Timing of elective cesarean section on biparietal ultrasonographic measurement in English Bulldogs

Among brachicephalic breeds, English Bulldogs are usually subjected to elective C-sections because of their typical morphological conformation, which predisposes to a high risk of dystocia. In this breed, an average of 8.5% perinatal mortality within the first 7 days of life has been reported (1). Among several factors affecting the postnatal survival (i.e. prolonged labor, dystocia, malformations etc.), the timing of elective C-section has a crucial role. In clinical practice, planned surgery is generally scheduled based on data derived from estrous monitoring, ultrasonographic fetal biometry, and progesterone determination at term. Concerning fetal biometry, a high accuracy of the predicted term is obtained when size-related fetal growth curves are available (2,4). In English Bulldogs, the disproportion between size and body weight and the occurrence of sporadic natural parturition (due to elective C-sections), hinder the definition of fetal growth curves based on actual parturition term. The aim of this study was to evaluate the effect on perinatal mortality of an elective C-section performed at different times from the parturition day predicted only by biparietal (BP) measurements (using fetal growth curves of medium sized bitches). Litter size and perinatal mortality in 25 English Bulldogs subjected to C-section were retrospectively evaluated. Bitches were grouped according to the time interval between C-section and the day of parturition term estimated by BP measurements (2). BP was visualised on a longitudinal scan of a fetal head and the distance between parietal bones was recorded. The BP measurements were performed between week 5 and 8 of gestation (3): ≤ 2 days (group A, n. 17) or 3 days (group B, n. 8). Data were statistically analyzed by Chi-Square and the OR was calculated. Neonatal loss occurred in a significant higher proportions of litters of group B compared to group A (87.5% vs 17.7%, p<0.001). Out of overall 147 puppies, perinatal mortality was also higher (p<0.001) in group B (32.7%, 18/55) compared to group A (5.4%, 5/92): OR between groups was 8.5 (p<0.001). Present results demonstrate that in English Bulldogs the elective C-section can be safely performed when based on the date of whelping estimated by ultrasonographic BP growth curves of medium size bitches. A eight times greater risk for perinatal mortality occurred when the surgery was performed 3 days before the predicted parturition day, instead of within 2 days in which the mortality resulted lower than the rate of 8.5% expected in this brachicephalic breed (1). [1] Tønnessen R, Sverdrup Borge K, Nødtvedt A, et al. Canine perinatal mortality: A cohort study of 224 breeds. Theriogenology 2012;77:1788–1801. [2] Luvoni GC, Grioni A Determination of gestational age in medium and small size bitches using ultrasonographic fetal measurements. J Small Anim Pract 2000;41:292–294. [3] Beccaglia M, Luvoni GC Prediction of parturition in dogs and cats: accuracy at different gestational ages. Reprod Domest Anim 2012;47:194-196. [4] Alonge S, Beccaglia M, Melandri M, et al. Prediction of whelping date in large and giant canine breeds by ultrasonography foetal biometry. J Small Anim Pract 2016;57:479-483.