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Notice: Using oral Altrenogest in racehorses

Thursday, 8 November 2018  
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Original notice: 28 October 2018

Veterinarians are advised that from 1 November 2018 the withholding time for the use of oral Altrenogest in racehorses will change from ‘one clear day’ to ‘ two clear days’. See this letter for further information. The information in this letter also applies to FEI competition horses.

 This notice replaces the notice on 20 September 2018 and is in response to the development of more refined methods for detecting sex hormones and anabolic steriods including  Trenbolone and Trendione.

 Altrenogest is exempt under the Prohibited Substance Regulations when used in females. Two listed impurities found in Altrenogest, Trenbolone and Trendione are anabolic steroids and prohibited substances under both HRNZ and NZTR Prohibited Substance Regulations. The ban on  the use of all injectable forms of Altrenogest in racehorses remains in place because Trenbolone  and Trendione will be detectable in post race urine samples.

Pharmacokinetic studies in mares are on going and these current recommendations may not be  the final notice on the subject.

Veterinarians are strongly advised to:

  1. Cease using Altrenogest Injections in racing females.
  2. When using oral Altrenogest in racing females use the listed label dose rate. Do
    not double dose.
  3. Stop using oral Altrenogest in racing females ‘two clear days’ from racing.
  4. Do not use female hormones including Altrenogest on any male horses at any
    time. It will be detected in any ‘out of competition’ testing.

Update: 8 November 2018

Altrenogest use in sport horses
Provided by Tony Parsons BVSc, NZ FEI National Head Veterinarian

Under FEI and ESNZ rules it is allowable to use Altrenogest to suppress oestrus in mares during competition. Its use in geldings or stallions is not allowed.

Since January 2018 it has not been a requirement to declared usage.

Due to recent concerns over traces of anabolic steroids being detected after the use of injectable Altrenogest, it is recommended that only oral Altrenogest be used at the manufactures dose rate.

FEI advice is based on the brand Regu-Mate (2.2 mg/ml Altrenogest). There are several other similar products available on the market in New Zealand. The prescribing Veterinarian takes responsibility for these products performing in the same way as Regu-Mate.