Oxidative stress as an etiology of respiratory alterations in canine neonates under different degrees of meconium in the amniotic fluid

• Grant number: 24/16935-3
• Support Opportunities: Scholarships in Brazil - Scientific Initiation
• Effective date (Start): December 01, 2024
• Effective date (End): November 30, 2025
• Field of knowledge: Agronomical Sciences - Veterinary Medicine - Animal Reproduction
• Principal Investigator: Camila Infantosi Vannucchi
• Grantee: Beatriz Caraciolo Evangelista
• Host Institution: Faculdade de Medicina Veterinária e Zootecnia (FMVZ). Universidade de São Paulo (USP). São Paulo , SP, Brazil

Abstract

Meconium staining of amniotic fluid occurs when there is early elimination of meconium (gastrointestinal contents of the fetus) in response to some situation of fetal stress. Contamination of amniotic fluid by meconium is the main etiology of Meconium Aspiration Syndrome, described in humans, which results in severe respiratory impairment, respiratory distress, hypoxemia and neonatal acidosis, which vary according to the degree of meconium staining. The presence of meconium stained amniotic fluid in the fetal lung structure is responsible for significant lung injuries, including local oxidative stress, constituting an important cause of neonatal morbidity. Despite its clinical importance, there are no detailed descriptions in the literature about the impacts of meconium staining of amniotic fluid on the respiratory development of canine neonates, which makes it difficult to direct care for the neonate and reduces the chances of successful treatment. Thus, this research aims to evaluate the influence of different degrees of meconium on oxidative stress and antioxidant profile of amniotic fluid and its correlation with possible pulmonary alterations in the fetal-neonatal transition period of dogs. For this purpose, 30 fetuses and neonates will be selected and allocated into 4 experimental groups according to the intensity of meconium present in the amniotic fluid: Absent Meconium Group (n=15), Mild Meconium Group (n=5), Moderate Meconium Group (n=5) and Intense Meconium Group (n=5). During cesarean delivery, amniotic fluid samples will be collected to evaluate the antioxidant profile by measuring the enzymes superoxide dismutase (SOD), glutathione peroxidase (GPx) and glutathione reductase (GSH) activity and evaluating oxidative stress by lipid and protein peroxidation. At birth, at 5 min and 60 min of life, neonates will be assessed for vitality score, peripheral oxygen saturation and chest ultrasound, performed in B-mode to assess the degree of lung aeration. Lung ultrasound will use a semiquantitative score for the presence and quantity of B-lines and A-lines, in addition to pleural sliding and regularity of the pleural line. The measurement of the mean gray scale of the lung content of the ultrasound images will be performed using the image-J software. Data will be analyzed by orthogonal contrast and Pearson or Spearman correlation analysis, considering P<0.05.