Aspiration pneumonitis (Mendelson's syndrome) as perianaesthetic complication occurring in two horses: A case report

No published reports on the occurrence of Mendelson's syndrome (pneumonitis caused by aspiration during anaesthesia) in horses were found in the literature. Although the peculiar anatomy of the equine stomach makes horses less prone than other species to regurgitate, gastric reflux may still occur in horses with colic under certain circumstances. The colic horses in this report had in common stomach impaction, abdominal distention and preanaesthetic placement of a nasogastric tube, which was not withdrawn prior to induction. In both cases, a significant volume of gastric reflux was noted pouring from the endotracheal tube during general anaesthesia for exploratory laparotomy. It was hypothesised that the cause of gastric reflux was the combination of increased intra-abdominal pressure and patency of the cardia, and that inhalation of gastric content occurred at induction, before tracheal intubation. Treatment, which failed to improve oxygenation, consisted of repositioning of the horses to facilitate passive drainage of gastric content from the airways, active suction through the endotracheal tubes, ventilation strategies, improvement of haemodynamics to increase the pulmonary perfusion, and administration of bronchodilators. One horse was subjected to euthanasia owing to poor prognosis. Aspiration pneumonitis should be regarded as a life-threatening, although rare, perianaesthetic complication in equine colic cases. Patency of the cardia and increased intra-abdominal pressure are possible predisposing factors. Partial or even total withdrawal of the nasogastric tube prior to anaesthetic induction and tracheal intubation performed with the horse positioned in sternal recumbency may be undertaken as preventive measures in patients at high risk of developing Mendelson's syndrome.