Use of enzyme-immunoassay for oestradiol-17beta and progesterone quantification in canine serum

The objective of this investigation was to develop and evaluate competitive inhibition-enzyme-immunoassays for canine serum oestradiol-17beta (E(2)) and progesterone (P(4)) quantification. Sera from 56 healthy bitches at various stages of oestrus cycle and pregnancy were tested. For E(2) measurement, each sample (0.4 ml) was extracted with diethyl ether and after solvent evaporation the resultant hormone was reconstituted to one-fifth of the original sample volume in aqueous buffer. Each reconstitute (30 microl) was assayed for E(2) to estimate respective serum concentration. For P(4), each sample (10 microl) was directly assayed without extraction. The classic cyclic hormonal pattern during the oestrus cycle of the bitch was observed. The brief, sharp dominance of E(2) during the follicular phase was followed by the long-lasting dominance of P(4) during the luteal phase (late oestrus, dioestrus or pregnancy). During the anoestrus phase both hormones were found at basal levels, with the exception of E(2) during late anoestrus which appeared to be rising. Both assays had acceptable specificity (cross-reactions < or =10%), precision (coefficient of variation (C.V.) < 7%) and accuracy (E(2) recovery: 97%; P(4) recovery: 104.7%). The sensitivity of E(2) and P(4) assay was 4 pgml(-1) and 0.28 ngml(-1), respectively.