Trainer Gordon Yorke has been disqualified for 18 months after one of the stable's horses returned a cobalt reading more than 40 times above the threshold.
A pre-race sample taken from the Yorke-trained Follow Through at Grafton in July last year showed a level of 4413 mcg/L with the threshold set at 100.
Yorke pleaded not guilty to presenting the mare to race with an elevated cobalt level but Racing NSW stewards found against him.
His ban was backdated to start on December 21, 2017, the day he was stood down from training for failing to attend a hearing.