Comparison of canine ovulation prediction methods by estradiol and progesterone

Abstract

The use of estradiol and progesterone value for canine ovulation predication has been previously reported. Here, we tried to compare each of these methods precisely for ovulation detection and seasonal accuracy also. Serum progesterone (P4) and estradiol (E2) level were employed for ovulation determination. The P4 and E2 level were measured by using ECLI (Electro Chemi Luminescence Immunoassay) system. For analysis, blood samples were collected from 30 estrus bitches in each group during pro-estrus and estrus period. We predicted 72 hours (3 days) as ovulation point with E2 peak and 6–15 ng/ml of P4, respectively. Furthermore, the oocytes were collected on the predicted ovulation day. We collected higher percentage of mature oocytes while using E2 (83.3%) as compared to P4 (53.3%). Alternatively, the P4 levels were checked at 72 hours after E2 peak which was found 4–28 ng/ml; much broader range than 6–15 ng/ml. Accuracy of P4 increased from spring (30.76%) to summer (47.92%) and decreased in autumn (37.50%) and winter (29.16%) gradually. Especially, E2 maintained about 50% to 65% whatever the season and temperature. Correlation analyze showed that dynamic of P4 accuracy highly correlated with environment temperate (Rp4=0.862) but E2 could not be affected by the temperature (RE2=0.199). In conclusion, we found that E2 peak method is more precise than that of P4 range, which deciphered the limitation of later method. Moreover, E2 method cannot be affected by measuring system as peak point is always same regardless of measured values in different machines or different environmental temperature. Therefore, we highly recommend the E2 method for ovulation determination in estrus bitches.