Effects of surgery on endocrine and metabolic responses to anaesthesia in horses and ponies.

This study investigates the impact of surgery on the hormonal and metabolic reactions to anesthesia in horses and ponies. The research indicates that while surgery does influence these responses, its additional effect is minor compared to the stress response already induced by halothane anaesthesia in Equidae.

Research Design

• The experimental subjects of this study were seven horses and eight ponies. Each of these animals was put under anaesthesia twice, with surgery being performed during one of these instances.
• To monitor the physiological responses to anaesthesia and surgery, a range of biological measures were taken. This included cardiorespiratory monitoring and blood sampling.
• Through blood sampling, the researchers measured cortisol, glucose, lactate, insulin, catecholamines, and non-esterified fatty acids (NEFA). Each of these substances is a marker for stress and metabolic responses in the body.

Key Findings

• Arterial hypotension, a condition defined by low blood pressure, developed in all the test subjects. However, this condition was more pronounced among those that underwent surgery. Similarly, the postoperative pulse rate was higher in the surgical groups.
• Levels of cortisol, a hormone released in response to stress, increased during anaesthesia in all test subjects. However, these levels remained high post-surgery.
• Another significant observation was the rise in lactate levels during anaesthesia across all subjects, with higher elevation during surgery. Lactate is a byproduct of anaerobic metabolism and high levels can indicate a stress response or metabolic dysregulation.
• Changes in glucose, insulin, and catecholamine levels were not significant during anaesthesia in horses, but there was a decrease in NEFA. In ponies, however, plasma glucose levels increased during anaesthesia and were more elevated in the non-surgical groups.
• The overall findings suggest that while there are physiological changes in response to anaesthesia and surgery, the additional stress caused by surgery when compared to anaesthesia alone is not significant.

Conclusions and Implications

• This research gives insights into the effects of surgery and anaesthesia on endocrine and metabolic responses in Equidae – a family of horses and ponies.
• The results reveal that anaesthesia with halothane provokes a notable stress response in horses and ponies, as reflected in biomarkers such as cortisol and lactate.
• However, the study also indicates that surgery does not add significantly more stress compared with the anaesthesia alone. This is important to consider when evaluating the overall risk and stress to the animal during surgical procedures.
• More research would be beneficial to further understand these responses and to develop anaesthetic practices that minimise the stress responses in horses and ponies.