OAR Informational Sheet: Local Analgesia/Anesthesia for Rodents

Informational Sheet: The IACUC has provided a set of guidance documents (Policies, Guidelines, and Informational Sheets) for use when planning animal procedures at the University of Iowa. Informational Sheets provide information about frequently asked questions and represents guidance for best practices. Deviation from the recommendation(s) does not require specific justification.

Purpose: 

The purpose of this document is to educate researchers on effective uses of local analgesics and anesthetics in rodents.  When used properly local analgesics and anesthetics can reduce pain and distress in laboratory animals.

Local Anesthesia Along Intended Incisions (Line Blocks)

Materials:

  • Lidocaine HCl (without epinephrine) 2% (20 mg/ml) and/or
  • Marcaine HCl (Bupivacaine) 0.5% (5 mg/ml)
  • Hypodermic needles (25 or 27g, 1/2” or smaller)
  • 1 cc syringes
  • Sterile multi-use injection vials for dilutions
  • Sterile, pyrogen-free water for injection

Formulary: Rats and Mice

Local Anesthetic Dose* Application Notes
Lidocaine (2%) Dilute to 0.5%, do not exceed 7mg/kg total dose; Incisional line block Use Locally before making surgical incision Faster onset than bupivicaine but short (<1hour) duration of action
Bupivicaine (0.5%) Dilute to .25%, do not exceed 8mg/kg total dose; incisional line block Use locally before making surgical incision Slower onset than lidocaine but longer (~4-8 hour) duration of action
0.5% Lidocaine/0.25% Bupivacaine mixture See formulation below; do not exceed maximum dose Inject locally before surgical incision Best option - rapid action of lidocaine with prolonged action of bupivacaine

Dilutions:

  • Lidocaine
    Dilute the 2% (20 mg/ml) Lidocaine 1:4 to get final concentration of 0.5%
    • Example:  0.5 mL of 2% lidocaine + 1.5 mL sterile saline
    • Label with drug, concentration, and expiration date
    • See "IACUC Guidelines: Use of Drugs and Chemicals in Laboratory Animals" for further details (proper handling, expiration guidance, etc.)
  • Bupivacaine
    Dilute the 0.5% (5 mg/ml) Bupivacaine 1:2 to get final concentration of 0.25%
    • Example: 0.5 mL of 0.5% bupivacaine + 0.5 mL sterile saline
    • Label with drug, concentration, and expiration date
    • See “IACUC Guidelines: Use of Drugs and Chemicals in Laboratory Animals” for further details (proper handling, expiration guidance, etc.)
  • 50/50 Mixutre of Lidocaine/Bupivacaine
    Dilute  2% (20 mg/ml) Lidocaine 1:4 and 0.5% (5mg/mL) Bupivacaine 1:2 in the same vial
    • Example: 0.5 mL 2% lidocaine + 1 mL 0.5% bupivacaine + 0.5 mL sterile saline
    • Label with drug, concentration, and expiration date
    • See “IACUC Guidelines: Use of Drugs and Chemicals in Laboratory Animals” for further details (proper handling, expiration guidance, etc.)

Maximum volumes

Weight of Mouse

Maximum Volume Diluted Lidocaine (0.5%) Do not exceed:

Maximum Volume Diluted Bupivicaine (0.25%) Do not exceed:
25g 0.03ml 0.08ml
35g 0.05ml 0.11ml
45g 0.06ml 0.14ml
55g 0.07ml 0.17ml
Weight of Rat Maximum Volume Diluted Lidocaine (0.5%) Do not exceed: Maximum Volume Diluted Bupivicaine (0.25%) Do not exceed:
250g 0.35ml 0.8ml
350g 0.49ml 1.12ml
250g 0.63ml 1.44ml
550g 0.77ml 1.76ml

Line Block Procedure

1. Determine maximum dose that can be used depending on weight of animal
2. Anesthetize the animal, and prepare skin for aseptic surgery
3. Inject local anesthetic into the subcutaneous space (“line block”) below the planned incision line, while withdrawing the needle along incision line

Local Anesthetics should be used pre-operatively (before the first incision) and can be used in conjunction with opioid analgesics and/or NSAIDs for controlling moderate to severe pain. Intramuscular and intravenous injection of local anesthetics must be avoided. Systemic toxicity (seizures, heart rhythm disturbances and death) results from overdosage or accidental intravenous injection.

 

References

"Local Analgesia/Anesthesia for Rodents." Animalcare.ubc.ca. N.p., n.d. Web. 16 Nov. 2012.

Last Reviewed by Committee 4/11/18