Use of enzyme-immunoassay for oestradiol-17β 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 mul) was assayed for E-2 to estimate respective serum concentration. For P-4, each sample (10 mul) 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 less than or equal to 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 pg ml(-1) and 0.28 ng ml(-1), respectively. (C) 2002 Elsevier Science B.V. All rights reserved.