No abstract

Neonatal immediate adaptation to extrauterine life depends mainly on adequate lung function, which is under the influence of previous fetal maturation and obstetrical condition, both acting to stimulate the efficient liquid removal from the pulmonary parenchyma during the immediate transition period. The objective of the present study is to identify chest radiographic changes of neonatal calves born under the influence of different duration of calving and obstetric assistance and correlate with clinical analysis and blood acid-base balance. Experimental groups were determined according to the duration of calving: 2 h (n  =  16), 2–4 h (n  =  16) and >4 h (n  =  12), and additionally by two sub-groups: no-intervention calving (n  =  22) and intervention calving (n  =  22). Neonatal calves were evaluated for heart and respiratory rate at birth, 5 min, every 10 min until 90 min. Arterial acid-base balance was determined immediately after calving and thoracic radiographs were made at 10 min of life. Lung radiopacity was higher in the 2–4 hr Group compared to the 2 hr Group. When calving duration was greater than 4 hours, a significant respiratory depression was observed. Calving greater than 2 hours slower neonatal pulmonary clearance, 100% and 91.6% of the calves born in the 2–4 hr and >4 hr Groups, respectively, had mild to moderate lung parenchyma opacity. There was a positive correlation between lung radiographic changes and blood TCO2 and negative correlation between pulmonary opacity score and blood PaO2 and SO2. Hence, it is possible to infer that neonatal hypoxia during prolonged calving has an imperative influence on pulmonary fluid absorption in calves. In conclusion, calving greater than 2 hours impacts pulmonary function at birth, leading to altered lung gas exchange, pulmonary clearance, cardiac and respiratory pattern. Conversely, obstetric intervention when calving has duration greater than 4 hours is beneficial for neonatal oxygenation.

Ultrasonographic examination of pregnant ewes can enable the identification of perinatal abnormalities and establish prenatal assistance responsible for minimizing morbidity and perinatal mortality. Therefore, we aimed to evaluate the feasibility of a fetal biometric analysis by ultrasonography to predict neonatal vitality and lamb growth during the first month of life. A longitudinal study was conducted with 13 healthy ewes, subjected to ultrasonographic examination every 15 days from 60 th day of pregnancy until lambing, evaluating thoracic diameter, abdominal diameter, biparietal diameter, humerus, femur and placentome length. At birth, 22 lambs were assessed through Apgar score at 5 minutes and after 1 hour. Measurement of body weight was also carried out immediately at birth and weekly during 30 days after birth. Thoracic diameter showed a significant increase between 91-105 days and 121-135 days. Conversely, abdominal diameter had a progressive growth until 106-120 days, and then, a steady development was observed. Biparietal diameter showed progressive growth only towards days 91 and 105. For the humerus length, we verified a significant increase between 106-120 days and 121-135 days, remaining unaltered onwards; while femur length continued to grow until lambing. The linear regression analysis between birth weight and biparietal diameter at 60-75 days was high (R 2 =0.96; P<0.0001; coefficient of variability of 3.3%). In conclusion, ultrasonographic analysis of fetal biparietal diameter at mid-pregnancy can be used as a predictor of lamb weight at birth. Moreover, assessment of femur length at final pregnancy can be employed for fetal and neonatal development estimation.

During pregnancy, fetal lambs are exposed to low oxygen tension. Thus, an effective antioxidant mechanism is partially developed which sensitizes fetus to oxidative stress. Consequently, term and preterm neonates are susceptible to molecular and cellular injury caused by oxygen species (ROS). This study aimed to evaluate the development of antioxidant enzymes and oxidative profile of preterm (135 days of pregnancy) and term (145 days of pregnancy) neonatal lambs, correlating with clinical analysis. Preterm lambs had significantly (P ≤ 0.05) lower score of vitality (4.00 ± 1.10), bradycardia (99 ± 34 bpm) and bradypnea (13 ± 10 mpm). However, both groups were normothermic and euglycemic. Preterm group had low blood pH (7.07 ± 0.10) and both groups had hypercapnia, more severe in preterm group (85.52 ± 18.65 mmHg). In addition, premature newborns had lower pO 2 (10.67 ± 5.65 mmHg) and SO 2 (6.17 ± 5.85%) values. No significant difference (P ≥ 0.05) on antioxidant enzymes and oxidative stress were verified among experimental groups, although glutathione peroxidase negatively correlated with Apgar score, heart rate, SO 2 and pO 2 . Our data show that preterm neonates are less adapted to the odds of labor and to overcome the immediate changes of extra-uterine life. Furthermore, we verified an influence of glutathione peroxidase in controlling oxidative stress, which highlights mature enzymatic mechanisms of cell redox, even in premature lambs.

Placenta is considered an important endocrine organ during gestation, as well as can also serve as a target organ for sex steroids and pituitary hormones, mainly for the cascade of events that trigger parturition. In order to initiate studies on the canine placental endocrinology regarding estrogen and oxytocin, the present study verified the correlation among the Estrogen Receptor alpha (ERα) and Oxytocin Receptor (OTR) gene expression in the placenta tissue with the serum concentrations of their respective hormones (estrogen and oxytocin) during canine pregnancy and parturition. Real-time PCR was performed to quantify the levels of ERα mRNA and OTR mRNA in the placenta tissue of bitches (n=46) during Early (up to 20 days of gestation; n=11), Mid (20 to 40 days; n=12) and Late Pregnancy (40 to 60 days; n=12) and Parturition (first stage of labor; n=11). Serum samples were collected for the evaluation of estradiol and oxytocin (OT) concentrations by radioimmunoassay. Placental ERα mRNA expression showed a progressive decrease along gestation towards parturition. Placental ERα mRNA expression was significantly higher until 40 days of pregnancy in comparison to Parturition. Regarding OTR mRNA expression, no statistical differences among groups were verified. The Parturition Group presented higher estrogen concentrations in relation to Early and Mid Pregnancy Groups. Serum oxytocin concentrations were not different among pregnancy and parturition. During late pregnancy, a positive correlation was observed between placental ERα mRNA and oxytocin serum concentration. In conclusion, ERα mRNA in the canine placental tissue varies in a time-dependent manner, especially during the period of placentation and placental growth. Conversely, serum estrogen concentrations do not regulate directly the changes in OT receptors expression in the canine placenta.