The racing career of promising filly Koshu (NZ) (Satono Aladdin) is over.

The New Zealand-bred filly carried the colours of her breeder-owners Trelawney Stud to victory in her sole raceday start over 1100m on the Kensington track at Randwick.

She was making pleasing progress in her spring preparation, but injury has curtailed her racing career and she will head home to Cambridge to begin her new career as a broodmare.

“Unfortunately she has gone amiss,” trainer John O’Shea told RacingHQ.

“She developed a spiral fracture in her off-hind (leg) and she will be retired.’

“It is really disappointing.”

Koshu is a daughter of Group One winner Satono Aladdin and out of Traditionally mare Syrah, making her a half-sister to Group One winners A Touch Of Ruby and Loire.