Reproductive hormonal patterns in pregnant, pseudopregnant and acyclic captive African wild dogs (Lycaon pictus).

African wild dogs are one of the most endangered canid species, with free-living populations declining as a consequence of habitat loss, disease and human conflict. Captive breeding is considered an important conservation strategy, but is hampered by a poor overall understanding of the reproductive biology of the species. To improve our basic knowledge, we studied hormone patterns in 15 female wild dogs using non-invasive faecal collections. By comparing longitudinal hormone profiles with behavioural and anatomical changes, females could be allocated among three reproductive classes: pregnant (n=1), pseudopregnant (n=9) and acyclic (n=4). We also monitored a single female in which contraception was induced with a deslorelin implant. Comparison of pseudopregnant and acyclic females showed that, in both classes, faecal oestradiol concentrations increased from anoestrus to pro-oestrus then declined into the oestrous and dioestrous phases. Progestagen concentrations rose steadily from anoestrus to the dioestrous phase in both pseudopregnant and acyclic females and, pseudopregnant females had significantly higher concentrations of progestagens than acyclic females in all phases of the oestrous cycle. Most females classed as pseudopregnant were found in female-only groups, suggesting that wild dogs are spontaneous ovulators. Furthermore, only one adult female did not ovulate, so suppression of reproduction in subordinates is likely to be behavioural rather than physiological.