Measurements of faecal oestradiol and progesterone in non-pregnant and pregnant domestic and exotic cats.

Faecal samples collected for variable periods from 12 animals and five species of cats were assayed for progesterone and oestradiol content by application of standard radioimmunoassays to aliquots (50 microliters) of methanol extracts (4 ml) of a mixture of 0.5 g sample, 0.5 ml water and 1 g aluminium oxide, following partitioning of the total extract with petroleum ether (3 ml), further dilution of assay aliquots and drying. Recoveries averaged 100 and 72% for oestradiol and progesterone, respectively. Results included increases in progesterone during luteal phases or pregnancies to 7688 ng g-1 (tiger, Panthera tigris), 2594 ng g-1 (lion, P. leo), 3000 ng g-1 (cheetah, Acinonyx jubatus) and 4915 ng g-1 (caracal, Felis caracal). Faecal oestradiol peaks near oestrus included 246 ng g-1 (tiger), 175 ng g-1 (lion) 190 ng g-1 (cheetah), 23 ng g-1 (caracal) and 190 ng g-1 (domestic cat, F. catus).