Trainer Sir Henry Cecil says Frankel has provided him with "strength" during a season in which he is undergoing treatment for stomach cancer.
The world's best racehorse left his Warren Place stable in Newmarket on Thursday to next year begin a new career as a stallion at his birthplace, Banstead Manor Stud.
Frankel left the racing scene with an unbeaten record of 14, his final appearance coming in the Qipco Champion Stakes at Ascot last month.
"He has given me so much strength this season when I have had health problems," said Cecil.
"My feeling was that I had to be there for him at home and on the racecourse, only missing the Sussex Stakes because of treatment.
"There are a lot of people in the yard who have played their part with Frankel and I really appreciate everyone's efforts.
"I want to thank my wife (Jane) for helping me through, what I have to admit, has been a difficult year in more ways than one.
"Without her by my side, I am certain that I would not have been able to do it.
"Jane and I are very fortunate that Banstead Manor is only 10 minutes away from us so we can continue our friendship with Frankel," the Newmarket handler told his official website.