Antihistamines and NSAIDs and nutraceuticals, oh my! Have a question about equine drugs or medications at Equestrian Canada (EC) sanctioned competitions? EC’s Equine Medication Control Committee is here to answer your questions on the EC Equine Medication Control program.

Can my horse compete while being given Regumate?

Yes, if your horse is a mare. As outlined in EC General Regulations, Article A1003: Permitted Medications and in the list of permitted medications in the EC Equine Medication Control Guide, in competition Regumate (alternogest) is permitted in mares but prohibited in geldings and stallions.

I recently purchased a new horse from the United States. I was told that the horse had never received any medroxyprogesterone, but am not confident that this is the case. What do I do to make sure that I am compliant with EC rules, which prohibit the use of medroxyprogesterone?

This is a very good question that highlights one of the issues in purchasing horses from the United States, where medroxyprogesterone is not a prohibited substance. Contrary to a common belief, medroxyprogesterone does not prevent mares from coming into season.

Medroxyprogesterone has a long and indeterminate withdrawal time which depends on the product being used, as well as the dosage and frequency of administration. Due to these variables, no actual withdrawal time can be recommended. The best approach to ensure that your horse is compliant with the EC medication rules is to have your veterinarian submit blood and urine to a laboratory and request a target test for medroxyprogesterone. A negative test will give you assurance that your horse is free of that drug.

Do you have a question? Send your inquiries about the EC Equine Medications Control program to

Please note, this does not constitute legal advice. Information included in this article is for informational purposes only. It is not, and should not be taken as, advice regarding a particular situation. You should not rely on, nor take or fail to take any action based upon this information. You are encouraged to seek legal advice regarding your circumstances, and you should not rely upon anything you have read in this article without seeking appropriate legal advice regarding the application of EC Equine Medication Control Rules to your particular circumstances.

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