Almost a year after it began, the More Joyous saga has been brought to a close with Racing NSW deciding against pursuing an appeal over a ruling which sided with trainer Gai Waterhouse.

After the Racing NSW appeal panel dismissed her case over conviction and penalties for not reporting the condition and treatment of the mare in the lead-up to two races in the autumn, Waterhouse went to the Racing Appeals Tribunal.

Judge David Armati took the view Racing NSW stewards had not proved their case to the required legal standard, prompting the authority to consider Supreme Court action.

However, on Thursday, Racing NSW said it would not pursue the matter further and confirmed changes to the wording of the rules to remove any ambiguity.

"In particular, it is now clear that the obligation upon trainers to report exists both in respect of occurrences, conditions and treatments that were present prior to acceptance time and after acceptance time," a Racing NSW statement said.

"There is little point in Racing NSW and Mrs Waterhouse incurring further time and expense in a lengthy appeal of these matters when Racing NSW's concerns about protecting the interests of punters have been addressed by the amendment to AR140(a) and the findings on the legal issues in the More Joyous case."

Problems with More Joyous came to light after she was unplaced in the All Aged Stakes when the horse's owner John Singleton publicly accused Waterhouse's bookmaker son Tom of saying More Joyous could not win.

In a post-race television interview, Singleton sacked Waterhouse as his trainer, prompting a high-profile inquiry.

Waterhouse did not tell stewards More Joyous had a sore neck in the days before the All Aged Stakes on April 27.

During the long-running inquiry, Waterhouse revealed the mare had been mildly lame with a foot abscess a week before her unlucky fifth in the Queen Of The Turf Stakes on April 6 which stewards ruled should have been reported.

The All Aged Stakes turned out to be the last racetrack appearance by More Joyous who was sent to England to be mated with Frankel.

Tom Waterhouse was cleared of any wrongdoing and Singleton was fined $15,000 for his conduct.

Waterhouse moved on from her association with Singleton to claim her first Melbourne Cup in November with Fiorente.