The effects of melengestrol acetate on the ovaries of captive wild felids

Carol A. Kazensky, Linda Munson, Ulysses S. Seal

Research output: Contribution to journalArticlepeer-review

32 Scopus citations


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.

Original languageEnglish (US)
Pages (from-to)1-5
Number of pages5
JournalJournal of Zoo and Wildlife Medicine
Issue number1
StatePublished - Mar 1998


  • Contraceptive
  • Felid
  • Folliculogenesis
  • Melengestrol acetate
  • Ovary
  • Pathology

ASJC Scopus subject areas

  • Animal Science and Zoology
  • Environmental Science(all)
  • veterinary(all)


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