Analgesia and Anesthesia Information for Mice (Mus musculus)
Pain Recognition
Rodents in pain usually exhibit decreased exploratory behavior, piloerection, hunched posture, rough and ungroomed hair coat and ungroomed appearance. It must be emphasized that these signs are also associated with illness. Consult Veterinary Services for evaluation. Other clinical signs of pain may include:
- excessive scratching and licking
- more aggressive when handled
- vocalization when handled
- weight loss
- porphyrin tearing (rats)
- twitching of the back and flank (following laparotomy)
- mutilation of painful area
Physiologic parameters
| Body temperature | 37-38° C |
| Heart rate | 250-500/min | Respiratory rate | 35-135/min |
| Tidal volume | 0.6-1.4 ml |
The use of chloroform as an anesthetic agent is discouraged. Chloroform can cause renal tubular calcification and/or necrosis, particularly in male mice; the DBA/2 strain is the most susceptible.
Avertin is made by mixing equal amounts of tribromyl ethyl alcohol and tertiary amyl alcohol, then diluted to 2.5% in water or saline. Avertin has toxic degradation products, therefore, only a freshly mixed solution should be used. The 2.5% solution must be stored at 4¡C in the dark. The pH of the 2.5% solution must be above 5.
The therapeutic dose for carbon dioxide is close to the lethal dose. Carbon dioxide is very short acting. Carbon dioxide must be administered from a tank equipped with a regulatorÐdry ice is not acceptable.
Postoperative Analgesia For Rodents
Analgesia is required for rodents after surgery, unless there is scientific justification for withholding pain relief. Two procedures for providing analgesia to rodents are described below. The use of Marcaine is recommended for pain relief immediately after surgery. Long-lasting pain relief can be provided with buprenorphine.
Marcaine
Marcaine (bupivacaine) injected subcutaneously at the incision site(s) provides 8-10 hours of post surgical local anesthesia:
- Purchase 0.25% Marcaine (catalogue number #6310567 Marcaine vials 30 ml 0.25% 10/Bx $53.69/Bx Phone/Fax 800-772-4346/800-329-9109 http://www.henryschein.com)
- Dilute 1:10 in sterile water, saline or PBS and inject 0.1 ml/25 g mouse subcutaneously at the incision site.
Buprenorphine
Pain relief for more extended periods can be provided with buprenorphine (Buprenex). It should be noted that buprenorphine is a narcotic analgesic. All narcotic analgesics depress respiration to some extent and should not be administered to an animal that is already under anesthesia with an injectable agent which cannot be reversed. Depressive effects of anesthetics, analgesics, tranquilizers and sedatives are additive and should be taken into account when they are used together. If buprenorphine is used for anesthetic induction, the dose of anesthesia must be reduced by 10-25%. Alternatively, wait until the animal is completely recovered from anesthesia before administering. It is recommended that the appropriate dosage be established in advance for the strain of rodent you are anesthetizing.
- 0.05-0.1 mg/kg IM, SQ or IP administered at least once immediately after surgery for routine surgeries, and every 12 hours for up to 3 days if the procedure is expected to result in prolonged pain (e.g. orthopedic procedures).
- To prepare a dilution for smaller rodents, one 1 ml vial of Buprenex (0.3 mg) is drawn into a sterile syringe and added to 19 ml of sterile 5% dextrose in water or 0.9 % NaCl and dispensed into a sterile vial (e.g. a sterile serum tube). Label the tube "Buprenorphine HCl, 0.015 mg/ml" and the date prepared. Expiration date is either that from the original package, or 6 months from the date prepared. Protect from light.
- Administer 0.06-0.13 ml to an average 20 g mouse, 0.6-1.3 ml per average 200 g rat. There is a wide range of safety and efficacy for this drug. It is not necessary to weigh mice prior to administration and doses may be doubled if clinical efficacy is not apparent.
- Following an initial parenteral dose (see above), subsequent doses of buprenorphine may be given enterally at 0.5 mg/kg administered twice daily in Jello.
Buprenorphine Jello
| Species | Drug amount | Volume Water | Cube Volume Per Animal |
|---|---|---|---|
| Mouse | 1 ml vial (0.3 mg) | 15 ml | 1 ml |
| Rat | 1 ml vial (0.3 mg) | 3 ml | 4 ml |
Analgesia and Anesthesia Dosages
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