Predicting Whelping Day with Early Pregnancy Ultrasonography and Induction of Parturition using Mifepristone on the Expected Delivery Date in Bitches

Background: Inducing whelping in canines is becoming an accepted practice in obstetrical management to ensure safe pregnancy outcomes, although pinpointing the exact day for induction poses challenges. The precise timing of delivery is vital for foetal survival, as the placenta¢s nutrient supply cannot sustain the foetus beyond the expected delivery date (EDD). Additionally, completing the full gestation term is crucial for comprehensive organ development, especially for the maturation of the lungs. Methods: The present retrospective observational study was aimed to evaluate the accuracy of whelping day prediction by early pregnancy ultrasonography and to propose a viable whelping induction protocol with mifepristone on the EDD to improve the overall reproductive efficiency in canines. Result: Among 115 pregnancies in Group I, 69.57 % whelped exactly on the predicted day (±0), 93.04% whelped within ±1 day and 100% within ±2 days. In Group II, among 124 pregnancies 69.35% whelped on or before the EDD. Of the 38 bitches that did not whelp by the evening of EDD and which were given two doses of mifepristone, 73.68% whelped within 24 h. An additional 4 of the remaining 10 bitches whelped within 36 hours, resulting in an overall whelping induction response of 84.21 % and a cumulative vaginal birth rate of 95.16%. Six bitches (4.84%) required a caesarean section (CS) 36 h post-induction. The percentages of normal whelping, dystocia and CS varied significantly across Groups I, II and III, with Group II showing a significant reduction in dystocia and caesareans, supporting the hypothesis of inducing whelping with mifepristone on the prediction day to have more vaginal births. The percentage of animals that had CS in Groups I, II and III were 14.78, 4.84 and 56.67, respectively. The perinatal mortality rates were 14.83%, 10.47% and 25.15% in Groups I, II and III, respectively, with Group II showing significantly better puppy survivability.