Maintenance of Anesthesia Through Intravenous Constant Rate Infusion of Ketamine–xylazine in New Zealand White Rabbits

Objective: To evaluate the efficacy of intravenous constant rate infusion (CRI) of three different doses of a Ketamine–Xylazine (KX) combination in maintaining anesthesia and to explore its application in end-to-end intestinal anastomosis in rabbits. Study design: Prospective, randomized, blinded trial. Animals: Seventeen healthy female New Zealand white rabbits weighing 3.2 ± 0.1[Formula: see text]kg. Methods: Seven rabbits were induced anesthesia via intramuscular administration of a KX admixture (32.5[Formula: see text]mg kg[Formula: see text] + 6.5[Formula: see text]mg kg[Formula: see text]; 1× KX). A catheter was placed in the lateral ear vein within 10[Formula: see text]min of anesthesia induction. Each rabbit received all treatments in a random order for anesthesia maintenance through intravenous CRI of 0.5 ×, 0.75 × and 1 × doses of KX. The calculated dose of KX was diluted in 0.85% saline to a total volume of 40[Formula: see text]mL and administered over a 2[Formula: see text]h period. Cardiorespiratory parameters and anesthetic depth were recorded every 5[Formula: see text]min during this period. The 0.5 × KX regimen was further evaluated in other 10 rabbits undergoing end-to-end intestinal anastomosis. Results: After intramuscular anesthesia induction by 1 × KX, heart rate, respiratory rate and SpO 2 (peripheral oxygen saturation) all decreased significantly ([Formula: see text]). During the 2[Formula: see text]h CRI period, all three KX regimens maintained physiological parameters within acceptable ranges, except SpO 2 . SpO 2 did not exceed 90% until 60, 45 and 120 min in the 0.5 ×, 0.75 × and 1 × groups, respectively. All groups maintained a surgical depth of anesthesia effectively during the 2[Formula: see text]h CRI period. Ten surgical procedures were performed using the 0.5 × dose of KX maintained anesthesia for 125 ± 16[Formula: see text]min, and only one rabbit needed an additional dose at 104[Formula: see text]min. Conclusions and clinical relevance: Intravenous CRI of the KX combination appears to be an alternative approach for maintaining anesthesia in rabbits. Also, oxygen supplementation is required to improve hypoxemia during the anesthesia period.