Racing Victoria will not immediately follow the lead of its NSW counterpart in implementing a local rule into the use of altrenogest products.

Racing NSW on Monday introduced a local rule to ensure fillies and mares do not return a positive sample in allowing discretion below one microgram per litre of blood or urine if trace levels of trendione and/or trenbolone, together with altrenogest, are detected.

Trace levels of the anabolic steroids trendione and/or trenbolone have been detected in certain veterinary prescription animal remedies containing progestagen altrenogest used to regulate the cycles of fillies and mares.

Jamie Stier, RV's executive general manager of Integrity Services, said he did not necessarily agree with the Racing NSW move.

He said Racing Australia was the custodian of Australia's rules of racing which not only apply in Australia but also the majority of racing jurisdictions around the world.

"My own view is people need to exercise caution when implementing local rules that are potentially in conflict with national rules," Stier told RSN927.

Stier said RV's integrity team had canvassed a number of suppliers of products that contain altrenogest to try to work out the source of trenbolone and/or trendione to see if it's a batch-to-batch variation or whether it was occurring consistently.

He said RV had not reached a conclusion as work continues.

"Altrenogest has been in use for a long time and there is no issue with the use of altrenogest provided it does not provide findings of trendione and trenbolone," Stier said.

"We're liaising with a number of trainers, not all trainers, we've taken what we believe a fair representative cross section and also spoken with a number veterinarians who have their own views on the way forward."

Stier said RV was working on a resolution to ensure fillies and mares racing in Victoria during the spring, including champion Winx, can do so without the risk of returning a positive.

But he also said rules were in place that had to apply equally for all.

"This is not only specifically to Winx, it's much broader than that," Stier said.

"It's equally important to fillies and mares, not only for their current race, but also their stud careers."