Equine stress responses to anaesthesia.

This research investigates the stress responses in horses when anaesthetized, even when no surgery is performed, revealing increased stress-related hormones and a need for more horse-friendly anesthesia techniques.

Study Overview

• The study was aimed at obtaining more information about how horses respond to anesthesia, considering the limited understanding on this topic to date. Specific attention was given to understanding the physiological reactions, including changes to various hormones and substances in the bloodstream.
• The investigation involved six ponies which were anesthetized for a duration of two hours using halothane, a commonly used anesthetic. No surgical procedure was involved during this anesthesia.
• The assessment of the stress response was done by measuring plasma concentrations of glucose, lactate, cortisol, non-esterified fatty acids, insulin, catecholamines (also known as stress hormones), and adrenocorticotropic hormone (ACTH, a hormone which stimulates the adrenal glands, connecting with stress responses).

Comparison and Results

• This was a controlled experiment and the results were compared with the same group of ponies that remained conscious over the equivalent time period on a separate day. The ponies were not subjected to any other experimental variable during this time.
• Anesthesia led to an increased concentration of glucose, lactate, cortisol, and ACTH in the ponies’ bloodstream, as well as a decrease in the insulin concentration.
• Interestingly, repeating the procedure 18 months later with the same group of ponies resulted in the same response. This reinforces the reliability of the study findings about how the use of anesthesia alone causes a significant stress response in horses.

Significance and Suggestions

• The research signifies that the use of halothane and possibly similar anesthesia methods cause considerable stress in horses, even when no surgical intervention is in place. This is a significant concern for equine health and welfare and suggests that the anesthesia techniques commonly used in veterinary medicine may need reassessment and modification with respect to this species.
• The authors thus advocate for exploration of more ‘benign’ or gentle anesthesia techniques, which might minimize the stress response in horses, improving their well-being during and after such procedures.