Just how long Whistle Baby races on depends on her performance at Moonee Valley.

The six-year-old runs in Saturday's G J K Facility Services Handicap (1200m) which may turn out to be her last start.

But if she happens to win, the career of the Mathew Ellerton and Simon Zahra-trained mare may be extended.

Zahra said the Listed All Victorian Sprint Final (1200m) at Flemington on July 8 could be her swan song.

Whistle Baby will be going to stud for the second time.

She was retired 12 months ago but failed to get in foal to Vancouver and came back to racing.

This spring she will be served by Written Tycoon.

Zahra says there's time for one more race after Saturday, but the stable prefers to allow their mares the opportunity to let down before they go to stud.

"She's getting on a bit now and it's getting time for her to being a mum so we'll give her every opportunity again to get in foal," Zahra said.

Zahra says Whistle Baby has been a great mare for the stable and it would be ideal for her to get a stakes race victory under her belt.

But he is concerned the Flemington race may be too tough, especially if the track is firm.

"She's been stakes-placed twice and it would be good to get that stakes win on the board," he said.

"But I'd say that race may be a bit rich. I'd say Saturday would be her last go especially as the tracks get a bit firmer."

Ellerton and Zahra will also be represented by Josephine Sea in the Friends Of Epworth Handicap (1200m) and Essence Of Terror in the Zouki Handicap.