Stewards ordered the late scratching of a Ricky Maund-trained horse from a race at Caulfield on Saturday on suspicion it had been treated on raceday.

The Maund-trained Uncle Keithy was scratched from the VOBIS Gold Reef less than 20 minutes before the start after stewards opened an inquiry following a report from the compliance assurance team.

Chief steward Terry Bailey said he was concerned the horse had received raceday treatment against the rules of racing.

"On the evidence before us, we were concerned that this particular horse had received treatment consistent with a slurry of bi-carb," Bailey said.

Bailey said evidence was taken from Maund and two staff members.

Plungers for a syringe and some residue were confiscated for further analysis.

The chief steward said Maund denied Uncle Keithy had been treated.

"He was of the view that it was for another horse that wasn't racing on the day," Bailey said.

The inquiry has been adjourned.