Anesthesia and Analgesia Guidelines

Note: These guidelines are intended to serve as a general reference only. When planning any procedure involving anesthesia and/or surgery, please consult one of the laboratory animal veterinarians in the Office of Laboratory Animal Care (OLAC). He/she can provide guidance and detailed information in selecting the most appropriate anesthetic and analgesic protocol for your species and procedure.

Contents: Anesthetics (general comments) • Mammals • Birds and Reptiles • Amphibians and Fish • Analgesics • References

ANESTHETICS

Isoflurane delivered through a precision vaporizer is the anesthetic agent of choice for virtually all species. It provides rapid induction and recovery and is minimally metabolized by the body (<0.2% drug residue or breakdown products excreted by liver or kidneys). Isoflurane vaporizers are available to investigators in all UT facilities. Laboratory animal veterinarians, managers, and technicians are available to provide instruction and assist in operation.

Methoxyflurane and halothane are also available for investigator use.

Note: All inhalant anesthetic systems should have proper waste gas scavenging systems.

Isoflurane and Halothane
           induction concentrations  3-4%
           maintenance concentrations  0.5-2%

Methoxyflurane
           open drop chamber and/or nose cone

If inhalant anesthetics are unavailable, the following agents represent a partial list of injectable anesthetics that may be used for minor procedures. Some of these may also be used in combination with isoflurane. Please consult the lab animal veterinarians to determine which anesthetic combination is optimal for your research needs:

MAMMALS

Anticholinergics

Atropine

dogs, cats, ferrets: 0.02-0.04 mg/kg IM, SC
pigs: 0.05 mg/kg IM
primates: 0.02-0.05 mg/kg IM
rabbits: 0.5 mg/kg IM, SC
ruminants: 0.13 mg/kg IM, SC

Tranquilizers/Sedatives

Acepromazine

dogs, cats: 0.05-0.1 mg/kg IM, SC (3 mg max.)
ferrets: 0.2-0.5 mg/kg IM,SC
horses: 0.02-0.05 mg/kg IM, IV
pigs: 0.11-1.1 mg/kg IM, IV, SC
rabbits: 1.0 mg/kg IM
ruminants: 0.05-0.2 mg/kg IM, SC

Midazolam

dogs, cats, ferrets: 0.2-0.4 mg/kg IM, or IV
pigs: 0.1-0.5 mg/kg IM, IV
rabbits: 2.0 mg/kg IV, IP
ruminants: 0.4-1.3 mg/kg IV

Xylazine

horses*: 0.2-1.0 mg/kg IV.
pigs: 0.2-2.0 mg/kg IM
ruminants: .05-0.3 mg/kg IM, SC

1. * High dose causes profound sedation.
2. * IM use, need to double IV dose.
3. * Duration of action is short.

Dissociatives

Ketamine

cats: 10-20 mg/kg IM
primates: 5-20 mg/kg IM

Induction Agents

Thiopental

dogs, cats: 8-12 mg/kg IV
mice: 20-50 mg/kg IV
pigs: 6.6-25.0 mg/kg IV
rats: 20-40 mg/kg IV
rabbits: 15-30 mg/kg IV
ruminants: 25 mg/kg IV

Anesthetic Combinations

Ketamine/Xylazine

ferrets: 20-30 mg/kg Ketamine IM and 1-4 mg/kg Xyl IM
guinea pigs: (anesthesia inconsistent) 40-100 mg/kg Ketamine IP, IM and 4-5 mg/kg Xylazine IP
hamsters: 80-100 mg/kg Ketamine IP and 7-10 mg/kg Xylazine IP
mice: (anesthesia inconsistent) 100 mg/kg Ketamine IP and 5 mg/kg Xylazine IP
pigs: 20 mg/kg Ketamine IM and 2.0 mg/kg Xylazine IM
primates: 10 mg/kg Ketamine IM and 0.25-2.0 mg/kg Xylazine IM
rabbits: 35-50 mg/kg Ketamine IM and 5 - 10 mg/kg Xylazine IM
rats: 87 mg/kg Ketamine IP and 13 mg/kg Xylazine IP
ruminants: 5-15 mg/kg Ketamine IM, SC and 0.1-0.2 mg/kg Xylazine IM, SC

Ketamine/Midazolam

dogs, cats: 10 mg/kg Ketamine IV and 0.5 mg/kg Midazolam IV

Tiletamine/Zolazepam (Telazol)

dogs: 6-12 mg/kg IM or SC

Tiletamine/Zolazepam (Telazol)/Xylazine

pigs: 4.4 mg/kg Telazol IM and 2.2 mg/kg Xylazine IM

Tribromoethanol

mice: 125-250 mg/kg IP

BIRDS AND REPTILES

Isoflurane is the most appropriate agent for anesthetizing birds and reptiles. Birds can be induced in a chamber or with a face mask, and reptiles can be directly intubated (turtles must first be sedated with 20-40 mg/kg IM Ketamine). Injectables do not consistently provide adequate anesthesia, have a narrow margin of safety, and in reptiles, have a very prolonged recovery (days).

AMPHIBIANS AND FISH

Tricaine methane sulfonate is the agent of choice for these species. General immersion doses are:

fish: 50-300 mg/L
frogs/salamanders: 0.5-2 g/L (500-2000 mg/L)
tadpoles/newts: 200-500 mg/L
toads: 1000-3000 mg/L

ANALGESICS

Analgesics should always be given with the premedications or as anesthesia is induced, to provide maximum benefit. Supplemental doses should be administered at least twice postoperatively, and then as necessary (please consult lab animal veterinarians when determining analgesic needs).

Preferred analgesics are:

Butorphanol (usually provides 4 - 6 hour pain relief)

birds: 0.2-2.0 mg/kg IM (empirical)
cats: 0.4 mg/kg SC
dogs: 0.2-0.4 mg/kg SC, IM, IV
horses: 0.02-0.05 mg/kg IV, IM q4-6 hrs.

Comments: (1) Might cause mild agitation in some horses. (2) Short duration of action. (3) Might consider using with a low dose of acepromazine.

Butorphanol (continued)

mice: 1.0-5.0 mg/kg SC
pigs: 0.1-0.3 mg/kg IM
rabbits: 0.1-0.5 mg/kg SC
rats: 2.0 mg/kg SC (can go much higher if necessary)
reptiles: 0.2 mg/kg IM (empirical)

Buprenorphine (usually 8 - 10 hour pain relief)

birds: 0.01-0.05 mg/kg IM (empirical)
cats: 0.005-0.01 mg/kg SC, IM
dogs: 0.01-0.02 mg/kg SC
guinea pigs: 0.5-0.8 mg/kg SC
mice: 2.5 mg/kg SC, IP
pigs: 0.05-0.1 mg/kg IM
primates: 0.01 mg/kg IM, IV
rabbits: 0.02-0.05 mg/kg IM, SC, IV
rats: 0.25-1.6 mg/kg IP
reptiles: 0.005-0.02 mg/kg IM every 24-48 hr (empirical)

Phenylbutazone

horses: 2-4 mg/kg IV or orally, q12 hr.

Comments: (1) Use high dose initially. (2) Due to toxic effects, the dose must be reduced to the low end of the dosing range from the second day onward.

Flunixin meglumine

horses: 0.5-1.1 mg/kg IV, IM, oral q8-12 hr.

Comments: Use high dose for first 24 hrs postsurgery. Dose can be reduced from second day onward, based on clinical status and severity of pain. As for phenylbutazone, potential for toxicity exists.

Other available analgesics include aspirin, carprofen, xylazine, meperidine and others. Please consult laboratory animal veterinarians when choosing analgesic drugs and doses.

KEY REFERENCES

1. Anesthesia and Analgesia in Laboratory Animals; Kohn, Wixson, White, Benson (eds); Academic Press, 1997.
2. Laboratory Animal Anesthesia, Flecknell; Academic Press, 1987.
3. Manual of Small Animal Anesthesia; Paddleford; Churchill Livingstone, 1988.
4. Large Animal Anesthesia, 2nd edition; Reibold, Geiser, Goble (eds).
5. Veterinary Anesthesia, Lumb Jones, 3rd edition; Thurmon, Tranquilli, Benson (eds).
6. Veterinary Anesthesia; Short (ed).