Endocrine Characteristics of Female Pallas’ Cats Maintained Under Artificial Lighting
The Pallas’ cat (Otocolobus manul) is a small felid endemic to Central Asia that is threatened with extinction. They have a pronounced reproductive seasonality, controlled primarily by circannual variation in photoperiod. Previous studies have demonstrated that artificial lighting conditions can cause abnormal reproductive cycles in captive female Pallas’ cats.1 The Pallas’ cat colony at NCSU is maintained under fluorescent light timed to simulate natural photoperiods. An analysis of fecal steroid metabolites was conducted in three female Pallas’ cats to evaluate whether their reproductive cycles mimic that of Pallas’ cats exposed to natural environmental lighting conditions. Fecal samples were collected two to three times per week throughout the breeding season (January–April) during the years 2002 and 2003. Ethanol extraction and enzyme immunoassays (EIA) were conducted to quantify the concentration of progesterone, estrogen, and cortisol metabolites in the fecal samples. Female 1 had fecal progestogen levels of 0.57±0.28 µg/g in 2002 and 7.16±5.39 µg/g in 2003. She was anovulatory in 2002 and was treated with exogenous gonadotropins in 2003. Corresponding baseline fecal estrogens were 262.9±45.8 ng/g and 337.7±78.1 ng/g. Anestrous estrogen levels in this species were previously reported as 50.2±8.5 ng/g.1 Female 2, who became pregnant during both the 2002 and 2003 seasons, respectively had pre-pregnancy progestogen levels of 0.42±0.10 and 0.45±0.19 µg/g. Pregnancy fecal progestogen levels were 20.76±10.86 µg/g in 2002 and 15.68±10.28 µg/g in 2003. Baseline estrogen values were 201.0±54.8 ng/g in 2002 and 162.4±46.0 ng/g in 2003. Female 3 came to the colony in January 2003 from a 12-hour light cycle. Progestogen levels were 4.94±8.24 µg/g, and baseline estrogen levels were 145.0±23.4 ng/g. Both females 1 and 3 experienced pseudopregnancies during the 2003 season, but female 3 did not exhibit luteal activity until late April, presumably as a result of a delay in acclimating to a simulated natural photoperiod. Cortisol metabolite levels varied among individuals, but the variation was not substantial, and the females appeared well adapted to their artificial environment. When compared to previous data, the Pallas’ cat colony at NCSU displayed a seasonal estrus similar to other Pallas’ cats under normal environmental light stimulation.