The rider sits on the horse’s back and is carried forward. But the horse’s back is not designed to carry weight, and that is why so many horses travel with their backs hollow and tense. This is where I tell you to read a certain one hundred page book on skeletal, ligamental and muscular anatomy, center of gravity, the ‘ring of muscles’, how the horse must be ridden to counter this physical weakness, why it so often goes wrong, blah, blah, blah. The truth is if everyone knew that we wouldn’t be ‘here’ talking about something as simple as back length. Someday we’ll tackle that topic, but not today.

For now it’s good enough to know that a long back in a horse is a fault.   It lacks longitudinal strength and often sags under the weight of a rider, creating a ‘leg mover’ that certainly can give a smoother ride, but only at the expense of the horse.  Prime examples of leg movers are gaited horses that tense and hollow their backs to be able to move their legs in any number of timed sequences, as opposed to your ‘back mover’, the Dressage horse, that swings freely through the loin and back.  This latter requires a rider to have a supple lower back that follows and absorbs this movement to prevent being launched out of the saddle.

Additionally on the subject of longitudinal strength; without it the horse cannot easily maintain engagement.

A long backed horse often presents the rider with the additional challenge of trying to keep the horse straight from dock to poll.  Don’t, however, confuse that with lateral flexibility.  Indeed, a shorter backed horse is often more laterally flexible than its long-backed counterpart.  I will address that in an additional article (2b) in this series.

An excessively short back is also a fault in a horse.  Such a configuration doesn’t allow for enough room for a saddle to be placed, as well, sets the rider’s weight on the loin rather than on the ribcage.  It’s never a good idea to ride a horse from its loin; the weakest portion of an already weak structure.

• A long back: >50%
• A medium back: 45-49% (Note: 45% is considered ‘ideal’ for a riding horse; the ‘perfect’ length to provide lateral flexibility and longitudinal strength)
• A short back: < 45%

To determine back length we measure the horse’s body length and divide that number into the back length number to arrive at a percentage. 

• Body length is measured from point of shoulder to point of buttock. 
• Back length is measured from highest point of wither to lumbo-sacral joint.

Here is our trusty skeleton horse with the points marked in red.  The highest point of wither is usually thoracic vertebrae four (T4) and the lumbo-sacral (LS) joint is located between lumbar vertebrae six (L6) and sacral vertebrae one (S1).  I’ve added an extra dot marking the highest point of croup (sacral tuber – top point of the pelvic bone) to help establish the location of the LS joint since it can’t actually be ‘seen’ in a photo; residing 2-4 inches below the surface of the skin. 

The best way to locate the LS joint on a horse is to palpate the horse’s back.  As you move along the length of the back you can feel the individual spines of the vertebrae, then you’ll hit a ‘mushy’ spot and finally vertebrae spines again.  Below that ‘mushy’ spot is the LS joint.  For article purposes, we’ll use the highest point of croup (which is located behind the LS joint) to help us find the LS joint in photographs.

The LS joint is the most important trait to discuss in horses in terms of athletic potential and movement.  The entire hindquarter of the horse pivots on this joint and its location relative to the horse’s point of hip is instrumental to a horse’s ability to engage and collect.

I’ve added more dots to our six candidates and it’s time to measure back lengths.  The LS joint is marked in a different color and though I’ve placed that mark at the skin level of the horse for measuring sake, remember that it resides 2-4 inches below the skin surface.

Horse #1 – 10yr old QH Stallion

Take a look at him unmarked.  Where do you see the points and how does his back length look to your eye?  Imagining a saddle on the horse and seeing how much space between the back of it and the start of the hip is sometimes helpful.  If there’s a lot of room, chances are the back is long.  If no room, then the back is likely short.

This horse has a back length of approximately 41.5%.  That falls clearly in the short back range, giving this horse a high degree of longitudinal strength.  Did you imagine a Western saddle on him and where the skirt might come to?

Horse #2 – QH Gelding

How does this horse’s back length compare?  Does it look longer or shorter?

This one measures almost 42.5%, so a full percentile longer but still falling in the short range and possessing a high degree of longitudinal strength. 

Start to take notice of the relationship of the highest point of croup, point of hip and LS joint, and how they differ for every horse.

Horse #3 – 4yr old QH

Like the first time around, when it was difficult to spot his point of shoulder, it’s equally as difficult to spot this horse’s highest point of wither.  He has lower withers in general, which is not a fault and different than ‘mutton’ withers, which is a serious fault in the horse. 

How does his back length look?

If you thought this one looked longer than the first two, then you get a gold star.  This horse is approximately 48% falling in the medium back length category.

Horse #4 – Arabian Stallion

Here we see a set of prominent withers.  In this case they are also ‘camel withers’.  Though difficult to detect because of the mane and photo background, look closely.  Follow the top line of the mane and you’ll see a significant dip in front of the wither and then the wither drops off abruptly.   A dip in front of the withers can indicate a few different things, so not all horses with a dip there (and an abrupt ending) have camel withers.  Let’s compare horse #2, our roan QH.  The dip in front of his withers is easily gotten rid of with good riding and training, which would significantly change his neck musculature and fill in that dip.  Our Arabian stallion, though, already has way better neck musculature (mostly because it’s a stallion’s way to arch and telescope their neck to get the chicks) and still a big dip.  There is no amount of correct riding or training that will get rid of it.  Camel withers do not function as well as better constructed withers; that as a ‘fulcrum’.

Scroll back to the skeleton horse for a moment and look at the ‘spines of the wither vertebrae’ that make up the withers.  Those spines vary in length for every horse.  Thoroughbreds generally have very long spines compared to Quarter Horses.

Back to our Arabian stallion; how does his back look?

He too falls into the short back category at almost 43.5%.

Horse #5 – TB Gelding

Now that you’ve seen three short backs and one medium, has your eye gotten good enough to guess where this horse’s back length falls?  The mane and the background of this photo make it hard to see that highest point of wither.

If you guessed the longest back of all so far, but still falling in the medium range at 49%, then you were right.  What is most significant, though, is the placement of the LS joint.  Remember this horse had the shortest pelvic length of the group, representing the least power potential by falling in the poor category.  But I also said the horse had two ‘saving graces’, one of them being exceptional location of the LS joint, and earlier in this article I stated that the LS joint was the most important trait to discuss when talking about athletic potential and movement . 

Here we clearly see that the LS joint is located the furthest in front of the point of hip of any horse thus far.  That is most advantageous for ANY horse, ‘adding’ length to the hip and thus power potential.  In this case that poor length of hip is moved into the adequate/average category.  Is it then possible that the LS joint placed ‘behind’ the point of hip (such as seen with our roan QH) might ‘subtract’ length and thus power potential from the hip? (Rhetorical question)  Additionally and even more importantly, an LS joint placed in front of the point of hip makes engagement, as a whole, easier to achieve.

Horse #6 – Paint Mare

Last chance to test your eye on the horse with the hardest point of wither to identify.  I’m not entirely convinced I’ve got it right.

As it’s marked this horse falls long with a back of 50%.  If I’m off at all, it’s a touch to the long side, but either way we’re looking at a back as long as we ever want to see on a horse, and we’d really prefer it to be shorter.

There is one more thing I’d like to point out concerning back strength.  The further withers carry into the back, and the gentler they taper off into the back, the more strength they add to a back.  Of this group, our TB has the nicest set of withers that gently taper off the greatest distance into the back, adding strength.

It’s time now to go out into your barn and palpate your horses’ backs and find the LS joint and its relationship to the point of hip.  Look at their backs and guess their lengths, then measure to see how close you were with your estimations.  Look at their withers, are they prominent and drop off abruptly, or are they lower and flow smoothly into the back, or some combination.