Top Hong Kong galloper California Memory is out of next month's International meeting and his racing career is in jeopardy.

Scans have shown California Memory, a two-time winner of the Hong Kong Cup as well as two other Group One races, has injured his right foreleg.

A popular grey galloper, California Memory returned to racing at Sha Tin on Sunday with an eye-catching fourth.

But there was soreness evident in the horse's right front fetlock, prompting trainer Tony Cruz to order a thorough examination.

"It's a very significant injury to his suspensory and his future is certainly in doubt," Cruz told the South China Morning Post.

"He's a horse who has always had problems with his joints, right from the time he came into the yard, and the Jockey Club vets did a great job to keep him coming up but this could be the end."

Cruz said California Memory would find it difficult to make a comeback because he is a rising eight-year-old.

"If he is going to take a long time to get back to the shape where we could look at racing him again, then it might be a better idea to retire him," he said.