Gingering

Gingering, or gingering the tail is the practice of making a horse carry its tail high, and to a lesser extent to encourage it to move in a lively fashion, by applying an irritant, such as raw ginger, to its anus or vulva. Historically the process, the purpose of which was often to make an older horse behave like one that was younger, or to temporarily liven up a sick or weakened animal, was known as feaguing (from which the modern term figging derives), and involved a piece of ginger, onion, pepper, tobacco, or a live eel. The modern practice commonly involves a paste product with concentrated gingerol.
For the halter horses in the Arabian and American Saddlebred breeds, high tail carriage and animation are desired traits. However, nearly all horse show sanctioning organizations in the U.S. explicitly forbid gingering and have the authority to disqualify a horse treated in this way. While some areas may be less than rigorous about enforcing the rule, tests such as "ginger swabbing" may be done to detect the presence of ginger in the anus. While it is not entirely reliable, concerns of being detected by anal tests has led to some horse handlers placing the irritant in the vagina if the horse is a mare. A modern veterinary dictionary notes that vaginal placement is more effective than anal insertion, because the irritant is likely to remain in place longer, and concludes gingering "would be considered to be an act of cruelty in any civilized community".