GnRH agonist Lupron (leuprolide acetate) pre-treatments prevent ovulation in response to gonadotropin stimulation in the clouded leopard (Neofelis nebulosa)

In many species, controlling the ovary prior to induction of ovulation improves the success of ovarian response and artificial insemination (AI). We assessed the impact of suppression of estrus with the GnRH agonist, Lupron®, on ovarian sensitivity to equine chorionic gonadotropin (eCG) and human chorionic gonadotropin (hCG) in the clouded leopard. Seven female clouded leopards were given two injections of Lupron® (3.75 mg IM) 23 d apart, followed 44 d later by eCG and hCG. Daily fecal samples were collected from 60 d before Lupron® to 60 d after hCG. Fecal metabolites of estrogen (E) and progesterone (P) were measured by radioimmunoassay. Lupron® decreased (P < 0.05) the number of E peaks during Lupron® treatment compared to pre-Lupron®. All females had baseline E and six of seven (86%) had nadir P on day of eCG. Exogenous gonadotropins induced E elevations in all females. However, mean E in the gonadotropin-provoked estrus was decreased (P < 0.05) compared to pre-Lupron® estrous periods. Only one of seven (14%) females ovulated after eCG/hCG. In conclusion, estrous cycle control with Lupron® resulted in predictable ovarian suppression prior to gonadotropin stimulation but altered ovarian sensitivity by an as yet unknown mechanism so that ovulation was inhibited, even when using a proven exogenous gonadotropin protocol.