Meconium Aspiration Syndrome in Animal Models: Inflammatory Process, Apoptosis, and Surfactant Inactivation

Abstract

Meconium Aspiration Syndrome is a condition that causes respiratory distress in newborns due to occlusion and airway inflammation, and surfactant inactivation by meconium. This condition has been described in animal species such as canids, sheep, cattle, horses, pigs, and marine mammals. In its pathogenesis, the pulmonary epithelium activates a limited inflammatory response initiated by cytokines causing leukocyte chemotaxis, inhibition of phagocytosis, and pathogen destruction. Likewise, cytokines release participates in the apoptosis processes of pneumocytes due to the interaction of angiotensin with cytokines and the caspase pathway. Due to these reactions, the prevalent signs are lung injury, hypoxia, acidosis, and pneumonia with susceptibility to infection. Given the importance of the pathophysiological mechanism of meconium aspiration syndrome, this review aims to discuss the relevance of the syndrome in veterinary medicine. The inflammatory processes caused by meconium aspiration in animal models will be analyzed, and the cellular apoptosis and biochemical processes of pulmonary surfactant inactivation will be discussed.

Importance of Monitoring Fetal and Neonatal Vitality in Bovine Practices

“…Currently, the main emphasis in obstetrical assistance must be placed on the prevention of asphyxia due to the lack of instruments that can reliably clear respiratory passages, maintain this state, and perform artificial respiration, as well as the insufficient competency-based skill of calving assistants to manage artificial respiration in the field. Although a calf aspirator/resuscitator for the suction of bronchial secretions is already available in bovine practice [ 1 , 117 ], intrauterine hypoxia during obstetrical assistance may develop depending on the degree of metabolic acidosis, organ injuries (hemorrhage), or meconium aspiration, which may increase the prevalence of neonatal mortality [ 118 , 119 ].…”

Strategies and Mechanisms of Thermal Compensation in Newborn Water Buffaloes

“…Likewise, other factors can be mentioned, such as the presence of amniotic fluid on the skin, since this fluid can lead to heat loss due to its evaporation, and it covering large areas of the body surface can significantly reduce the temperature of the individual. To all of the above we add the aspiration of fluid in the respiratory tract that limits the animal's respiration [1,57,58], which could make the mechanisms of temperature compensation less efficient due to the limitation of critical energetic substrates such as oxygen [43]. However, to clearly understand the influence of these factors, they must be discussed individually.…”

Assessment of Vitality, Blood Profile, and Degree of Meconium Staining on the Skin in Newborn Dogs According to Its Birth Weight

“…Newborns exposed to meconium aspiration develop Meconium Aspiration Syndrome(MAS) [ 31 ]. MAS increases neonatal mortality due to hypoxemia, acidosis, respiratory distress [ 31 , 32 , 33 ], and pulmonary edema due to the proinflammatory mediators contained in meconium [ 34 ]. MAS has been reported to occur in diverse species; for example, in puppies, the reported mortality from MAS can reach 1–3% [ 35 ].…”

“…MAS has been reported to occur in diverse species; for example, in puppies, the reported mortality from MAS can reach 1–3% [ 35 ]. Various articles explain the pathophysiology of MAS; however, Swarman et al [ 36 ], Martínez-Burnes et al [ 31 ], and Mota-Rojas et al [ 33 ] describe the association between MAS, airway obstruction, and fetal hypoxia, this being one of the most critical factors that can cause a loss of vitality in newborns.…”