One of my instructors once mentioned that a horse was like an airplane on take off. First, the nose of the airplane lifts (the front end of the horse) and then the rear pushes it forwards as it takes off. This mental image has stuck with me in all of my riding. The power or impulsion from the horse comes from the hind end through to the front end. The back, then, is the connection piece between the engine of the horse and the steering. Below we will show you how the back then affects the horse’s performance.
If you have the time to go out to the barn with a measuring tape, I recommend measuring the length of the horse’s entire body (from the point of the shoulder to the point of the buttocks). Record that number, then measure the length of the back from the point of the withers to the point of the croup or the LS joint (the point where the pelvis meets the spine, just behind the saddle). Then plug the numbers into the following formula:
Back Length/Body Length x 100 = Percentage of the Body that is the Back
Once you have that measurement, the general rule is that if the back is:
- less than 44% it is considered short
- 45%-49% it is medium, and
- 49+% it is long.
What does this mean for your horse?
A horse with a long back will be easier to steer, will jump flat but have a harder time collecting because his legs will have to come much farther underneath himself to take on more of the weight. A horse with a longer back, too, will be more likely to develop a sway back.
A horse with a medium back will have to be trained to use it properly. He is inbetween, he won’t have as much difficulty engaging as a horse with a long back, but it will also not be as easy as for a horse with a short back.
A horse with a short back will not only have a stronger lumbar section (a very long stick is easier to bend then a very short one), it will be easier for him to engage and pivot around his hindend.
Another measurement to take into consideration when analyzing the back is the ratio between the thoracic vertebrae and the lumbar vertebrae. Ideally, your horse will have a 70:30 thoracic:lumbar ratio.
The proper way to measure this, again, if you have a measuring tape is to measure the distance between the point of the withers and where the last rib joints the vertebrae. Generally speaking you should be able to follow the last rib from the side of the horse upwards. Where it hides underneath muscle and fat, it generally angles back towards the head of the horse. Then you would take the measurement from the last rib to the LS joint. Divide both numbers by the total back length you took in the first measurements and multiply them by 100. This will give you the percentage of the back that is thoracic, or lumbar, respectively.
If you do not have the time or measuring tape to take such exacting measurements, the old fashioned method of measuring the length of the lumbar is to place your hand between the last rib and the point of the hip. You want this to be as tight as possible, without the hip actually hitting the rib. Ideally you want no more than 8” in this space.
So start to look at horses closely. Notice their backs, the ratios, if they’re appealing to the eye, if they have swayed or roached backs, why that is, etc and if you have the time, run out to the barn with a measuring tape and have some fun!