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Kazensky, C. A., Munson, L., & Seal, U. S. (1998). The effects of melengestrol acetate on the ovaries of captive wild felids. Journal-of-Zoo-and-Wildlife-Medicine, 29(1), 1–5.
Abstract: Melengestrol acetate (MGA) is the most widely used contraceptive in zoo felids, but the mechanism of contraception and the pathologic effects have not been investigated. For this study, the effects of MGA on folliculogenesis were assessed, and the association of MGA with ovarian lesions was evaluated. Comparisons were made among the histopathologic findings in the ovaries from 88 captive wild felids (representing 15 species) divided into three groups: 37 currently contracepted with MGA, eight previously exposed to MGA, and 43 never contracepted. Ninety-one percent of the felids evaluated had tertiary follicles, and no differences were noted between contracepted and uncontracepted cats. Some MGA-contracepted cats also had corpora lutea indicating recent ovulation. These results indicate that folliculogenesis is not suppressed by current doses of MGA and ovulation occurred in some cats. Therefore, the contraceptive actions of MGA do not occur by suppressing folliculogenesis, and MGA-contracepted felids likely have endogenous estrogens that may confound progestin effects on the uterus. Cystic rete ovarii was the most common pathologic finding, but they were not more prevalent in MGA-contracepted cats. These findings indicate that MGA is not associated with ovarian disease, including ovarian cancer, in contrast to the uterine lesions noted in MGA-treated cats.
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Roth, T. L., Armstrong, D. L., Barrie, M. T., & Wildt, D. E. (1997). Seasonal effects on ovarian responsiveness to exogenous gonadotrophins and successful artificial insemination in the snow leopard (Uncia uncia). Reprod Fertil Dev, 9(3), 285–295.
Abstract: Ovaries of the seasonally-breeding snow leopard (Uncia uncia) were examined to determine whether they were responsive to exogenous gonadotrophins throughout the year. The potential of laparoscopic artificial insemination (AI) also was assessed for producing offspring. During the non-breeding, pre-breeding, breeding and post-breeding seasons, females (n = 20) were treated with a standardized, dual- hormone regimen given intramuscularly (600 I.U. of equine chorionic gonadotrophin followed 80-84 h later with 300 I.U. of human chorionic gonadotrophin (hCG)). Laparoscopy was performed 45-50 h after administration of hCG, and all ovarian structures were described. Females with fresh corpora lutea (CL) were inseminated, and anovulatory females were subjected to follicular aspiration to examine oocyte quality. Snow leopards responded to exogenous gonadotrophins throughout the year. Mean number of total ovarian structures (distinct follicles mature in appearance plus CL) did not differ (P > or = 0.05) with season, but the proportion of CL: total ovarian structures was greater (P < 0.01) for the breeding season compared with all other seasons. The proportion of females ovulating was greater (P < 0.05) during the breeding and post-breeding seasons than during the pre-breeding and non- breeding seasons respectively. No Grade-1 quality oocytes were recovered from follicles of anovulatory females. Serum concentrations of oestradiol-17 beta appeared elevated in all females, and neither oestradiol-17 beta concentrations nor progesterone concentrations differed (P > or = 0.05) among seasons. Of 15 females artificially inseminated, the only one that was inseminated in the non-breeding season became pregnant and delivered a single cub. This is the first successful pregnancy resulting from AI in this endangered species.
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Schmidt, A. M., Hess, D. L., Schmidt, M. J., Smith, R. C., & Lewis, C. R. (1988). Serum concentrations of oestradiol and progesterone, and sexual behaviour during the normal oestrous cycle in the leopard (Panthera pardus) (Vol. 82).
Abstract: Three mature nulliparous female leopards were studied for 5 years. During three separate 6-month periods serum oestradiol and progesterone concentrations were measured at weekly intervals. Oestradiol was elevated over 21 pg/ml for 54 weeks during these 3 periods, and 36 oestradiol peaks (65\m=.\8\m=+-\6\m=.\3pg/ml (mean \m=+-\s.e.m.), range 21\p=n-\172pg/ml) were identified. Daily frequency of feline reproductive behaviours averaged over each week increased from 1\m=.\9\m=+-\0\m=.\2(n = 93) during weeks with low serum oestradiol concentrations (<21 pg/ml) to 5\m=.\3\m=+-\0\m=.\6(n = 54) during weeks when serum oestradiol concentrations (>21 pg/ml) were high. Increased serum progesterone concentrations (13\p=n-\98n/gml) were observed on 5 occasions in 2 leopards housed together. These presumptive luteal phases lasted from 1 to 5 weeks. Baseline progesterone values were 1\m=.\6\m=+-\0\m=.\4 ng/m(nl= 131). No progesterone increments were observed in isolated animals, and serum concentrations remained at baseline levels. These limited observations suggest that female leopards do not require intromission to induce ovulation and luteal function. The average interval between oestradiol peaks for cycles with no progesterone increment was 3\m=.\4weeks (range 1\p=n-\6weeks). The interval for the 3 complete cycles associated with elevated progesterone concentrations was 7\m=.\3weeks. Analysis of sexual behaviours over the 5-year study period revealed no evidence of seasonality in these
captive leopards.
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