Well-performed northern hemisphere galloper Wichita's future is in doubt after he sustained a serious leg injury at the Werribee International Horse Centre.

The Aidan O'Brien-trained four-year-old suffered a fracture to his right hind leg on Wednesday, which was detected after he had completed his trackwork and returned to his box.

Racing Victoria and stable veterinarians are currently assessing the horse's injury to determine an appropriate management plan.

Wichita's primary target during the spring racing carnival was the Group One Cantala Stakes (1600m) on October 31 for which nominations are yet to close.

The horse will not be entered for any races and will remain confined to his box under veterinary care.

In nine starts, Witchita had demonstrated his class with a win in the Group Two Park Stakes at Doncaster over 1400 metres and three Group One placings, including a second in the Thousand Guineas at Newmarket.