The International Equestrian Federation (FEI) has announced that all human and equine doping samples taken during the Rio 2016 Paralympic Games have returned negative.
That means there has now been back-to-back clean Paralympic Games for Para-equestrian sport, with the Rio 2016 results following the same outcome at London 2012.
This follows the recent announcement by the FEI of a clean Olympic Games in both 2012 and 2016.
A total of 38 equine samples were taken during the Paralympics and sent for testing at the FEI Central Laboratory in English town Newmarket, one of the five FEI approved laboratories worldwide.
Human testing, which is conducted by the International Paralympic Committee (IPC) during the Paralympic Games, also returned 100 per cent negative results for the equestrian athletes sampled.
"We are very proud of our efforts on clean sport at the FEI, working closely with our National Federations and all our athletes," said FEI President Ingmar De Vos.
"Everyone involved should be proud of our clean Olympic and Paralympic Games record in 2016 and 2012.
"We actively educated our athletes about the importance of clean sport before both Games in Rio and this is proof that our educational campaign is working."
Six days of high quality competition at the Rio 2016 Paralympics saw Britain continue its unbeaten Paralympic record, with another team gold.
Team members Sophie Christensen and Natasha Baker became triple gold medallists when successfully defending their London 2012 dressage titles, while Lee Pearson won his 11th Paralympic title.
Belgium’s London 2012 champion Michèle George also successfully defended her individual freestyle gold, with Ann Cathrin Lübbe of Norway topping the grade III individual championship.
The Games also saw Uruguay field a Para-equestrian athlete for the first time - Alfosina Maldonado - and host nation Brazil won bronze in the individual freestyle grade 1a thanks to Sergio Olivia.
This was the first Paralympic equestrian medal for Brazil since 2008.