After months of legal battles, the German Equestrian Federation (FN) has issued a six-month suspension of German dressage rider Isabell Werth for use of prohibited substances.

In June 2012, Werth’s 11-year-old Rhinelander gelding El Santo tested positive for cimetidine, a prohibited substance in the rules of the FN, at a national competition, an FN representative said. Cimetidine is a drug used for treating or preventing digestive tract ulcers.

At the time, the gelding’s stall neighbor, 16-year-old Hanoverian Warum Nicht FRH, was being treated with cimetidine to relieve secondary effects of pain medications following a fracture, according to Werth’s representative. Werth suspected that El Santo might have accidentally consumed some of the medication due to close proximity of the stalls, possibly through a failed water pipe system. Studies have proven that accidental contamination of stall neighbors is possible, though not necessarily through water pipes.

While the FN tribunal has agreed that El Santo was likely to have been accidentally contaminated, perhaps through the bars of the stalls and not the water system, the federation still declared Werth responsible. The unintentional contamination was a result of “breach of duty of care” in barn management, the FN ruled