Zara Tindall has paid an emotional tribute to her world championship-winning horse Toytown, who has had to be put down.
The Queen's granddaughter said she was "heartbroken" to tell the world "the most incredible athlete with the biggest heart", who had been retired from competing, died on Tuesday morning.
She rode the chestnut gelding to an individual three-day eventing gold medal at the World Equestrian Games in Germany in 2006, which followed the pair winning individual and team European eventing titles in 2005.
They won another European team gold in 2007.
Zara said in a statement: "I'm heartbroken to say that yesterday morning I had to say goodbye to my greatest friend and horse of a lifetime, Toytown. He was the most incredible athlete with the biggest heart, European and World champion back to back.
"He made my career and I couldn't be more grateful to him for the amazing times we had together. He was a huge part of my family, an amazing animal and a true champion.
"I will miss you forever."
A spokeswoman for Mrs Tindall said Toytown, thought to be 25 years old, was put down for medical reasons.
Spotted as a seven-year-old by Zara's' father Captain Mark Phillips, Toytown quickly confirmed his rich potential by finishing second at Burghley in 2003 behind Pippa Funnell and Primmore's Pride.
A leg injury ruled the horse out of the 2004 Olympics in Athens, but a successful period was to follow with World and European titles won with Zara.
The horse's final Great Britain appearance came at Pratoni in Italy during the 2007 European Championships, helping the team secure another gold.
Toytown missed out on the 2008 Olympics due to another injury and three years later he was retired from competing after being paraded in the arena at the Festival of British Eventing at Gatcombe Park, the Gloucestershire estate where Zara's mother the Princess Royal lives.