Polina S. Klyuchnikova

Research on endocrine patterns associated with reproduction and lactation in felids has focused mainly on rare or endangered species and remains limited in the domestic cat (Felis catus). Using a non-invasive longitudinal approach, we measured faecal glucocorticoid, progesterone, and testosterone metabolites (fGCm, fPm, and fTm) in nine females before mating and during three months of lactation, examining associations with litter characteristics and kitten survival. Lactational concentrations were expressed relative to each female’s median baseline, while baseline concentrations were analysed separately. Relative fGCm concentrations were negatively associated with the number of surviving kittens but not with litter losses. Relative fPm concentrations were positively associated with both fGCm and fTm, whereas the fGCm–fTm relationship did not reach statistical significance. Relative fPm concentrations were lower in the third than in the first month of lactation, while fTm showed a similar decreasing tendency. Baseline fGCm and fPm were not associated with reproductive parameters. Median baseline fTm showed a negative, non-significant relationship with first-month kitten survival. These findings indicate distinct temporal patterns and associations among steroid metabolites, while the relationship between baseline fTm and kitten survival requires validation in larger datasets.

Hair can be a useful matrix to examine the hormonal status of an animal, although it is difficult to correlate the results to a specific time point. The aim of this study was to evaluate seasonal changes in cortisol and testosterone levels in the hair of four feline species (lynx, Lynx lynx, n = 8; Amur wildcat, Prionailurus bengalensis euptilurus, n = 8; caracal, Caracal caracal, n = 6 and domestic cat, Felis catus, n = 17) with different breeding strategies. Animals of both sexes were sampled over the year, once per season (every three months), and the concentrations of hair testosterone and cortisol were measured by EIA. Both hormones showed annual dynamic changes, which coincided with the reproductive seasonality of the studied species. Sexual differences in testosterone level were found only during the mating season (spring for lynx and Amur wildcats, spring–summer for domestic cats), when testosterone levels were higher in males than in females. Cortisol levels were higher in males than in females in domestic cats and Amur wildcat, but also only during the mating season. Seasonal increases in testosterone were observed in three seasonal breeders (lynx, Amur wildcat and domestic cat) but not in caracal, which had high testosterone levels over the whole year. In lynx and Amur wildcat, it decreased sharply in the summer. Cortisol levels increased during the mating period in domestic cat males and lynx of both sexes; in caracal, an increase in cortisol was related to the transfer of animals to smaller winter cages. Measurements of steroids in hair can provide a reliable method for evaluating the reproductive status and the activity of the hypothalamus–pituitary–adrenal axis in several felid species.