Alfaxalone–Xylazine Anesthesia in Laboratory Mice (Mus musculus)

Abstract

Since its recent reformulation, alfaxalone has gained popularity as an injectable veterinary anesthetic, including promising studies demonstrating the use of alfaxalone-xylazine for anesthesia in mice. Here we sought to expand these studies by testing additional dose ranges, elaborating on physiologic monitoring, testing sex-and strain-associated differences, and evaluating efficacy during actual surgical conditions. C57BL/6J mice showed significant sex-associated differences in anesthetic sensitivity, with males requiring higher doses of alfaxalone (80-120 mg/kg IP alfaxalone with 10 mg/kg IP xylazine) than females (40-80 mg/kg IP alfaxalone with 10 mg/kg IP xylazine) to achieve a surgical plane of anesthesia. In addition, female outbred CD1 mice were less sensitive to alfaxalone than female inbred C57BL/6J mice. When used during actual surgery, alfaxalonexylazine administered intraperitoneally provided adequate anesthesia for a model of orthopedic surgery, whereas the same anesthetic regimen during laparotomy resulted in unacceptably high mortality; survival during laparotomy increased when drugs were administered subcutaneously. These results indicate that alfaxalone-xylazine may be a viable option for injectable surgical anesthesia in mice, although strain-and sex-associated differences and alternative routes of administration should be considered when optimizing the anesthetic regimen for specific experimental conditions.

Alfaxalone and Dexmedetomidine as an Alternative to Gas Anesthesia for Micro-CT Lung Imaging in a Bleomycin-Induced Pulmonary Fibrosis Murine Model

“…Alfaxalone, a neuroactive GABA A -agonist steroid can be considered a safe alternative to ketamine, since it is not a restricted agent and it is extensively employed in veterinary science for its safety profile. Alfaxalone induces anesthesia at relatively low doses when associated with analgesic drugs such as xylazine or dexmedetomidine, and it is often used to achieve a surgical plan of anesthesia in mice and rats ( 13 – 15 ). Dexmedetomidine is, indeed, a more potent α 2 -agonist compared to xylazine, which guarantees myorelaxation avoiding popcorn-like jumping induced by the only injection of Alfaxalone ( 14 ) and it may be likewise reversed by the antagonist administration (atipamezole hydrochloride) ( 16 ).…”

Evaluation of the Anesthetic Action of Alfaxalone in Chicks and Compared with Alfaxalone/ketamine or Alfaxalone/xylazine.

“…The central pharmacological activity of alfaxalone, ketamine, and xylazine varies considerably to the receptors and neurotransmitter systems concerned. Several studies explored the combined effects of alfaxalone-xylazine in rats [41] or alfaxalone-ketamine in rats [42] To minimize side effects and lower doses for improved anesthetic activity of medications. Alfaxalone could be coadministered with numerous anesthetics agent to yield effective balanced anesthesia .The combination of alfaxalone / xylazine produce a longer duration of anesthesia compared with alfaxalone alone and alfaxalone /ketamine but it produces a higher incidence of bradypnea in compared with alfaxalone alone and alfaxalone /ketamine groups, our finding is similar to the previous studies on the mice [41,42] , rats [43] , horses [44] , calves [45].…”

Gynura procumbens Root Extract Ameliorates Ischemia-Induced Neuronal Damage in the Hippocampal CA1 Region by Reducing Neuroinflammation

“…Ischemic surgery was conducted as described previously [ 32 , 33 ]. The animals were anesthetized with a mixture of 2.5% isoflurane (Hana Pharmaceutical Co., Ltd., Seoul, Korea) [ 38 , 39 ] in 33% oxygen and 67% nitrous oxide 1 h after the last vehicle or GPE-R treatment. The ventral neck region was shaved and a midline incision was made.…”

“…Following spontaneous motor activity observation, animals were deeply anesthetized with a mixture of alfaxalone (Alfaxan, 75 mg/kg; Careside, Seongnam, Korea) and xylazine (10 mg/kg; Bayer Korea, Seoul, Korea) 4 days after ischemia/reperfusion as a modified method [ 38 , 39 , 45 ] because neuronal cell death and subsequent glial activation was mainly detected in the hippocampal CA1 region 4 days after ischemia. Thereafter, brain samples were obtained by transcardial perfusion with 0.1 M phosphate-buffered saline (pH 7.4), followed by 4% paraformaldehyde in 0.1 M phosphate-buffer (pH 7.4), as described previously [ 33 , 34 ].…”