A traditional saddle tree acts as a foundation for the rest of the saddle structure and distributes the rider's weight. This weight distribution helps prevent injury to the horse's spine. A treeless saddle instead uses thick pads or panels of foam, leather or other soft materials to cushion the horse's back.
Advantages for the Horse
The primary advantage of a treeless saddle for your horse is that the lack of a rigid tree allows your horse a full range of movement, especially through the shoulders. A treeless saddle can also fit horses with conformation that would make a traditional saddle fit improperly. Examples include horses with high withers or uneven shoulders.
Advantages for the Rider
The treeless saddle's ability to fit horses with different sizes and conformational attributes makes it easier for you to fit the saddle to your horse. A treeless saddle also allows you to make closer contact with your horse and to feel the horse's movement. The more you ride in a treeless saddle, the more it will conform to you and your horse's back, making it more comfortable the longer you use it.
Disadvantages for the Horse
A treeless saddle may put pressure on the horse's spine, particularly if a heavy rider uses it. Some treeless saddles are not suitable for heavy riders, while others may need extra pads to prevent pressure on the horse's spine. Even though there is no rigid tree, you still have to be careful fitting these saddles to your horse to prevent discomfort or injury.
Disadvantages for the Rider
A rider using a treeless saddle must have good balance and a firm seat because the horse has more contact with the rider. This closer contact can cause confusion in the horse if it misinterprets an unbalanced rider's movement as a signal. A treeless saddle can also cause a rider to sit wider than a conventional saddle, which may cause discomfort for some riders.