Dressage competitions require a prescribed series of movements within a standard arena, and are steeped in tradition. As McLean and McGreevy  describe it, “… New Age trainers and so-called horse whisperers [use] anthropocentric language and euphemisms to camouflage chasing and consequent fearful responses in the round pen … Using fear in learning programs is something that modern pedagogy has totally abandoned, yet it still occurs in horse training.”
In some countries several abusive practices are aimed at achieving specific dressage gaits and postures. Tail carriage may be altered by cutting tail tendons, injecting rectal (anal) irritants, or injecting alcohol to deaden nerves. The purpose may be to elevate the tails of show horses, to cause them to hang limply, or to prevent agitated tail movements during performances, which leads to the deduction of points. However, this prevents natural tail functioning, which is important to repel flies and biting insects, and to communicate mental and physiological states (e.g. being in heat) to other horses .
1. McLean AN and McGreevy PD. (2010). Ethical equitation: capping the price horses pay for human glory. J Vet Behav: Clin Applications Res, 5(4), 203-209.
2. American Veterinary Medical Association (AVMA) Animal Welfare Division. (2012). Literature review on the welfare implications of horse tail modifications. Schaumburg, IL: AVMA.