Megan Jones is about to make or break her beloved horse, which helped her win an Olympic equestrian silver medal.

Jones' cherished Kirby Park Irish Jester could have died after falling ill last year.

But from Friday, Jones and Jester take a calculated gamble and return to competition at the Adelaide International three-day event.

"I'm nervous about him not coping, but not nervous about the competition," Jones told AAP on Thursday.

"I'm just nervous about am I doing the right thing bringing him here?"

Jones and Jester were part of Australia's silver-medal winning team at the 2008 Beijing Olympics.

But last September the horse fell ill en route to the World Equestrian Games in Kentucky, USA.

Jester landed in Los Angeles with fluid on the lungs and spiked temperature - a combination which can kill a horse in 10 hours.

Jones wasn't told of the ailment for 12 hours and was initially refused quarantine access to treat Jester.

"They (quarantine officials) threatened me basically, it was just disgusting," said Jones, who summoned equestrian's world governing body to intervene and save her horse.

Jester spent a week in hospital on a drip, then returned to Australia with foot problems and was lame until June this year.

"He's 18 next month, he's an older horse, so it's big for him to come back - fingers crossed," Jones said.

"I just hope he's going to cope, I won't really know until I put the pressure on him, we don't know if his lungs are going to be OK.

"He's feeling really good so I'm quietly confident but you never know."

The 34-year-old Jones wants to take Jester, who she has had since a foal, to next year's London Olympics.

"I hope Jester can last that long," Jones said.

"This weekend will basically tell us if he can or can't.

"If he doesn't cope, then we won't keep going on."

Steve Larkin
AAP