Arterial ovarian blood flow in the periovulatory period of GnRH-induced and spontaneous estrous cycles of bitches.

The aim of this study was to compare arterial blood flow determined by repeated Doppler sonographic examinations in the periovulatory period in GnRH-induced and spontaneous estrous cycles of bitches. The study was performed on 10 bitches with GnRH agonist implant-induced estrus (Suprelorin containing 4.7 mg deslorelin), and 10 bitches with spontaneous estrus (group B), which served as a control. Pulsed-wave Doppler ultrasonography was performed daily from the beginning of proestrus until early metestrus. The ovarian blood flow parameters in the left and right ovarian arteries, including systolic peak velocity (SPV), end diastolic velocity (EDV) and resistance index (RI), were measured. Obtained outcomes from the period of three days before ovulation (Days -3, -2, -1), ovulation (day 0) and three days after ovulation (Days +1, +2, +3) were evaluated statistically. There were no differences between blood flow variables in the bitches with spontaneous and induced cycles recorded on the same day. The values of SPV and EDV were higher (p < 0.05) on days -1, 0, +1, +2 and + 3 than the velocimetric variables collected on days -3 and -2. Then, a significant increase in blood flow was detected one day before ovulation and was continued during next 3 days (p < 0.05). In contrast, the mean RI values remained constant during the entire experiment or even showed a slight declining trend in both groups (p > 0.05). We concluded that arterial blood flow measured around ovulation does not allow for precise detection of exact ovulation time in bitches in induced and spontaneous cycles.