Australian equestrian stalwart Megan Jones says retiring her beloved horse from eventing competition was a gut-wrenching decision. 

Jones retired her horse Kirby Park Irish Jester and withdrew from the Australian International Three Day event in Adelaide from Friday.

Jones, who won an Olympic teams eventing silver medal on Jester at the 2008 Beijing Games, planned to compete for the last time on the horse in Adelaide.

But an adductor injury had beaten the 19-year-old Jester, who was the world's top-ranked eventing horse in 2008.

"Because I have trained and ridden Jester from the very start, it makes for a partnership like no other," Jones said.

"I will miss every aspect of competing him at top level as I trust him with everything I have.

"Every horse I ride will be measured against Jester - they all have a lot to live up to."

AAP