Chris Waller has spoken out in support of fellow trainer Peter Moody and challenged racing's governing body to unite the sport.

Despite training a winner at Canterbury on Wednesday, Waller's mind was clearly on his embattled counterpart in Melbourne.

Moody, already facing cobalt charges, said he was considering walking away from training after he was involved in a raceday treatment probe at Pakenham races.

He accepted responsibility after one of his staff mistakenly applied a clay poultice.

The incident moved Waller to back Moody.

"I just think what's happened today is quite - I wouldn't say unbelievable (but) shouldn't we be here promoting our sport rather than just bringing it down?" Waller said.

"I challenge Racing Australia to start doing that, bring us all together, get us back on track because we've got an amazing sport."

Waller was fined $30,000 and his horse Junoob disqualified from his win in the Group One Metropolitan last year after it tested positive to a banned drug.

He said trainers at the centre of drug inquiries were made to feel like outcasts.

"You deadset get treated and feel like a criminal," he said.

"There is a small percentage of trainers who have let the team down through different eras but you won't get someone who works harder or works harder to promote the sport than Peter Moody."