Intrauterine hemodynamic, oxidative and immunological influence in puppies during the fetal-to-neonatal transition period

Abstract

Despite advances in veterinary medicine, neonatal mortality rates in dogs are still high, with the period of immediate neonatal adaptation or the fetal-neonatal transition considered the most critical for neonatal survival. The transition to extra uterine life requires rapid physiological adaptation of the neonate in order to assume functions previously performed by the placenta, such as pulmonary gas exchange, energy and immunological input. There are several causes of neonatal morbidity and mortality in dogs, however, it is possible to highlight, in particular, the different birth modes, with the use of elective cesarean section for the canine species being performed more frequently. the present study will be divided into 3 individualized experiments. In experiment 1, 10 pregnant bitches will be selected, from which 02 neonates will be studied, opting for those at the end of each uterine horn. According to the vitality score, neonates will be allocated into two experimental groups: High Neonatal Vitality Group (vitality score greater than or equal to 7, n = 10) and Low Neonatal Vitality Group (assigned vitality score less than 7, n = 10). During pregnancy, ultrasound assessment of the placenta, uterine and umbilical arteries will be performed, with the association of color Doppler for mapping the vessels, spectral Doppler for characterization of the waveform and power Doppler and ImageJ for quantification of the vascularized area. The placentas will be evaluated macroscopically by the general aspect, color, volume and measurement of the width and length of the zonary band. In addition, they will be prepared by systematic, random and uniform sampling for morphological and morphometric evaluation. Neonates will undergo clinical assessment at birth, 10 and 60 minutes after birth. Blood lactate will be determined between 1 and 5 minutes and within 6 hours of life and pulse oximetry evaluation will be performed shortly after birth, at 10 and 60 minutes of life. Mortality will be considered until the 14th day of life. For experiment 2, bitches and their puppies will constitute 4 experimental groups, according to the maternal GSH dose, administered prior to the surgical procedure (elective cesarean section): Control Group (without maternal treatment; n = 5); Group 5 (5mg/kg of GSH; n = 5); Group 10 (10mg/kg GSH; n = 5) and Group 20 (20mg/kg GSH; n = 5). The concentration of antioxidant enzymes and oxidative stress will be carried out in the blood serum of the mothers (pre-supplementation, trans-surgical and 1 hour after cesarean section), as well as in the neonates (at birth, 1, 6, 12 and 24 hours post- birth) and in the placentas. In addition, neonates will be evaluated for clinical analysis, lactatemia and peripheral oxygen saturation. In experiment 3, according to the obstetric condition, the females and their respective puppies will be allocated in two different experimental groups: vaginal delivery (n = 5) and elective term Cesarean section (n = 5). In addition, females will form two additional experimental groups, based on the moment of annual immunization in relation to childbirth: Recent Immunization Group (annual ethical vaccination less than 6 months from the date of delivery, n = 5) and Late Immunization Group (ethical vaccination more than 6 months from the date of delivery, n = 5). Colostrum samples will be collected aseptically after the end of the delivery or surgical procedure and at 6 am, 12 pm, 24 h and 48 h postpartum. For the evaluation of the passive immunity transference of canine neonates, blood samples will be obtained at those moments. Colostrum and neonatal blood serum samples will be used to measure immunoglobulin G by immunoenzyme and protein fractions by electrophoresis in cellulose acetate strips. Analyzes of the liver and glycemic profile of neonates will also be performed. (AU)