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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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Lutz, H., Hofmann-Lehmann, R., Fehr, D., Leutenegger, C., Hartmann, M., Ossent, P., et al. (1996). Liberation of the wilderness of wild felids bred under human custody: Danger of release of viral infections. Schweizer Archiv fuer Tierheilkunde, 138(12), 579–585.
Abstract: There are several felidae amongst the numerous endangered species. Means of aiding survival are the reintroduction to the wild of animals bred under the auspices of man and their relocation from densely populated to thinly populated areas. It is unlikely that the dangers of such reintroduction or relocation projects have been examined sufficiently in respect to the risks of virus infections confronting individuals kept in zoos or similar situations. This report presents infections may be expected to occur when relo- three examples to illustrate that accidental virus cating and reintroducing wild cats. The first example is the reintroduction of captive snow leopards. Zoo bred snow leopards may be infected with FIV, a virus infection that is highly unlikely to occur in the original hirnalayan highlands of Tibet and China. A second example is of several cases of FIP that occured in European wild cats bred in groups in captivity. The third example mentioned is the relocation of hons from East Africa where all the commonly known feline viruses are wide-spread to the Etosha National Park. In the latter, virus infections such as FIV, FCV and FPV do not occur. The indiscriminate relocation and reintroduction of the wild cats mentioned here harbours a potential of undesirable consequences.
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