In some cases, the addition of stirrups without a supporting tree place pressure on the horse's spinous processes, potentially causing damage. Fitting A saddle, regardless of type, must fit both horse and rider. Saddle fitting is an art and in ideal circumstances is performed by a professional saddlemaker or saddle fitter. Custom-made saddles designed for an individual horse and rider will fit the best, but are also the most expensive. However, many manufactured saddles provide a decent fit if properly selected, and some minor adjustments can be made. Horse The definition of a fitting saddle is still controversial; however, there is a general rule for fitting that no damage should occur to the horse's skin and no injury should be presented to any muscular or neural tissues beneath the saddle. Width of the saddle is the primary means by which a saddle is measured and fitted to a horse, though length of tree and proper balance must also be considered. The gullet of a saddle must clear the withers of the horse, but yet must not be so narrow as to pinch the horse's back. The tree must be positioned so that the tree points (English) or bars (Western) do not interfere with the movement of the horse's shoulder. The seat of the saddle must be positioned so that the rider, when riding correctly, is placed over the horse's center of balance. The bars of the saddle must not be so long that they place pressure beyond the last rib of the horse. A too-short tree alone does not usually create a problem, as shorter trees are most often on saddles made for children, though a short tree with an unbalanced adult rider may create abnormal pressure points. While a horse's back can be measured for size and shape, the saddle must be tried on the individual animal to assure proper fit. Saddle blankets or pads can provide assistance to correct minor fit problems, but no amount of padding can compensate for a poor-fitting saddle. The common problems associated with saddle fitting problems are: bridging, ill-fitting headplates and incorrect stuffing of the panels. One saddle simply cannot fit all animals. Nor will a saddle fit even the same horse forever without adjustments. As a horse advances in conditioning, age, and training, the back muscles and even the underlying skeletal structures change to some degree. Thus, particularly with English saddles, a