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al-TREN-o-jest - Pronunciation guide

Brand Names

  • Regu-mate Solution


Regu-Mate (altrenogest) Solution 0.22% produces a progestational effect in mares.


Rx symbolAltrenogest is used for suppression of estrus. The mare will experience a predictable occurrence of estrus following drug withdrawal. This allows a regular cycle during the transition from winter anestrus to the physiological breeding season in mares with active ovaries. By managing the reproductive cycle, horse owners have more control over breeding procedures and the timing of the arrival of foals.

In some cases, Regu-Mate Solution is used for pregnancy maintenance. It is also used for reduction of aggressive behavior in stallions.

Dosage and Administration

Prescription medicationAltrenogest
Method Dosage
(click row for calculator)
Concentration Period Duration
Oral 0.044 mg/kg 2.2 mg/ml 15 days NA


  • Federal law restricts this drug to use by or on the order of a licensed veterinarian.
  • Use protective gloves when handling this medication.
  • Administer solution directly on the base of the mare’s tongue or on the mare’s usual grain ration.
  • Calculator is for educational purposes only. Follow your veterinarian's instructions regarding use of this, or any medication.

Side Effects

No recognized side effects are reported in horses when Regu-Mate is used according to label directions.


If Regu-Mate is added to feed, any medicated feed left over should be destroyed and should not be given to other animals.

Regu-Mate should not be handled by women of child-bearing age. Protective clothing and gloves should be worn when handling Regu-Mate.

Regu-Mate should not be administered to immature animals, or animals with diabetes, uterine infection, history of vaginal discharge, or reproductive abnormalities.

Regu-Mate is not for use in horses that are intended for human consumption.

Regu-Mate is FDA-approved for use in horses. It is a prescription drug restricted to use by or on the lawful written or oral order of a licensed veterinarian. It may be permitted in mares at FEI competitions. It is important to check with the proper individual regulatory body.


Rifampin may increase the speed of metabolism of Regu-Mate.


Check manufacturer's directions.


Altrenogest SolutionAltrenogest Solution


Product labels

The drug labels on this website represent drug information listings as submitted to the FDA.The drug labels on this website have not been altered or modified by EquiMed. The drug labels on this website may not be the most current or identical to the current labels shipped with the product. Contact your veterinarian or the manufacturer for the latest information on this drug or medication prior to use.

About the Author

EquiMed Staff

EquiMed staff writers team up to provide articles that require periodic updates based on evolving methods of equine healthcare. Compendia articles, core healthcare topics and more are written and updated as a group effort. Our review process includes an important veterinarian review, helping to assure the content is consistent with the latest understanding from a medical professional.