Fecal hormone patterns during non-ovulatory reproductive cycles in female veiled chameleons (Chamaeleo calyptratus)

Reproductive failure, in particular preovulatory stasis, is a common problem in captive female reptiles. For a better understanding of its pathogenesis, the patterns of fecal estradiol (E2), testosterone (T), progesterone (P) and their metabolites of 21 anovulatory female veiled chameleons, Chamaeleo calyptratus, were compared with those of 25 animals which ovulated during at least one cycle over the study period. Regular, cyclical hormone patterns, consisting of E2 peaks followed by simultaneous T and P peaks, were observed in all animals, regardless of whether oviposition occurred, indicating continuous ovarian activity. P concentrations were; however, significantly lower in animals undergoing anovulatory cycles. The average time period between the E2 and the T peak was 24.8 days, between the E2 and the P peak 26.5 days, and between the T and P peak 2.6 days. The mean length of reproductive cycles between two sequential ovulatory complexes (oviposition to oviposition) was 132.5 days (range 112–156 days). The results provide evidence that reproductive “failure” occurs more frequently than suspected with some females alternating between ovulatory and anovulatory cycles without any outward evidence of the variation in ovarian cycles. It is proposed that this may be related to physiological adaptation to adverse environmental conditions for breeding and that husbandry factors in captivity are primarily responsible for the progression from a physiological to pathological process.