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

MARURI ALEJANDRO; SANTOJA FLORENCIA; VILLA IVANA; ZÁRATE SANDRA; GULIN ERNESTO

Congreso; Reunión Anual de Sociedades de Biociencias; 2023

Refinement involves modifications of husbandry or experimental procedures that minimize or eliminate animals' pain and distress and improve their welfare. Balanced anesthesia and analgesia promotes refinement 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 anaesthesia parameters for ovariectomy in Wistar rats. Protocol was approved by 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. Complete protocol included pre-surgical meloxicam (1 mg/kg; sc) and yohimbine (2.1 mg/kg; ip) when surgical procedure finished. Thermal support and ophthalmic ointment was 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. The time point at which rats recovered consciousness and exploratory behavior was also recorded. Intra-surgical rectal temperature, respiratory rate and cardiac frequency were recorded.Time to achieve LRR was not significant different between anesthetic combination but PWR- was significantly faster for (B) KM than KX (A) combination (p=0.0173). Time to recover PWR, consciousness and exploratory behavior was significantly longer in rats receiving (B) KM than those who received KX (A) (p˂0.05). Clinical parameters did not significantly differ between treatments. One rat from each anesthesia protocol did not recovered from the procedure.(B) KM combination resulted in good and safe anesthesia surgical plane at lower doses than classical KX (A) protocol, but 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.