Mice Anesthetization Protocols

Anesthetizing mice is a common practice in biomedical research for various purposes, including surgery, imaging studies, or the collection of tissues. Several methods are available, including injectable and inhalant anesthetics.

1. Injectable Anesthetics: Some commonly used injectable anesthetics are ketamine, xylazine, and acepromazine.

   – The combination of Ketamine (an analgesic) and Xylazine (a sedative) is commonly used for anesthesia in rodents.

   – This mixture provides both anesthesia and analgesia, and the effects can last from 30 to 120 minutes, depending on the route of administration, the dose, and the specific animal.

   – The typical dose is 60–100 mg/kg ketamine and 5–10 mg/kg xylazine by intraperitoneal (IP) injection.

Usage Example:

Mice were anesthetized via intraperitoneal injection of ketamine (100 mg per kg body weight) and xylazine (10 mg per kg body weight). (Yin et al., 2023, Nat. Immunol.)

2. Inhalant Anesthetics: Isoflurane is a commonly used inhalant anesthetic. Other options include Sevoflurane and Enflurane.

   – Isoflurane is frequently the anesthetic of choice for minor surgeries due to its rapid induction and recovery times.

   – It’s administered through a precision vaporizer. The general concentration for induction ranges from 2–5%, and for maintenance, 1–3%.

   – Mice are generally placed in an induction chamber, and then the anesthesia is delivered through the nose.

3. Medetomidine-Midazolam-Fentanyl (MMF) Combination: In some instances, another combination that might be used is MMF.

   – This combination is typically administered via the subcutaneous route.

   – It provides excellent anesthesia and analgesia and lasts approximately 25–40 minutes, depending on the rodent and the dose.

Regardless of the method, all anesthetization techniques should be carefully monitored, ensuring the depth of anesthesia is sufficient but not excessive. Respiration rate, heart rate, and reflex activity can provide useful information about anesthesia depth. In the case of prolonged procedures, heat support should be supplied, as small animals such as mice can quickly become hypothermic.

After the procedure, mice must be monitored until they fully recover.

It’s crucial to remember that your institution’s animal care and use committee must approve every procedure involving anesthesia and mice.

All protocols should prioritize the animal’s well-being, particularly minimizing distress and pain. Please adhere to the “three-R” framework for the ethical use of animals in scientific research: Replacement, Reduction, and Refinement.

Please consult with a veterinarian or a professional technician to administer these procedures.