Analysis of Testosterone and Cortisol Fecal Metabolites in Male Pallas’ Cats (Otocolobus manul) Housed Under Artificial Lighting Conditions
The Pallas’ cat (Otocolobus manul) is a small felid species indigenous to central Asia. Maintenance of this species in captivity is difficult because of chronic infection and reactivation with Toxoplasmosis gondii and feline herpesvirus 1.3 Pallas’ cat kittens in captivity experience high neonatal mortality from toxoplasmosis. Current research on this species at North Carolina State University College of Veterinary Medicine is focused on the creation of specific pathogen-free (SPF) kittens. Pallas’ cat breeding cycles are photoperiod dependent. Male cats experience significant weight gains, increased testosterone levels, and sperm production levels between December and March when the days begin to lengthen.4 Previous studies have demonstrated that artificial lighting conditions can cause abnormal reproductive cycles in captive female Pallas’ cats.2
In order to assess the impact of artificial lighting on reproductive cycling in male Pallas’ cats, an analysis of fecal androgen metabolites was conducted on four male Pallas’ cats housed under fluorescent light timed to match natural photoperiod. To evaluate baseline cortisol levels in captive male Pallas’ cats, assays for fecal cortisol metabolites were also conducted. Fecal samples were collected twice each week from each cat from November through June. Ethanol extraction and enzyme immunoassays (EIA) validated for this species were conducted to quantify testosterone and cortisol metabolites in the samples.1 Data were analyzed with logarithmic transformation and F tests based on analysis of variance.
The mean testosterone level of each cat was significantly higher from mid-January to mid-March. These results demonstrate that male Pallas’ cats maintain normal breeding cycles in artificial lighting conditions. Mean cortisol levels for each cat were evaluated for differences between the breeding season, mid-January to mid-March, and the nonbreeding season. The male paired with the female had a significantly higher cortisol level during the breeding season. Calculations of z values for cortisol were conducted to assess the number of samples that differed from the mean cortisol value for each cat. Only 16 of 207 z values from the four cats were greater than ±2, with three of those 16 z values greater than ±3.
These results demonstrate that male Pallas’ cats maintain a normal breeding season, previously established as January–April, when housed under artificial lighting conditions. While it is difficult to interpret the significance of fecal cortisol metabolites in captive wildlife as an indicator of chronic stress without reference values from free-ranging animals, the relative lack of cortisol values that vary from the mean suggests that these four males are adapted to their artificial environment. Further studies are needed to determine whether increases in cortisol in male Pallas’ cats paired with females during the breeding season are normal.
This research was supported by funding from the North Carolina Zoological Society. The authors would like to thank Disney’s Animal Kingdom for providing funds to support animal care and the fecal steroid assays, Dr. Barry Peters for technical support, and Erning Li for assistance with statistical analysis.
1. Brown J.L., K.A. Terio, and L.H. Graham. 1996. Fecal androgen metabolite analysis for non-invasive monitoring of testicular steroidogenic activity in felids. Zoo Biol. 15: 425–434.
2. Brown J.L., L.H. Graham, J.M. Wu, D. Collins, and W.F. Swanson. 2002. Reproductive endocrine responses to photoperiod and exogenous gonadotropins in the Pallas’ cat (Otocolobus manul). Zoo Biol. 21: 347–364.
3. Swanson W.F. 1999. Toxoplasmosis and neonatal mortality in Pallas’ cats: a survey of North American zoological institutions. Proc. Am. Assoc. Zoo Vet., Columbus, OH. Pp. 347–350.
4. Swanson W.F., J.L. Brown, and D.E. Wildt. 1996. Influence of seasonality on reproductive traits in the male Pallas’ cat (Felis manul) and implications for captive management. J. Zoo Wildl. Med. 27: 234–240.