Understanding basic reproductive physiology is crucial for the management of both captive and free-ranging wolf. In the present study, we determined hormonal changes during pregnancy and the estrous cycle in captive female wolf by measuring fecal steroids collected during the breeding season with high performance liquid chromatography （HPLC）. These biochemical analyses were validated using chemical devivatization and mass spectrometry, and interpreted along with the behavioral data. All four females undergoing estrus cycles were copulated with their partners and delivered pups successfully. We found that estradiol concen-trations were significantly higher during the estrus cycle than other stages （p0.01） and progesterone was also significantly increased throughout the pregnancy （p0.01）. These hormonal fluctuations demonstrated pregnancy-specific changes in the fecal progesterone and estradiol con-centrations. Patterns of fecal estradiol and progesterone concentrations during estrous cycles were similar to those reported for other canids.
