Preovulatory follicular stasis, or dystocia, is a significant cause of disease in female reptiles that can result in the death of the animal, or in loss of reproductive potential following surgical intervention. The aim of this study is to characterize the hormonal patterns associated with the reproductive cycle in female veiled chameleons to gain a better understanding of the basic reproductive biology of this species.
Fecal samples from 29 female veiled chameleons were analyzed for estrogen, progesterone, and testosterone over three reproductive cycles. Hormone patterns were correlated with changes in skin colour and behaviour indicative of distinct cycle stages. A subset of animals also had ovarian activity assessed by MRI every 2 weeks.
Enzyme immuno-assays (EIA) for estrogen (E2), progesterone (P4), and testosterone have been validated for fecal analysis in veiled chameleons. Preliminary results for estrogen on three control animals revealed baseline levels between 500 and 1000 ng/g dry feces and significant peaks reaching 4000 ng/g and lasting 3–4 weeks. Current results suggest correlations between estrogen levels, skin color changes, and ovarian activity.
Minimal work has been done to date using fecal hormone analysis in reptiles,1,2 and it is believed that this is the first study to validate the use of EIA for fecal reproductive hormones in a reptile species. This non-invasive monitoring technique will be a valuable tool for the proper assessment and manipulation of reproductive function in the veiled chameleon and potentially other reptile species.
The authors thank the Toronto Zoo Foundation, the Endangered Species Fund, and the Pet Trust for funding this research. Special thanks go out to Jane Sykes and Matheson Boulevard Veterinary Services for providing the MRI imaging and Paula Mackie for assistance with the endocrine analyses. The authors also wish to acknowledge the support of Dale DeNardo, Rebecca Spindler, and Andrew Lentini.
1. Casares, M. 1995. Untersuchungen zum Fortpflanzungsgeschehen bei Riesenschildkroeten (Geochelone elephantopus und G. gigantea) und Landschildkroeten (Testudo graeca und T. hermanni) anhand von Ultraschalldiagnostik und Steroidanalysen im Kot. Zool. Garten N. F. 65: 50–76.
2. Rittenhouse, C. D., J. J. Millspaugh, B. E. Washburn, and M. W. Hubbard. 2005. Effects of radiotransmitters on fecal glucocorticoid metabolite levels of three-toed box turtles in captivity. Wildl. Soc B. 33: 706–713.