Altrenogest is indicated (labeled) to suppress estrus in mares to allow a more predictable occurrence of estrus following withdrawal of the drug. It is used clinically to assist mares to establish normal cycles during the transitional period from anestrus to the normal breeding season often in conjunction with an artificial photoperiod. It is more effective in assisting in pregnancy attainment later in the transition period. One group of authors (Squires et al. 1983) suggest selecting mares with considerable follicular activity (mares with one or more follicles 20 mm or greater in size) for treatment during the transitional phase. Mares that have been in estrus for 10 days or more and have active ovaries are also considered to be excellent candidates for progestin treatment.

1.Altrenogest can widely used in veterinary medicine to suppress or synchronize estrus in horses and pigs.
2.Altrenogest is used in mares to facilitate scheduled breeding activity.
3.Altrenogest is also used to suppress estrous behavior in performance horses.
4.Altrenogest is indicated to suppress estrus in animals to facilitate induction of normal estrous cycle activity.