Faecal Steroid Metabolite Profiles and Reproductive Outcomes in Domestic Cat (Felis catus)

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.