Posted: Oct. 9, 2018
Recently, there have been several positive findings for low level detections of the anabolic steroids trenbolone and trendione in Australia.
Trenbolone is considered an androgenic anabolic steroid (AAS) with several formulations having FDA approval for use in cattle. Trendione is a metabolite of trenbolone and an AAS. There are currently no FDA approved medications containing trendione.
The Australian findings were reportedly linked to the administration of a recently introduced injectable altrenogest product.
Altrenogest is a progesterone receptor agonist used to control estrus in fillies or maintenance of pregnancy in mares. It is marketed in the United States as an oral formulation known as Regu-Mate. Recently, the FDA released a communication to inform those handling altrenogest of potential human health concerns posed by exposure to the drug. That document can be found here.
In 2014 the California Horse Racing Board issued an advisory after detecting trenbolone in a specific lot of Regu-Mate. That advisory can be found on the second page of this document. Since 2014, there have been no findings for trenbolone in California. This is true even though fillies and mares in California have continued to use altrenogest as reflected in post-race testing results.
In 2015 the Canadian Pari-Mutuel Agency had a finding for trenbolone in a post-race urine sample. Subsequently, the CPMA’s laboratory performed an administration study of altrenogest on several horses. In that case, some of the horses administered altrenogest had findings of α-trenbolone in their urine at 24 hours post-administration. The laboratory did not detect trenbolone in any blood samples post-administration.
The regulation of altrenogest is specific to each state. The RMTC recommends that altrenogest remain a non-violation in fillies and mares unless administered in contravention of the jurisdiction’s mandatory stand down or other restrictions. Altrenogest should be considered a Class 4/C substance in geldings, colts and horses. The ARCI currently lists altrenogest as a Class 4/C substance without exception based upon sex.
Trainers should be aware that the use of altrenogest may pose a risk of a positive finding for trenbolone or trendione. Trainers are recommended to use caution when using altrenogest and consider saving samples from any altrenogest containers until all post-race tests from sampled horses have been completed.