Athina Onassis de Miranda’s horse, AD Camille Z, has been euthanized following a fall while competing in the Credit Suisse Grand Prix at the Geneva CSIO on Dec. 11.

The 11-year-old gray Zangersheide mare suffered a fracture in the fall over an oxer on course. De Miranda also fell, but was uninjured. Camille was sedated and transported to a veterinary clinic, but veterinarians decided with de Miranda and her husband, Brazilian show jumper Alvaro de Miranda, that euthanization was the only option.

Alvaro “Doda” de Mirando posted a tribute to Camille on Instagram which read: “Thank you AD Camille from the bottom of our hearts for being “just the BEST.” We are proud to had you with us and was unbelievable how many good moments you and Athina had together. Rest in peace and be sure we will be strong enough to keep going and YOU will always be in our hearts. #ripadcamillez”

Camille and Athina represented Greece at the 2014 Alltech FEI World Equestrian Games (France) and at the 2013 European Championships (Denmark). In 2014, they were sixth in the Longines Global Champions Tour of London and fifth in the Longines GCT of Chantilly (France). The were also third in the $500,000 FTI Consulting Finale Grand Prix in Wellington, Fla., in 2013. Athina bought the mare in 2012; Spanish rider Marta Fernandez Andrade had competed her at the two-star grand prix level.