Racing Victoria stewards have announced an investigation into a minor irregularity in a blood sample taken from a horse trained by premier trainer Darren Weir before a jumpout in June.
Racing Analytical Services Limited analysts determined the Weir-trained Air Guitar tested positive to Phenylbutazone and Oxyphenbutazone (non steroidal anti-inflammatory substances) before a jumpout at Burrumbeet on June 22.
Stewards informed Weir of the initial test results before confirming the findings on Monday.
Stewards will continue their investigation into that matter and an occurrence of a horse from the Simon Morrish stable testing positive to the same substances on the same day.
The presence of the substances was also reported in a blood sample from the Morrish-trained Miss Astronomoore.
Stewards charged Morrish with alleged raceday treatment earlier this month when they completed their investigation of the withdrawal of the Morrish-trained Show A Star from a race at Flemington in July.
The trainers are likely to receive fines if found guilty of the Burrumbeet offences.