Why? To get them into "the right frame" and hopefully win a prize.
Welcome to the 'get rich quick' scheme of the horse world; large sums of money change hands for well-bred horses who appear ready to win. But in the long run, the lack of foundation in these training methods becomes more obvious at the higher levels and they will not win so many prizes anyway.
In Tug of War, veterinarian Gerd Heuschmann says that a fundamental modification is urgently needed in the way young horses - and riders - are trained. Too many horses, he says, are forced into incorrect positions before their muscles - particularly those of the back and neck - are conditioned enough to take the added weight of a rider and the strain of the intense work they are asked to do.
Adding to this problem is the number of top-quality, purpose bred horses which are seemingly too tolerant of these fast-tracked methods, and so the damaging methods continue.
Dr Heuschmann explains why these non-classical methods are very bad for the horse, and many pictures of the horse's muscular and skeletal system accompany the text to help the reader understand why forced training is detrimental to the horse and its development.
Many photographs illustrate the right way and the wrong way - the "wrong" pictures are very enlightening and in many cases show horses in top-level competition.
In the news recently is the practice of Rollkur (hyperflexion of the neck), with the FEI holding workshops on the topic as part of its welfare initiatives. However, the FEI's position seems to be that the method "is not detrimental if used in a correct manner."
But Dr Heuschmann says that hyperflexion places enormous tension on the upper neck muscles and ligament system, and the back. He says working a horse in this manner will often cause the horse to have a straight, flat back line, with inactive trailing hind legs and little flexion in the haunches.
Horses need time to develop, and unfortunately trainers and riders are not giving them that. Dr Heuschmann believes that a dressage saddle should not be placed on a three-year-old, and the fashion of tight nosebands being used mindlessly should be abolished.
Judges, too, need to be educated about the difference between movements that are natural and those that are artificially forced.
As a veterinarian, Dr Heuschmann says he regularly sees horses showing symptoms that can be traced back to their incorrect training methods. "The biggest mistakes gravely affecting the horse's health and soundness are made at the beginning of its training, that is, during the phase of the horse's so-called 'basic' training."
Tug of War should make all riders stop and think about their horse and how they are being trained. Is what you are doing in your horse's best interest, or your own?
Along with Klaus Balkenhol and other prominent figures in the dressage community, Dr Heuschmann is a founding member of 'Xenophon', an organisation dedicated to "fighting hard against serious mistakes in equestrian sport".