Ipswich winner Bosendi has been disqualified after a rare case involving the substance altrenogest being found in a urine sample taken from a gelding.
A Queensland Racing Integrity Commission spokesperson said it was the first case involving a gelding and altrenogest since the Commission began operating four years ago.
Altrenogest has been the centre of debate in the past year over its use in controlling reproductive cycles in mares
QRIC last week announced it would follow the national rule and prosecute cases where levels of the drug were above the proscribed level.
NSW has a rule which allows stewards discretion in dealing with the cases.
Queensland stewards opened an inquiry after Bosendi returned a positive test to altrenogest after winning at Ipswich on May 24.
Evidence was tabled from the Racing Science Centre, the Australian Racing Forensic Laboratory and Murwillumbah trainer Angela Graham.
Graham was charged with bringing a horse to race with a prohibited substance.
She pleaded not guilty.
Stewards found Graham guilty and fined her $3000.