The Effect of inhalation (Sevoflurane) anaesthesia on plasma levels of cortisol and vital signs during surgery in horses

Abstract

Cortisol is a steroid hormone and exerts a variety of systemic effects. Horses are often subjected to physiological stressors during races or competitions and frequently suffer from a wide range of diseases following surgery, which may also induce considerable stress. This study was designed to evaluate the effects of sevoflurane anaesthesia on plasma levels of cortisol and vital signs during and after surgery in horses. Fourteen clinically healthy adult horses (11 male and 3 female), weighing ~450 kg were used. All horses were initially sedated with xylazine (1.1 mg/kg BW). Five minutes later, ketamine (2.2 mg/kg BW) plus diazepam (0.05 mg/kg BW) were used for induction. After that a horse was intubated and inhalation anaesthesia with sevoflurane was induced. Vital signs including the heart rate, the respiratory rate, and the rectal temperature (RT) were recorded 30 min before operation -; after induction of sevoflurane, 15 min and 30 min; 60 min after the end of surgery. Blood was sampled at the above- mentioned times and analysed using the AIA-360 Automated Immunoassay Analyser for cortisol. A non-significant decreasing trend in RT was observed during the studied times. Significant changes in the heart rate and the respiratory rate (p > 0.05) were observed; in particular, at the time after operation (60 min) respiratory rates decreased significantly compared with the time before surgery (p < 0.05). Cortisol levels were found to be insignificantly decreasing during operation and increasing after.