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The Terry Kennedy-trained mare pulled up sore after her last start in January's Gore Cup.
Kennedy and Princess Brook's owner-breeder, Fred King, immediately decided to retire her.
Princess Brook cemented her future as a broodmare prospect with multiple black-type placings in her 44-start career.
She ran third in the group 3 White Robe Lodge Weight-For-Age and in the listed Dunedin Gold Cup.
Princess Brook notched another important black-type placing when third in the listed Spring Classic at Riccarton.
The best of Princess Brook's nine career wins came in the Gore and Tapanui Cups.
King said he was considering future options for the Raise The Flag five-year-old from Lesley Brook.
He said he had many months before the next season.
"We are thinking of selling, but it depends on her value - there is no hurry at the moment."
Should Princess Brook leave King's broodmare band, he will not be left without a nice mare to breed from.
"I have still got Lesley Brook, Miss Millbrook, Sally Brook and Kay's Command to go on with."
King said he was in the process of selling the Mosgiel property where he keeps his breeding stock.
"I have still got a few racehorses to race through yet."
Princess Brook's full brother, Prince Of Brooks, recently returned from Australia after campaigning for clients of recently disqualified trainer Darren Weir.
King said he plans put the horse back in work in the autumn.
"He won a race and had a reasonable amount of placings over there.
"He is at home now, he won't go back in to work until April or May so he can have a good spell."