Regumate Side Effects

Regu-Mate is the brand name for altrenogest, which is progestin, a synthetic version of the hormone progesterone. This is given to a filly or mare to keep her from coming into heat at crucial times. A filly or mare in heat will be too distracted to perform well in competitions.

  1. Common Side Effects

    • The most common negative side effect in fillies and mares is that their genitalia increases in size. Another was that the horse goes into heat anyway, which, according to Regu-Mate's manufacturer, happens to 5 percent of fillies and mares.

    Precaution

    • Be absolutely sure that the mare is not pregnant before starting Regu-Mate because it could cause birth defects in the foal.

    Considerations

    • According to Intervet, Regu-Mate should not be given to mares with a previous history of uterine inflammation because it could cause the mare's uterus to become inflamed again.

    Side Effects--Stallions

    • An off-label use of Regu-Mate is to calm stallions down. According to Dr. Bob Judd, DVM, it can also cause fertility problems and should not be used.

    Warning

    • Regu-Mate can interrupt the menstrual cycle of women and may cause abortions in pregnant women. Women should always wear gloves when handling Regu-Mate.