Caulfield trainer Byron Cozamanis is the new trainer of Cox Plate runner Happy Trails following the failure of Paul Beshara to gain a stay of proceedings to allow him to saddle the horse on Saturday.

The shock decision came at the end of a day in which Beshara was disqualified for six months for administering an unspecified treatment to Happy Trails on the morning he was due to race in the Dato Tan Chin Nam Stakes at the Valley last month.

Beshara applied to the Victorian Civil and Administrative Tribunal (VCAT) for the stay that would have allowed the horse to run in his name in Saturday's feature.

VCAT refused the application but will attempt to hear an appeal by Beshara against the guilty verdict before the end of the week.

Earlier, Victoria's Racing Appeals and Disciplinary (RAD) Board used a new rule that calls for a mandatory six month ban for the offence which it had found Beshara guilty of last week.

"I'm going to appeal, I think we have strong grounds," Beshara said.

"I still say I did nothing wrong. This is the biggest kick in the guts I've ever had.

"In 40 years of training I've never even had a fine before."

It is expected Beshara will be granted a stay of proceedings pending the appeal to allow Happy Trails to run in his name on Saturday.

In the hearing that concluded last week, the RAD Board ruled in favour of the stewards who inspected Happy Trails on the day he was to have raced and found a puncture mark on his neck they said was evidence the horse had been injected.

They found no syringe or other equipment with which the horse could have been treated, and no traces of prohibited substances were found in blood samples.

But the Board described Beshara's alternative explanations for the puncture mark and an accompanying haematoma as "fanciful".

The previous Victorian trainer to be found guilty of the same offence was fined $8000 in circumstances that appeared less convincing than those surrounding Beshara, prompting RAD Board chairman Judge Russell Lewis to sympathise with Beshara's plight.

"I understand it would be a cause of some grievance," Lewis said.

The RAD Board earlier explained to Beshara and his counsel the only grounds on which they could argue for anything less than the prescribed six month sentence were if such a penalty might be contrary to "the interests of justice".

But no such grounds could be made out by Beshara or his advocate.

Beshara, 64, said if his appeal failed the penalty meant the end of his career.

"Who's going to give a bloke of my age another go," he said outside the inquiry.

The penalty means Beshara is prohibited from entering licensed premises, including racing stables, meaning he must move from the Adelaide property where he lives and stables his horses, or remove the horses.