James McDonald has lost his second tier appeal against the severity of an 18-month disqualification for betting on a horse he was riding.

Judge David Armati of the Racing Appeals Tribunal on Monday dismissed McDonald's appeal against the severity of the ban for placing a bet on Astern when he won his debut in December 2015.

The Racing NSW Appeal Panel also dismissed McDonald's appeal but the three-man tribunal was split 2-1 with principal member Richard Beasley saying there should be a lesser penalty for a jockey betting on a horse he or she was riding as opposed to a rival horse.

But Armati disagreed.

"The Tribunal does not accept the appellant's argument that placing a bet by a jockey on a jockey's own mount creates reduced conflicts because the incentives of the jockey in riding and winning a bet are aligned," his judgment said.

"This is particularly so because, unlikely as it is, if the public found out a jockey was not betting money on a jockey's own horse there would be an impact on betting markets and integrity questions raised. It is however a less serious activity than betting on another jockey's mount."

Armati also said the 25 per cent discount on the mandatory two-year penalty afforded McDonald was adequate and made mention of the amount of time it took the jockey to come clean to stewards about the $1000 bet placed on his behalf by professional punter Anthony Gardiner.

Stewards had been aware of McDonald's association with Gardiner who has been warned off after failing to appear for questioning.

McDonald, who lost his retainer with global racing power Godolphin, can return to riding in May 2018.