Judge Russell Lewis, outgoing chairman of the Racing and Appeals Disciplinary Board, has handed down potentially career-ending guilty verdicts to trainers Danny O'Brien, Mark Kavanagh and Melbourne-based veterinary surgeon Tom Brennan.

All three were found guilty of administering cobalt for the purposes of affecting performance of a horse in a race.

It's considered a serious 'doping infraction' in racing and carries a mandatory three-year disqualification.

O'Brien had four cobalt charges against him with fellow Flemington trainer Kavanagh facing one and their former vet Brennan associated with all five positives.

It appears certain that all three will appeal the decision and will seek a stay and take the appeal to Victorian Civil and Administrative Tribunal.

The board will reconvene on a date to be fixed to hear penalty submissions for Kavanagh, O'Brien and Brennan.

Early in February, trainers Lee and Shannon Hope will appeal their three- and five-year disqualifications respectively at VCAT.

The case of Peter Moody, charged with having imported stayer Lidari return an elevated cobalt reading at Flemington last year, will continue in February.