Racing Victoria stewards are investigating a positive swab returned by a Tony Vasil-trained horse subsequent to a Moe barrier trial.

Stewards on February 27 informed Vasil of Racing Analytical Services Limited (RASL) confirmation of a prohibited substance found in a urine sample taken from Cloanthy after the mare ran second in the 1000m trial on January 23.

Traces of Hydroxyethylpromazine, which is a major metabolite of acepromazine that is used as a tranquillising agent, were detected.

Cloanthy had to trial satisfactorily to be reinstated for racing after stewards suspended her from racing for unruly behaviour when she was a late scratching at Ballarat on January 12.