All samples taken from Toowoomba trainer Ben Currie's stable on Weetwood Handicap day have proved clear of any prohibited substances.
However, the Queensland Racing Integrity Commission has again emphasised any treatment of horses on race days without stewards' consent could be found to breach rules of racing.
Numerous swabs were taken from Currie's stable after integrity officers raided it on April 7, the biggest day of racing at Toowoomba.
Currie's father Mark Currie, who is currently training on a stay, was one of three people suspended or disqualified as a result of inquiries after the raid.
Ben Currie is facing 28 charges which will be heard at an inquiry on August 13.
In a media statement released on Thursday, QRIC commissoner Ross Barnett said it was important to be transparent about the test results.
"All testing is now complete and none of the samples taken for testing contained any prohibited substances," Barnett said.
"Officers of the commission took a number of blood and urine samples from seven horses and seized a number of items for testing from the Currie Racing stables on April 7.
"In the aftermath, several Currie Racing employees have been charged and penalised for race day treatment breaches."
Barnett said it was important to realise any race treatment without permission could be found to be illegal.
"I want to make it clear that treating a horse on race day with any medication, prohibited or not, without the permission of the stewards is a breach of the Australian Rules of Racing," he said.
The legal representatives of both Ben and Mark Currie have been informed of the latest findings.
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