News of Danny O'Brien's cobalt positives was leaked to fellow Victorian trainer Peter Moody, an inquiry has heard.
Moody told O'Brien in January 2015 he had heard the Flemington trainer may also have a cobalt positive.
Racing Victoria chairman David Moodie spoke to Moody immediately before the trainer called O'Brien, the Victorian Civil and Administrative Tribunal has heard.
Moody was informed of his cobalt case a day before O'Brien and Mark Kavanagh, who are appealing their cobalt disqualifications.
O'Brien and Kavanagh's barrister Damian Sheales asked former Victorian steward Kane Ashby if he aware that information about O'Brien's cobalt positives was leaked to Moody.
Ashby, who is now an internal adjudicator at the new Queensland Racing Integrity Commission, said he was not aware of any leak.
Sheales asked if Ashby would expect the chairman to be informed about cobalt positives before the trainers were told.
Ashby said: "My personal view is no."
Sheales said he would ask chief steward Terry Bailey, at a later date, if he investigated the breach of confidentiality or did not investigate because of who the person was believed to be.
Kavanagh's son, banned Sydney trainer Sam Kavanagh, has also been asked about the evidence Moody knew about O'Brien may have a cobalt positive coming.
Sam Kavanagh referred to Moodie's call beforehand and said: "It's pretty obvious where he got the suggestion from."
VCAT on Wednesday heard Ashby referred to the cobalt positives as "the story of 2015" in an internal email about Moody and O'Brien's preliminary test results.
Sam Kavanagh said his cobalt case had destroyed his career and ruined his family and friends.
"Right now I've got a life sentence and I don't believe I deserve one and it's destroyed me and my family," he said.
Kavanagh was outed by NSW stewards for nine years and three months for offences relating to cobalt and race day treatments, but that was reduced by three years on appeal.
He told VCAT he would never harm his horses and made a stupid error in giving the horse at the centre of his case, Midsummer Sun, a race day treatment before he won the Gosford Cup in January 2015.
"Even though I've been put down as the greatest cheat that's ever been put into racing, I've never knowingly given a horse something that I thought would harm them in any way," Kavanagh said.
Both Kavanaghs and O'Brien had used a substance called vitamin complex, obtained from Flemington Equine Clinic vet Dr Tom Brennan, in drips given to horses that returned cobalt positives.
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