Physiologic effects of anesthesia induced and maintained by intravenous administration of a climazolam-ketamine combination in ponies premedicated with acepromazine and xylazine.

This research aimed to understand the physiological and pharmacokinetic effects of using an infusion of climazolam and ketamine for maintaining anesthesia in ponies premedicated with acepromazine and xylazine. The study found that this technique did not significantly alter the ponies’ cardiovascular and respiratory functions and it largely maintained stable plasma cortisol, ACTH, and catecholamine concentrations, which indicate adrenal and pituitary gland function.

Methods

• Six healthy ponies were used in this experiment. They were first premedicated with acepromazine and xylazine.
• Anesthesia was induced with an intravenous administration of ketamine and climazolam two minutes after premedication.
• An infusion of climazolam and ketamine was used to keep the animals under anesthesia for a duration of 120 minutes.
• Oxygen was supplemented throughout the process. Sarmazenil, an antagonist of benzodiazepine, was administered after 20 minutes of stopping the infusion.
• The researchers carried out measurements of cardiovascular and respiratory functions before premedication, after premedication, and during anesthesia.
• Physiological parameters such as heart rate, respiratory rate, blood pressure, cardiac index, systemic vascular resistance, and the levels of oxygen and carbon dioxide in the arterial blood were all monitored and recorded.
• Plasma cortisol, ACTH (Adrenocorticotropic hormone), and catecholamine concentrations, which can help establish the functioning of adrenal and pituitary glands, were also monitored.
• The effectiveness and safety of the anesthesia technique was evaluated by calculating the kinetics of ketamine and climazolam based on their concentrations in the plasma.

Results

• Key physiological parameters such as heart rate, respiratory rate, arterial blood pressure, cardiac index, and systemic vascular resistance remained largely unchanged from their values prior to the administration of xylazine.
• The concentration of cortisol, a stress hormone, in the plasma reduced during anesthesia. However, the levels of ACTH and catecholamine did not show any significant changes.
• Following anesthesia, two of the ponies demonstrated some signs of excitement and unsteady movement (ataxia), indicating that recovery was not smooth in these instances.

Conclusions

• The combination of intravenous ketamine and climazolam infusion proved to be a viable method for maintaining anesthesia in ponies.
• However, the researchers noted that recovery from anesthesia was not ideal in two out of six ponies, suggesting that further studies might be needed to refine the process and enhance recovery post-anesthesia.