Racing Victoria stewards scratched Axis Point from a race at Warrnambool on Tuesday on the suspicion it had received race-day treatment.
Deputy chief steward Rob Montgomery said stewards had received a report that the Peter Gelagotis-trained Axis Point may have been treated.
"The Compliance Assurance Team this morning inspected Mr Gelagotis' horses on two occasions and reported that the horse may have been treated with an amino acid," Montgomery said.
"They have confiscated a syringe and taken some products and we scratched the horse because it may have been treated."
Axis Point was withdrawn less than an hour before he was due to race and stewards have adjourned an inquiry.