Comparative effects of ketamine / xylazine and ketamine / medetomidine anesthesia for ovariectomy in Wistar rats

MARURI, ALEJANDRO; SANTONJA, FLORENCIA ELEONORA; VILLA, IVANA; ZÁRATE, SANDRA; GULIN, ERNESTO

Mar del Plata

Congreso; Reunión Sociedades de Biociencias; 2023

SAIC-AAFE-AB-AACyTAL

Refinement involves modifications of husbandry or experimental procedures that minimize or eliminate animals’ pain and distress and improve their welfare. Balanced anesthesia and analgesia promoterefinement in surgical procedures. This study aims to compare ketamine 75 mg/kg + xylazine 10 mg/kg (KX) combination with ketamine 60 mg/kg + medetomidine 0.25 mg/kg (KM) in clinical monitoring and time-related anesthesia parameters for ovariectomy in Wistar rats. Protocol was approved by the Faculty of Medicine IACUC (RESCD-2022-3545). Twenty-four three-month-old female Wistar rats were submitted to ovariectomy by dorsal approach. The anesthetic combination was assigned randomly, and treatment was blinded for the anesthesiologists up to data analysis. The complete protocol included pre-surgical meloxicam (1 mg/kg; sc) and yohimbine (2.1 mg/kg; ip) when procedure finished. Thermal support and ophthalmic ointment were provided during surgery and recovery. After anesthesia administration, the animal was observed up to the loss-of-righting reflex (LRR) and the loss-of-pedal withdrawal reflex (PWR-). The PWR was tested until returned positive. Time points for consciousness and exploratory behavior recovery was also recorded. Intra-surgical rectal temperature, respiratory rate and cardiacfrequency were recorded. The time to achieve LRR was not significantly different between anesthetic combinations, but PWR was significantly faster for KM than KX combination (p=0.0173).Time to recover PWR, consciousness and exploratory behavior was significantly longer in rats receiving KM than those who received KX (p˂0.05). Clinical parameters did not significantly differ betweentreatments. One rat from each anesthesia protocol did not recover from the procedure. KM combination resulted in a safe anesthesia surgical plane at lower doses than classical KX protocol. Still, considering the prolonged recovery times, other dosage schemes should be explored until it becomes a superior anesthetic option for ovariectomy by dorsal approach in rats.