Effect of postoperative xylazine administration on cardiopulmonary function and recovery quality after isoflurane anesthesia in horses.

The study explores the impact of administering different doses of the drug xylazine on the heart and lung functions of horses recovering from isoflurane anesthesia after arthroscopic surgery. The research found that lower doses result in quicker recovery times, though the quality of recovery is better when higher doses are administered.

Methodology

• The research was set up as a randomized, blinded, prospective, clinical study involving 20 horses.
• Following 3 hours of isoflurane anesthesia for arthroscopic surgery, the horses were split into two groups, each receiving different doses of xylazine intravenously during their recovery. Ten horses were given 0.25 mg/kg of xylazine (G25), while the remaining ten horses received 0.50 mg/kg of xylazine (G50).
• Vital signs and arterial blood samples were collected at several intervals during the recovery and post-sedation period, these being: before sedation (baseline), 5, 10, 20, 30, and 45 minutes after xylazine administration and another 30 minutes after standing.

Findings

• Horses in the G25 group were found to recover faster (mean of 33 minutes) than those in the G50 group (mean of 50 minutes). However, the recovery scores – a higher score indicating slower recovery – were better in the G50 group.
• Both groups experienced a significant decrease in arterial oxygen tension after receiving xylazine, indicating somewhat similar levels of hypoxemia (low oxygen level in the blood).
• The G25 group exhibited more attempts to stand but had a higher total recovery score, suggesting recovery quality was poorer than the G50 group.

Conclusions

• The study concluded that both doses of xylazine cause a moderate and transient occurrence of hypoxemia during the recovery period.
• Despite the longer recovery time, the higher dosage (0.50 mg/kg) of xylazine resulted in an improved quality of recovery from anesthesia compared to the lower dosage (0.25 mg/kg).