VA
Pittsburgh Healthcare System IACUC
Guidelines
Recommended for Anesthetics and Analgesics for use in Rodents
The following drugs and combinations of drugs are recommended by
the Pittsburgh VAMC Subcommittee on Animal Research (SAR). All drugs proposed
for use in animals must be described in the ACORP and approved by the SAR. Drugs
of these categories and combinations of them not listed in this document can be
used when approved by the SAR.
Anesthetics
Inhalants
Inhalants are preferred because of the ease of controlling depth
of anesthesia and the brevity of recovery. However, the animal’s vital signs
must be monitored to avoid an overdose or light anesthesia. Reliable vaporizers
must be used for the effective delivery of volatile anesthesics; oxygen or a
mixture of oxygen and nitrous oxide is the carrier gas of choice, but
combination of oxygen and nitrous oxide can be used at 30%170%
or 50%/50% respectively. Humans must not be exposed to the
vapors of inhalant anesthetics.
1. Isoflurane: Induction is best done in a chamber using 4% isoflurane. Most rodents can usually be maintained in surgical anesthesia using 1 to 3% isoflurane, but it is used at +1- to effect.
2. Halothane: Induction is best done on a chamber using 4% halothane. Most rodents can usually be maintained in surgical anesthesia using 1 to 2% halothane, but it is used at +1- to effect. Unlike isoflurane, a percentage of halothane is metabolized by the liver resulting in marked microsomal enzyme induction.
Injectables
Injectable anesthetics are more difficult to titrate than
inhalants and usually have a longer recovery period. However, they have the
advantage of ease of administration and the lack of concern of human exposure.
1. Ketamine: By itself, ketamine should be used for restraint and for minor procedures as it usually does not produce deep anesthesia and causes muscular rigidity. However, in the following combinations, it can be used for major surgical procedures in rodents:
A. Ketamine and Xylazine (respectively)
Rat: 40-80mg/kg IM and 5-10 mg/kg IM
Mouse: 80-120mg/kg IM and 5-10 mg/kg IM
B. Ketamine, Xylazine, and Acepromazine (respectively)
Mouse: 30 mg/kg IM, 6 mg/kg IM, and 1mg/kg IM
2. Sodium Pentobarbital: The former “gold standard” of veterinary anesthesia, pentobarbital, can still be used but the lack of good analgesia is a drawback.
Rat: 40-50 mg/kg IP to effect
Mouse:
40-70 mg/kg IP to effect. Recommend giving ketoprofen 5 mg/kg SC
for supplemental analgesia; other analgesics can be used, but
some cause additional respiratory and cardiac depression.
3. Avertin: No longer available commercially but can be formulated as follows: 2.5 gm. 2,2,2-tribromoethanol in 5.0 ml of 2-methyl-2-butanol (tertiary amyl alcohol) and raise temperature to 50 degrees C; add this mixture to 200 ml of sterile distilled water and stir to dissolve. This gives a 1.25% solution. Avertin must be protected from light and stored at 4 degrees C; discarded if the pH falls below 5.0 as it becomes toxic.
Mouse: 0.2m1 of the above solution/10 gram BW, IP
4. Chloral Hydrate: Must be used at a concentration of 5% or less. Some individuals object to the use of chloral hydrate as an anesthetic, but there is ample literature supporting its use at high doses.
Rat: 400 mg/kg, IP
Analgesics
It has been shown that animals, including humans, recover faster
from surgery when post-surgical analgesics are used. Analgesics are most
effective if they are administered and in effect before the pain starts.
Analgesics should be used post-surgically, except for very minor procedures, and
when other painful situations are expected unless there is a scientific reason
for not using them.
1. Ketoprofen:
Rat: 5.0 mg/kg, SC. Q 12 hrs
Mouse:
5.0 mg/kg, SC, Q 12 hrs
2. Buprenorphine:
Rat: 0.01 to 0.05 mg/kg, SC, Q 8-12 hrs
Mouse:
0.05 to 0.1 mg/kg, SC or IV, Q 12
hrs
3. Butorphenol:
Rat: 2.0 mg/kg, SC, Q 4 hrs.
Mouse: 1 to 5 mg/kg,
SC, Q 4 hrs
4. Morphine:
Rat: 2.5 mg/kg, SC, Q 2-4 hrs.
Mouse: 2.5 mg/kg, SC, Q 2-4 hrs
(Approved May, 2002)