Progesterone and oestradiol in canine plasma monitored by enhanced luminescence immunoassays

The Amerlite immunoassay system was evaluated for direct measurement of progesterone and oestradiol in canine plasma. The progesterone assay was evaluated without modification. To increase the sensitivity of the oestradiol assay, the horseradish peroxidase-labelled tracer was diluted 1:2 and the antiserum 1:10. Subsequently, the standards supplied in the kit were altered to produce a new standard curve. The dilution curves of canine plasma samples with high progesterone and oestradiol contents were parallel with the standard curves based on human serum. The relation between measurements of both hormones in canine plasma using established extraction methods as references and the Amerlite procedures were highly comparable, resulting in the linear regression equations y = 0.91x + 1.3 (progesterone, n = 100) and y = 0.79x + 0.9 (oestradiol, n = 84). However, for oestradiol the closest relation to the reference method was achieved when the incubation period was extended to 24 h at 4 degrees C. When measuring oestradiol and progesterone in canine sera during the oestrous cycle the hormone patterns were not influenced by the methods applied.