Quantitative determination of progesterone (P4) in canine blood serum using an enzyme-linked fluorescence assay

Progesterone (P4) measurement in the peripheral blood is an objective parameter for determination of reproductive functions in the bitch. This study evaluates an enzyme-linked fluorescence assay (ELFA) (Biomerieux, France) for the determination of progesterone validated for use in human. The ELFA is to be performed on the MiniVidas automated analyser which provides quantitative results within 45 min. Blood samples from a total of 27 female dogs of different breeds were used. To test the correctness of the ELFA 15 blood samples with a range of 0.3-40.0 ng/ml were compared to a radioimmunoassay (RIA) validated in the dog. The values obtained with the MiniVidas showed a high agreement (mean deviation 15%), deviations were in both directions and the correlation coefficient was 0.989. The coefficient of correlation according to Passing-Bablok test was 0.995. The intra-assay reproducibility in the MiniVidas system was tested on five samples (mean values 61.8, 6.8, 51.4, 43.7 and 1.1 ng/ml). The coefficients of variation (CV; 10-12 replicates) were 3.4%, 6.7%, 2.6%, 3.1% and 25.4%, respectively. Four serum samples (mean value 47.0, 15.1, 49.1 and 4.0 ng/ml) from different bitches were assayed singly in 10 separate series to test the inter-assay variability. The corresponding CV was 2.1%, 2.2%, 3.1% and 4.3% respectively. Samples from three dogs were used to test the accuracy of the assay. These samples were diluted (1/2, 1/4, 1/8 and 1/16) with charcoal-stripped human serum (Biomerieux, France) and tested in three runs. The expected values were met in a range of 60-75%. Measurement of progesterone for the detection of ovulation as well as prediction of parturition provided meaningful results. As a conclusion the use of the MiniVidas system for determination of P4 in peripheral blood of the bitch provides rapid and reliable results.