Gai Waterhouse has called for an overhaul to the rule requiring trainers to report health issues in horses after being found guilty of not revealing More Joyous was lame leading into the Queen of the Turf Stakes.

Waterhouse already has a case under appeal for not reporting treatment given to the glamour mare before she finished second last in the All Aged Stakes on April 27.

In a post-race interview, the mare's owner John Singleton launched his infamous public tirade against Waterhouse and sacked her as his trainer, prompting an inquiry after which he was fined $15,000 for misconduct and the trainer fined $5000.

Waterhouse appeared before Racing NSW stewards on Tuesday over the condition of More Joyous who was found to be lame a week before the Queen of the Turf but in Waterhouse's expert opinion, was fit later in the week.

"I'm disappointed with the stewards' decision," Waterhouse said after being fined $2000.

"I take great care of all my horses and I wouldn't have raced a horse if it wasn't fit or healthy.

"The trainers believe the interpretation of this rule is untenable, and the meaning of the rule is already the subject of an appeal that will affect all trainers."

More Joyous finished fifth in the Queen of the Turf after being held up for a run with stewards acknowledging on the day she was unlucky not to win.

Waterhouse's vet Leanne Begg found the mare to have grade 2 out of 5 lameness after she worked on Saturday, March 30.

A deep-seated hoof abscess was found the following day and the hoof continued to be bathed and poulticed.

By acceptance time on Wednesday, the lameness was assessed at 1/5 and Waterhouse declared More Joyous a runner in the Group One race.

More Joyous did not gallop on the track before the race with Waterhouse instead sending her to Botany Bay to work in the water which she said was just as physically demanding.

"She could not have been fitter," Waterhouse said.

"I chose to swim her in the most boisterous conditions. Three minutes swimming in Botany Bay is arduous exercise.

"It's not just swimming in a pool. It is high cardio vascular work ploughing through the water.

"She never missed any exercise."

Waterhouse said as the trainer it was her opinion on the Wednesday that the mare had almost completely recovered and would be at her peak by race day.

Chief steward Ray Murrihy said his panel believed the two cases involving More Joyous were different.

"We do not consider the matter comparable to the issue before the All Aged Stakes when More Joyous was receiving veterinary attention up until the morning of the race," he said.

Waterhouse said she would consider appealing Tuesday's conviction.