Besides earmarking these successful stables, stewards have also conducted random out of competition samplings for the performance enhancing drug and other prohibited theraputic substances in the lead-up to racedays.

David Hayes' Lindsay Park establishment was the last of the trio of trainers, including Mark Kavanagh and Richard Jolly to have entertained the stewards for the purpose of EPO testing with samples taken from 20 horses.

Between the Morphettville-based Jolly and Kavanagh a further 18 gallopers had the rule run over them by TRSA.

"The selection of the Hayes, Kavanagh and Jolly stables were simply upon the basis that they were the leaders in this state," chairman of stewards, Graham Loch, said.

"Hayes is usually at the top of the table, Kavanagh won this year's Melbourne Cup and Richard Jolly's horses are racing well."

Loch prepared a report for the TRSA Board, requesting funding to carry out the EPO (Erythropoietin) testing and after five months 130 horses have been sampled - so far without out one positive return - and he expects around 300 runners to have come under the microscope by season's end.

"We (Loch and his panel) will continue to pay attention to a spike in form; if a horse's level is elevated or where they are ultra-consistent," he said.

"In the main testing has been relevant to racedays; if a horse is nominated for Saturday, samples would be taken following a the horse's final gallop, either on a Wednesday or Thursday because if EPO is provided it is only in the system for a short period of time which gives us a window of about 36 hours."

He added that random sampling had so far been conducted in the Fleurieu Peninsula region, at Strathalbyn and twice at Murray Bridge, where one stable had come under the stewards' scrutiny, and Morphettville with eventually all SA's racing jurisdictions being covered.

EPO is a naturally occuring hormone that regulates the production of red blood cells which carries oxygen through the body; the artificial Erythropoietin-stimulating agent was initially produced to help people with chronic anaemia or cancer.

Referred to as "blood doping", EPO is believed to accelerate the horse's ability to produce red blood cells, increasing the metabolism and healing process of muscles allowing for added stamina and speed, two elements which are important for a competitive racetrack environment.

Although Loch said there was still no science which supported EPO's benefit to horses, he believed the cornerstone of the racing industry hinged on its integrity which meant providing a level playing field for all investors in the industry.