One thing that should become immediately clear is that horses aren't always built to perform the gait for which they are registered and bred. A Missouri Fox Trotting Horse may well be inclined toward the rack or running walk, while a Tennessee Walking Horse may prefer to fox trot. This is true regardless of the animal's breed: Icelandic, Paso Fino, Peruvian Paso, Mountain Horses. . .virtually every kind of gaited horse should be assessed on its individual gait inclinations, and not purchased simply because it's a breed that is 'supposed' to perform this or that particular gait. There's wide genetic variety within each breed. Even Peruvian and Icelandic horses, which have been bred true for hundreds of years, have various strains, or genetic phenotypes, from different regions of their respective countries.
It's also important to point out that while gait is not based solely on registry, it's also not based solely on a horse's conformation. Horses seem to be neurologically wired to perform gaits in a particular fashion. Thus, a horse that is conformed in such a way that it could execute a brilliant rack. . .may be wired toward a hard or stepping pace, or toward a trot. However, if the ability to gait is there, and the animal possesses the appropriate conformation for a particular gait, then it is usually possible to train the horse to perform that gait in a natural, humane fashion.
As a rule, the only time it becomes essential that a horse perform a saddle gait in a particular way is if the horse is to be shown. Those who plan to show their animals are especially responsible, therefore, to purchase animals that are well conformed for their particular show ring gait. Far too often these poor creatures are purchased based on their beauty, personality, trainability, color, or charisma. . .and then have to be 'fixed' to be able to properly perform the desired gait. Forcing a horse to use its body in a manner that is contrary to its natural conformation requires inhumane training practices. It is also detrimental to long term soundness.
Let me give you one simple example, and then we'll allow you to move on. Let's say a person purchases a TWH for show. They have the best intentions: to show only in lite shod classes, and to train using simple riding techniques and humane tack. But it turns out that the horse they've spent their money on has a fairly horizontal arm, limiting its ability to lift in front. Also, its stifle is set a bit low, so it possesses only a slight natural over stride.
Unless the owner is willing to resort to artificial methods and devices, this horse is simply not going to cut it in the show ring. What do you do with such a horse? It likely was more expensive than what you could resell it for, in the trail horse market. But if you resell it to another show family, it's quite certain the horse will be subjected to inhumane training practices, after all. So you either take a financial hit, keep the horse as a family pet, resort to training gimmicks--or sell the horse to someone else who will have to make these same hard choices.
Watch Brenda's conformation demonstrations at the links below!