An anonymous tip regarding the bona fides of the training of Al Dhafra prompted the scratching of the galloper from a race at Warwick Farm on Saturday.

The six-year-old is registered as being trained by Wayne Hudd at Goulburn but stewards were alerted he was in fact being prepared on the property of prominent harness racing identity Dennis Day.

Mark Day and Todd Day, the brother and son respectively of Dennis Day, brought the horse to Warwick Farm in a float with a standardbred horse as a companion.

Mark Day, who is part-owner of Al Dhafra, did not drive the float on course but instead dropped Al Dhafra off at a stable in Bull St where Troy Tripping, a foreman for local trainer Bjorn Baker, took the trotter to a sand roll at Baker's stable.

Samples were taken from Al Dhafra who was due to return to the races after a 12-month injury lay-off.

Stewards questioned Mark Day who admitted Al Dhafra had spent the past month at the property of his brother Dennis where he did slow work.

"He gets led off the back of a sulky," Day said.

Day said he was not familiar with Warwick Farm which was why he had not driven on to the course.

"We received an anonymous tip and are satisfied there is evidence that the horse isn't being trained in accordance with the rules," Racing NSW chief steward Ray Murrihy said.

Jim Walshe, chief steward in the south eastern district, was despatched to the properties of Hudd and Day in Goulburn on a fact-finding mission.

The incident comes just a week after Rosehill trainer Greg McFarlane admitted he was about to administer a stomach tube to a horse that was due to race that afternoon after being observed by racecourse detectives.

Stomach tubes are generally used to administer bicarbonate which is believed to slow the build-up of lactic acid in performance animals.

Investigations into the Al Dhafra case are continuing.