Emergency C-section and pre-natal maternal corticosteroid therapy: Three cases in pre-term brachycephalic dogs

Introduction: C-section performed before 62 days post LH surge is associated with a high risk of neonatal mortality due to fetal immaturity. Among other factors, increase of cortisol concentrations pre-partum plays an important role in final development of fetal pulmonary, renal, liver and gastro-intestinal systems (1). Pre-natal corticosteroid therapy has been used since 1972 in human medicine to prevent or, at least to reduce, respiratory complications in pre-term infants. This treatment is associated with a significant reduction of morbidity and mortality resulting from Neonatal Respiratory Distress Syndrome (2). Regazzi et al, Zaremba et al and Rider et al have confirmed the same results in dogs, calves and rabbits. Foetal lung development can be divided in five phases: embryonary, pseudoglandular, canalicular, saccular and alveolar. Pulmonary surfactant is secreted by pneumocytes II during the saccular phase. In 2009, Sipriani et al studied the development of the pulmonary structure throughout pregnancy in dogs. They reported that the saccular phase begins at the earliest 57 days post fertilization; thereby underlying the non-viability of younger puppies. Here we describe three cases of pre-term C-sections with pre-natal corticosteroid therapy.
Clinical cases: Two English Bulldogs and one Chihuahua underwent emergency C-sections. The three dogs had been trans-cervically inseminated once with fresh semen. They were followed during the estrus cycle, by vaginal smear and progesterone (P4) assay. Abdominal ultrasound with measurement of the inner chorionic cavity confirmed that the day of fertilization matched with the day of insemination (3). The two Bulldogs and the Chihuahua were presented for anorexia, dyspnea and exhaustion 56 days and 54 days post insemination respectively. Progesterone levels were around 10 ng/ml. The 3 dogs underwent the same surgical and anesthetic protocol. Two hours prior to surgery: perfusion with Hartmann + Glucose 5% solution, injection of prednisolone IM (0.5mg/kg), metoclopramide SC (0.5mg/kg) and amoxicillin clavulanic acid SC (8.75 mg/kg). Induction was achieved with dexmedetomidine (375μg/m2) and alfaxan IV (0,2mg/kg) maintenance with Isoflurane. The linea alba was locally anesthetized with lidocaine. Methadone (0.1 mg/kg) was administered IV at the time of delivery and again upon waking. The first Bulldog gave birth to 8 puppies: 3 had a cleft palate and were euthanized. One died after 4 days from respiratory distress. The four remaining ones survived. The second Bulldog delivered 10 puppies: 1 water puppy and 1 with cleft palate that were euthanized, 2 mummies. Out of the 6 other puppies only one died at 15 days from respiratory distress. The Chihuahua gave birth to 3 puppies who survived without complication despite their high degree of immaturity (hairless) and were sent back home.
Discussion: Pre-natal corticosteroid therapy has been shown to improve neonatal viability in several studies. Betamethasone injected 2 days before surgery has been proposed as the treatment of choice. However, Vannuchi et al reported in 2012 a suppression of the fetal and maternal adrenal cortex as well as a premature labor with an administration of betamethasone at 0.5mg/kg. Maternal treatment with prednisolone two hours before surgery should be investigated in order to measure its impact on the fetal and maternal cortisol levels in addition to its effect on surfactant production. Most studies on pre-natal corticosteroid therapy in dogs define the prematurity of the fetuses based on progesterone levels, the predicted LH surge and estimation of the ovulation 2 to 3 days post LH surge. In order to increase the accuracy of the gestational age, we combined progesterone levels, vaginal smear and US measurements. We report here three cases of emergency C-section with viable fetuses at 56 and 54 days post fertilization. We conclude that prednisolone injection 2 hours prior to surgery could represent an interesting protocol to increase neonatal viability and should be further investigated.
References: 1) Fowden et al. Proc Nutr Soc. 1998; 57: 113-122. 2) Regazzi et al., Theriogenology 2017; 97:179-185. 3) Lopate. Theriogenology. 2008; 70: 397-402.