Pretty much everyone riding is aware that trees come in narrow, medium, or wide, but did you know that those designations can refer both to the width of the tree (more about that in Saddle Fit Tip #9) and to the angle of the tree? If a saddle fitter tells you that your saddle is a “wide narrow,” this means that you have a saddle with a wide tree width and a narrow tree angle.

In previous Saddle Fit Tips, I discussed why it is so important that the saddle stay behind the horse’s shoulder. If it does not, and constantly moves forward, the tree points of the saddle will drive into the horse’s shoulders, first producing a buildup of scar tissue on his scapula, and then chipping away cartilage and bone. This is irreversible long-term damage, and can lead to persistent unsoundness and the premature retirement of the horse.

What does the tree angle have to do with all of this? In order to avoid this kind of damage, it is crucial that the angle of the tree be adjusted to match the angle of the horse’s shoulder. Think of two sliding doors. If they are properly aligned, one will slide freely past the other. But if they are not, one will jam into the other. It is the same with your horse’s shoulders and the angle of his saddle’s tree. As the horse moves, his shoulder rotates upward and backwards, as was discussed in Saddle Fit Tip #2. If your saddle’s tree angle does not match the angle of your horse’s shoulder, his shoulders will be unable to rotate freely under the saddle, compromising his movement, sometimes severely. At the very least, a saddle with a tree angle that is not correctly adjusted is extremely uncomfortable for your horse. At worst, it can lead to irreversible long-term damage.

How do saddle fitters determine if the tree angle of your horse’s saddle matches the angle of his shoulder? They can use the Sprenger gauge to measure the horse’s shoulder angle. They put the Sprenger behind the shoulder blade, and set it so that the upper arm of the device is parallel to the angle of the horse’s scapula. Then they adjust the tree of the saddle so that the tree angle matches that of the horse’s shoulder. (however, in its most basic form, most saddle fitters use the flexible ruler to determine shape over the withers, which is somewhat remedial if you really want to get the angle degree right).

How can you tell if the tree angle on your saddle is correct for your horse? Put the saddle on your horse without a saddle pad. Then check if the angle of the piping on the saddle matches the angle of your horse’s shoulder. If it does, the angle of your saddle’s tree is correctly adjusted for your horse.

If you’re still uncertain if the angle of your saddle’s tree is correct for your horse, observe his behavior under saddle. If the tree angle is too wide, there may be clearance on the top of your horse’s withers, but the saddle will pinch the sides of his withers. It will also hit the reflex point (cranial nerve 11) that restricts movement in his shoulders and makes him unwilling or unable to move freely forward. The horse will raise his head or hollow his back, or exhibit other forms of resistance until the reflex point/ nerve becomes numb. If your horse behaves in this manner, it may be because the tree angle of your saddle is incorrect for him. It is important to understand that your horse doesn’t want to be bad, but if the saddle keeps hitting that reflex point, he almost has no choice: he cannot engage the muscles you’re asking him to engage. He cannot do what you’re asking him to do, and this can lead to unnecessary fights between horse and rider.

One of the most common ‘excuses’ I hear is that “I have to ride him for a while and warm him up before he’ll listen”. What is really happening here is unfortunately that the horse is being ridden until he becomes numb to the pain! So maybe here is the reason why – and even though a saddle may look like it fits while the horse is standing still, the angle may actually change when he begins to move! (which is something I’ll go into in a future Saddle Fit Tip in more detail as well – dynamic fit!)