Vaccines against gonadotropin-releasing hormone (GnRH) and porcine zona pellucida (PZP) are known as GonaCon™ and ZonaStat-H/ZonaStat-D, respectively. Both have been approved by the U.S. Environmental Protection Agency for contraception in female wild horses, wild burros, and white-tailed deer, and provide suppression of fertility a year or more, with boosters required for prolonged suppression.[21][22][23] GonaCon has been studied in male and female dogs and cats but does not provide long-acting suppression of fertility in these species.