Saddle fit was a hot topic at the 2020 virtual American Association of Equine Practitioners Convention, with many discussions of interest to equine professionals.
Examine your horse’s back after exercise. A normal back with a good-fitting saddle should have sweat in a uniform pattern. If the tree points are too tight, there is often less sweat on the back in the forward portion beneath the saddle, and this tends to be mirrored by dry spots on the pad. Too much pressure in the surrounding region of the sweat gland causes decreased blood circulation that interferes with normal function of the sweat glands.
Transient nodules might develop at the twist around thoracic vertebrae 13-14 due to a narrow gullet or abnormal movement of the back of the saddle. Normally, when looking at a horse from behind, there is minimal side-to-side oscillation of the saddle. If the saddle slips or has an abnormal range of oscillations, this brings the gullet closer to the dorsal midline, with the result that nodules of edema or fibrosis develop from the pressure.
It often helps to compare saddle movement with and without a rider. A saddle that slips to one side might do so because of asymmetrical flocking or a horse’s back shape.
Another significant reason for slippage of the saddle is from hindlimb lameness that modifies movement of the axial skeleton. Sue Dyson, MA, VetMB, PhD, from Britain, noted during the saddle fit discussion at the Convention that 87% of the time in a horse with hindlimb lameness, the saddle will slip to the side, and in particular to the side of the lame leg. (In 13%, the saddle slips to the side of the good or better leg.)
If the lameness is abolished with diagnostic analgesia (nerve blocks), saddle slip markedly decreases or might change to the other side if the opposite hind leg is also lame.
Slippage is more obvious on a circle than a straight line. A saddle slipping due to lameness can cause a rider to sit crooked. It is important to note that saddle slip is not always caused by a crooked rider.
During rising trot, the saddle should sit flat. With a jumping horse, if the back of the saddle rises over jumps, it can create abnormal pressure as the horse lands.
Adjustable tree saddles can be useful, especially as horse's back shape changes. Adjustments of an adjustable head plate only apply to the front of the saddle and have no function for the back of the saddle. If the angle of the rails is wrong, adjusting the head plate won’t help.