The Importance of Preoperative Estrous Cycle Stage Assessment in Ovariohysterectomy: Clinical and Surgical Implications

The timing of ovariohysterectomy (OHE) in relation to the estrous cycle plays a crucial role in minimizing perioperative complications in bitches. This study aimed to evaluate whether preoperative vaginal cytology can effectively guide the timing of OHE and improve surgical outcomes. Fourteen bitches presented for elective OHE at MAKUVET Animal Hospital were divided into two groups. In Group I (n=7), OHE was performed during cytologically confirmed anestrus, whereas in Group II (n=7), surgery was performed without regard to estrous stage. Vaginal smears were evaluated using Papanicolaou staining, and intraoperative and postoperative complications were recorded. No complications were observed in Group I. In contrast, Group II presented minor intraoperative hemorrhage in two bitches and mammary gland development in one bitch during the postoperative period. Although statistical analysis did not reveal a significant difference between groups, clinical findings suggest that surgery during hormonally active phases, particularly diestrus, may predispose animals to adverse effects such as pseudopregnancy and mammary hypertrophy. These results support the routine use of vaginal cytology prior to OHE to identify the anestrus stage as the optimal surgical window. Integrating estrous cycle assessment into preoperative protocols may enhance surgical safety, reduce complications, and improve animal welfare.