Auxiliary reins are commonly used for the training of riders and horses as well as in daily training. They are often criticized when used incorrectly, as they will not help and can harm the horse by causing overwork, accidents, and injuries, which harm the horse in the long term. They also often conceal causal rider problems while trying to achieve quick success. The aim of this paper was to investigate, with an online horse-owner questionnaire, which and how often auxiliary reins were used and whether they were used appropriately. Only participants who were currently using auxiliary reins were selected. Consequently, 823 participants were questioned, of which 362 were currently using auxiliary reins at least every two weeks. Auxiliary reins were mainly used according to their discipline: the running side rein was the most popular when working from the ground and the sliding ring martingale was the most popular for ridden equestrian activities. Most of the test subjects only attached the auxiliary reins after the warm-up phase, but half of the participants did not change them during the entire training session. Most participants (75%) could at least identify what the correct head position of the horse should look like. However, there were still too many (50%) who adjusted their horse too tightly and did not change anything at that time despite the related breathing problems. The study found that most participants used the reins responsibly, but there is still a need for clarification and information relating to the functions of the different auxiliary reins among horse owners.
