• Rodent Formulary: Anesthetic Drug Guidelines for Rodents (mg/kg of body weight)
• Rodent Formulary: Postoperative Analgesics for Rodents (mg/kg of body weight)
• Veterinary Guidelines on Use of Cryoanesthesia in Neonatal Rodents
• Use of Tribromoethanol (AVERTIN)

Rodent Formulary: Anesthetic Drug Guidelines for Rodents (mg/kg of body weight)

Drug	Category	Mice	Rats	Gerbils	Guinea Pigs	Hamsters
Atropine	Anticholinergic	0.04 IM or SQ	0.05 IM, IP	0.02 to 0.05 SQ, IM, IP	0.02 to 0.05 SQ, IM, IP	0.02 to 0.05 SQ, IM, IP
Ketamine + Xylazine	Dissociative Anesthetic	90-120 + 5-10 IM	40 to 90 + 15 IP	50 + 2 IP	50 + 5 IP	200 + 10 IP
Ketamine + Xylazine + Acepromazine	Dissociative Anesthetic	100 + 10 + 5 IP	22 to 44 + 2.5 + 0.75 IM	May precipitate seizures
Ketamine + Acepromazine	Dissociative Anesthetic	100 + 2.5 IM	30 to 75 + 2.5 to 3 IM		125 + 5 IM	150 + 5 IM
Thiopental	Barbiturate	25 to 50 IV	30 IV
Pentobarbital	Barbiturate	Neonate: 5 IP, 35 to 70 IV, 40 to 90 IP	30 to 40 IP	25 to 30 IP	25 to 30 IP	9 to 11.2 IP
Isoflurane	Inhalant Anesthetic	1 to 3% to effect	1-3% to effect	4% to effect	1.5	4% to effect

Source: Institutional Animal Care and Use Committee Handbook, 2008

 

Rodent Formulary: Postoperative Analgesics for Rodents (mg/kg of body weight)

Analgesic	Mice	Rats	Gerbils	Guinea Pigs	Hamsters
Buprenorphine	0.05 to 0.1 SQ 6 to 12 hours	0.2 to 0.5 SQ 8 to 12 hours	0.1 to 0.2 SQ 8 to 12 hours	0.05 SQ 6 to 12 hours	0.05 to 0.5 SQ 8 to 12 hours
Butorphanol	0.05 to 5 SQ q 4 hours	0.05 to 2 SQ q 4 hours
Meperidine	10 to 20 SQ/IP 2 to 4 hours	25 to 50 SQ 2 to 3 hours		10 to 20 SQ/IM 2 to 3 hours	20 SQ/IM 2 to 3 hours
Pentazocine	10 SQ 2 to 4 hours	10 SQ 2 to 4 hours

Source: Institutional Animal Care and Use Committee Handbook, 2008

 

Veterinary Guidelines on Use of Cryoanesthesia in Neonatal Rodents

Cryoanesthesia or hypothermia, produced by chilling the animal to near freezing temperature, may be used as a means of anesthetizing neonatal mice and rats pups less than six days of age. Their small size and body mass makes rapid cooling feasible through surface cooling. They are resistant to arrest of blood supply to the brain and tolerate extended periods of 1º C body temperature without known negative effects. Potential risks of hypothermia include ventricular fibrillation, tissue hypoxia and metabolic acidosis on warming.

When a need for hypothermia is demonstrated the following guideline should be followed:

• To induce hypothermia, pups may be placed in a latex glove and immersed up to the neck in crushed ice and water (2ºC to 3ºC) which requires a five to eight minute induction time (two to three minutes to unconsciousness and three to five minutes to complete blockage of neural transmission). Alternatively, pups may be placed in a paper-lined tube and packed in crushed ice which may require up to 15 minutes to obtain a surgical plane of anesthesia. Analgesia for hypothermia induced by these methods lasts approximately ten minutes.
• Do not place the animals directly on the cooling medium; provide a cloth, paper, or other barrier material. Simply placing conscious animals in a cold room or on an ice pack are unacceptable as induction may take 30 to 45 minutes.
• The anesthetic state may be prolonged by placing the hypothermic pup on an ice pack (3ºC to 4ºC). Studies have shown that rodent pups will maintain a core body temperature of approximately 5ºC when kept on an ice pack for a maximum of 15 minutes.
• Illumination of the surgical field should be fiber optic in nature, because incandescent bulbs may cause inadvertent and uncontrollable warming.
• After the procedure, avoid rapid rewarming because of possible tissue damage. Until animals are fully conscious they, cannot escape excessive heat generated by incandescent lamps, heating pads, or other warming devices. Pups can also be placed in an incubator at 33ºC for 20 to 30 minutes. Complete recovery typically requires 30 to 60 minutes.
• Supplemental oxygen may benefit the recovering animals.

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References

Phifer, CB and Terry, LM. 1986. Use of hypothermia for general anesthesia in preweanling rodents. Physiol. Behav. 38:887-890.

Danneman, PJ and Mandrell, TD. 1997. Evaluation of five agents/methods for anesthesia of neonatal rates. Lab. Anim. Sci. 47:386-395.