more daunting breeds to saddle correctly. Most people take one look at their sharp, high withers, the deep shoulders, and they know, without a proper fit, the rest of the back will take a real beating. 

I have found ThinLine has an easy solution for those high withers, slab sides, and well-sprung rib cages! Equally important is extraordinary protection.  Thoroughbreds are historically sensitive animals.  I repeatedly see overnight transformations from unhappy hollow backed going to happy collected horses.

Ex Racehorses often come off the track with their share of issues.  But with this product, they can be dealt with relatively inexpensively and it does not take a great deal of time.

I primarily use the Trifecta Half Pad with a set of 1/4 inch front shims. ” (Cordia Person, Society of Master Saddlers)”.

English Booster Stacked Shim Design EnglishPad web Western Booster Stacked Shim Design3 web

Adjustable Saddle Pads With Open Pockets give you the freedom to Shim where you need it most.

The ThinLine shimming system allowing riders and saddle fitters to create a custom fit with shock-absorbing therapeutic shims.  Shims are easily inserted or removed and stay in place during riding and washing. Use up to three pairs of 1/4 inch shims in the same location.

70 booster shim full WEB

Western felt liner booster shim






Underneath the ThinLine layer on all our pads is a pocket to insert shims. If you need help with minor saddle fit adjustments, purchase your saddle pad and use it alone or add shims. Either way, your saddle will fit better and your horse will use his back better and stay sounder longer.  Shims are made of the same therapeutic ThinLine material. Once you place a Thinline saddle pad in your shopping cart you will see below your cart, Add shims to the pad in my cart. Simply add the shims you need.

Available Saddle Fitting Shims:

  • Full  Shim: A pair of shims running the full panel will create ThinLine Plus (1/4 inch) Thickness for intense protection.
  • Front Shims: Provide lift in the wither area and are available in two thicknesses, sold in pairs.
  • Bridging Shims: Fill in gaps over the top line. Available in two thicknesses, sold in pairs.
  • Rear Shims: Lift the cantle of the saddle for perfect balance. Available in two thicknesses, sold in pairs.


shop now button

Pictured above Sieren Peterson riding Navarre

Master Saddler Cordia Person on Saddle Fitting the Thoroughbred Horse.

“When I first met Navarre, an off the track TB, he was in a gorgeous saddle sadly two tree sizes too small. He had a huge swooping wither and severe muscle wastage under the too-narrow saddle points. When I reached inside the channel of the saddle, the stirrup bars were like vises against the long muscles of his back. Palpation had to be very gentle as he came close to dropping to his knees under any pressure. I showed his rider how to do the essential belly lift, drawing a thumb along the centerline of his belly and told her every chance she got, to raise his back. The 30 cm saddle was replaced with a 34 cm wide saddle tree and a ThinLine sheepskin saddle pad.

If you are not familiar with ThinLine’s thoroughbred horse tack, this product is my saddle fitting dream-come-true saddle pad. I have tested tons of different pads. Until I put ThinLine to a two-week test I had never found anything that did what I was looking for. ThinLine asked me to try their pads for two weeks. I rode my two correctly saddled stallions one day with the ThinLine, the next without. At the end of that time, I called Elaine Lockhead, owner of ThinLine and said, sign me up!

With the ThinLine, my horses’ gaits were larger and had more swing. My aids were more like thoughts than actions. And most important of all was the feeling like two hands reaching up into the saddle, pressing my seat bones upward as my guys lifted their backs when the ThinLine was part of the saddling equation.

Why ThinLine works is its unique construction

— open — cell foam which moves shock, weight, and heat laterally. Beginning as a liquid, microscopic cells are poured into a mold, then polarized so each cell lies end to end creating a tunnel. Another layer is poured on top and polarized in a new direction. In each ThinLine pad, this process is repeated hundreds of times, creating a honeycomb matrix that is breathable as well. ThinLine products also carry tensile strength so that pressure is evenly distributed: filling in hollow points while relieving pressure points AT THE SAME TIME!


When I check most Western and English “corrective” pads, I pinch the top and bottom layers. Most are lucky if I don’t feel my fingertips, even when these pads at an inch thick. ThinLine never bottoms out. I think I was the first Society of Master Saddlers Qualified Saddle Fitters to endorse ThinLine’s thoroughbred horse tack and they have been my mainstay problem solver ever since.

What I have found with the Thoroughbred owners I’ve worked with is that they all seem to have read Mary Wanless’ book, ‘For the Good of the Horse.” In this book, Mary reports about a study done in England where they tested just how much a horse’s back would grow, given the chance. In the study, some of the horses increased their back width seven-fold! This same study discovered what happens when a saddle that is too small is not changed. Just like Navarre, the muscling hits the tree, then backs off. If this goes on too long, the backing off becomes muscle wastage and then the next thing you know, soundness issues start popping up. Little wonder – you’d be unsound too if someone made you gallop and jump in shoes two or three sizes too small.

With Navarre, we had a more than a happy ending. Two days after we changed his saddling and added the ThinLine Correction Sheepskin saddle pad, he was at Trot Brook, our largest Event in MN. He placed fifth in a large field with Sieren Peterson on board. But even more gratifying, when I rechecked his saddle a month later, his back was not only healed, but turning into a gorgeous field of new muscle.

High Withers

If you have a Thoroughbred in your life, don’t let their withers lead you into doing the wrong thing. When evaluating a saddle, do so without any pads or a girth. Check the channel. All ThinLine pads except the basics have a spine free channel and pockets for adding ThinLine saddle fit shims. And lastly, reach under the stirrup bars. This is an area that doesn’t get checked frequently enough.

There are many very reasonably priced saddles that work well with the TB back, but I would only use a wool flocked saddle with them as the structure of this breed is close to the skin and thus easily sored by incorrect fit. When not able to turn to a more expensive custom saddle, my favorite combination always includes a wider, rather than a narrower tree and a ThinLine pad which can be shimmed to allow for the muscle that will appear with this combination.

If saddling your TB with a Western saddle, I highly recommend that you avail yourself the Steel “Fit to Be Seen” system. This series of fiberglass forms, made up in the shape of the most popular bars, is the only good way to really see the impact of a Western saddle on the back and wither. While doing this, it is very important to make sure the horse’s back is raised. If the horse is in pain and the back is dropped, you could end up saddling the problem rather than the solution. With all my new Western Dressage and Western Reining Riders, I recommend the Western Dressage liner or the Felt pads. Again all take shims allowing for saddle adjustment while the horses develop better back muscles.

If I can be of any help answering your questions, you can contact me through my website,, or call at 651-462-5654. Ride happy!

Cordia Pearson, SMS


Saddle Fitting the Thoroughbred Horse