Trainers Lee and Shannon Hope both knew more about cobalt than they admitted and intentionally administered the performance-enhancing substance to three horses, a tribunal has found.

The father-and-son trainers face a minimum three-year disqualification after being found guilty of administering cobalt to affect the performance of three of their racehorses.

Shannon Hope is likely to face a harsher penalty than his 64-year-old father with Judge Russell Lewis saying the Racing Appeals and Disciplinary Board's preliminary view is that he is more culpable.

Shannon Hope was responsible for the feeding and supplementation regime that the training partnership argued led to Windy Citi Bear, Best Suggestion and Choose returning elevated cobalt levels last year.

The RAD Board found the supplements and intravenous regime was not a credible explanation and agreed with racing stewards that cobalt exceeding the allowed threshold was administered on or before race day.

It said the Hopes both knew far more about cobalt than they admitted and were not credible witnesses in their evidence on cobalt and its use.

"It beggars belief that he (Shannon) would not have known that cobalt was present in many of the supplements and medications and that he would not have appreciated that cobalt had the potential to become a problem," the board said.

"Lee Hope knew what supplements Shannon was administering but denied any knowledge of cobalt, which to the board seems odd, he being an experienced trainer in his own right for many years before entering into partnership with his son.

"His denial that he had any discussion about cobalt with his son with whom he was working side by side, or with their veterinarian (who attended the stables on a weekly basis) especially after receiving the stewards' notice and hearing radio reports of the cobalt threshold, strains credulity."

The Hopes' legal counsel Robert Stitt QC said the board should use its discretion to impose a fine on Lee Hope rather than disqualify him so he could continue training at his Kilmore stable.

"The proper penalty is a fine. It is not appropriate that he should be disqualified from his 50 years of successful training over this incident," Mr Stitt said.

Mr Stitt said Shannon Hope should also face a fine and otherwise a disqualification that was not crushing and would allow him to return to training.

Mr Stitt argued Shannon Hope had overused legitimate substances, as opposed to intravenously administering cobalt chloride or another cobalt substance.

"You've got an over-egging of the pudding," he said.

But Racing Victoria stewards' legal counsel James Ogilvy said the Hopes were found to have deliberately administered cobalt to the horses to affect their performance in races.

"It was not an over-egging or inadvertent scenario," he said on Thursday.

"This is not the case of an isolated act."

The RAD Board will deliver its decision on penalty early next week.