|Normal Horse||Mutton-Withered Horse|
The side view of your horse should have a small ridge where the withers are. If you horse just has a gradual slope toward the rear without any shoulder definition, you have a mutton-withered horse. The thocratic vertebrae which usually create extra shoulder definition are shorter than normal. This is most common in American Quarter horses, ponies, and arabians. Your horse will probably have less of a range of motion because of the mutton withers, but will perform as well as other horses.
The problem that mutton withers create in saddle fitting is that most saddles are built with normal withers in mind. The withers help keep the saddle in place, creating a ridge.