Racing NSW has introduced a threshold level for trace levels of the anabolic steroids trendione and/or trenbolone found in products used to regulate the cycles of fillies and mares.

In June trace levels of the anabolic steroids were detected in certain batches of veterinary prescription animal remedies containing the progestagen altrenogest which is used to control cyclic activity.

After considering scientific and veterinary opinions, the board of Racing NSW has approved the introduction of NSW Local Rule of Racing 44A, which provides Racing NSW with a discretion to find the provisions of AR175(h)(ii), AR177, AR177A, AR177B, AR178 and AR178H do not apply should non-consequential - below 1 microgram per litre - trace levels of trendione and/or trenbolone, together with altrenogest, be detected in a sample at any time.

"The use of altrenogest products in fillies and mares has been permitted in racing for many years," Racing NSW chief executive Peter V'Landys said.

"Its use helps alleviate work, health and safety issues as well as ensuring that all horses race consistently.

"Given the insignificant trace levels found in these oral substances and having regard to advanced testing equipment used by the Australian Racing Forensic Laboratory and the fact that it's so minuscule it has no effect on the horses performance, the Board has introduced the local rule 44A to safeguard the NSW racing industry by allowing fillies and mares to continue to be administered oral altrenogest."

Trainers have been advised not to use injectable products containing altrenogest and not to use oral altrenogest products within one clear day of racing until further notice.