William Haggas hopes Addeybb is "over the worst" after an infection left him fearing the star globetrotter might never race again.
An infected blood clot caused the group 1 winner to lose a significant amount of weight and left Haggas concerned for his welfare.
The son of Pivotal finished sixth in the QIPCO Champion Stakes (G1) at Ascot last month, a race he won in 2020, but was subsequently lame and then spent time with the vet after the clot was discovered.
Haggas said: "Unfortunately Addeybb developed a blood clot on his hock after the Champion Stakes, which got infected. He came home from the vets a few days ago and the bloods we've taken from him since indicate he's going the right way.
"When I first went to see him I thought he looked dreadful. To my eye he looked like he had lost 50 kilos in a week. When I spoke to his owner I said there is a strong chance that he may not race again.
"I'm not saying he was never going to live but these things can go badly wrong. He looks a lot brighter now. I think and hope we are over the worst."
A third consecutive appearance at the Sydney Autumn Racing Carnival in 2022 has already been ruled out.
On his last Australian trip, the 7-year-old beat subsequent Lexus Melbourne Cup (G1) winner Verry Elleegant when landing the Longines Queen Elizabeth Stakes (G1) for a second time at Randwick in April.
Addeybb, who was taking his Aussie group 1 tally to three that day, has had only two domestic races this year.
Haggas said: "Hopefully in the next fortnight we can turn him away in a paddock for a break, but we'll have to give Australia a miss this time."