Effects of opioids and anesthetic drugs on body temperature in cats.
OBJECTIVE
To determine which class of opioid alone or in conjunction with other anesthetic drugs causes post-anesthetic hyperthermia in cats.


METHODS
Prospective, randomized, crossover study.


METHODS
Eight adult, healthy, cats (four spayed females and four castrated males weighing 3.8 +/- 0.6 kg).


METHODS
Each cat was instrumented with a wireless thermistor in the abdominal cavity. Temperature in all phases was recorded every 5 minutes for 5 hours. Population body temperature (PBT) was recorded for approximately 8 days. Baseline body temperature is the final 24 hours of the PBT. All injectable drugs were given intramuscularly. The cats were administered drugs in four phases: 1) hydromorphone (H) 0.05, 0.1, or 0.2 mg kg(-1); 2) morphine (M) (0.5 mg kg(-1)), buprenorphine (BUP) (0.02 mg kg(-1)), or butorphanol (BUT) (0.2 mg kg(-1)); 3) ketamine (K) (5 mg kg(-1)) or ketamine (5 mg kg(-1)) plus hydromorphone (0.1 mg kg(-1)) (KH); 4) isoflurane in oxygen for 1 hour. Fifteen minutes prior to inhalant anesthetic, cats received either no premed (I), hydromorphone (0.1 mg kg(-1)) (IH), or hydromorphone (0.1 mg kg(-1)) plus ketamine (5 mg kg(-1)) (IHK).


RESULTS
Mean PBT for all unmedicated cats was 38.9 +/- 0.6 degrees C (102.0 +/- 1 degrees F). The temperature of cats administered all doses of hydromorphone increased from baseline (p < 0.03) All four opioids (H, M, BUP and BUT) studied increased body temperature compared with baseline (p < 0.005). A significant difference was observed between baseline temperature values and those in treatment KH (p < 0.03). Following recovery from anesthesia, temperature in treatments IH and IHK was different from baseline (p < 0.002).


CONCLUSIONS
All of the opioids tested, alone or in combination with ketamine or isoflurane, caused an increase in body temperature. The increase seen was mild to moderate (<40.1 degrees C (104.2 degrees F) and self limiting.
Posner
Lysa P
LP
Department of Molecular and Biomedical Sciences, North Carolina State College of Veterinary Medicine, 4700 Hillsborough St., Raleigh, NC 27606, USA. lysa_posner@ncsu.edu
Pavuk
Alana A
AA
Rokshar
Jennifer L
JL
Carter
Jennifer E
JE
Levine
Jay F
JF
D000701:Analgesics, Opioid / Q000494:pharmacology*; D000777:Anesthetics / Q000494:pharmacology*; D019162:Anesthetics, Combined / Q000494:pharmacology; D018685:Anesthetics, Inhalation / Q000494:pharmacology; D000818:Animals; D001831:Body Temperature / Q000187:drug effects*; D002047:Buprenorphine / Q000494:pharmacology; D002415:Cats / Q000502:physiology*; D018592:Cross-Over Studies; D005260:Female; D004091:Hydromorphone / Q000494:pharmacology; D007530:Isoflurane / Q000494:pharmacology; D007649:Ketamine / Q000494:pharmacology; D008297:Male; D008305:Malignant Hyperthermia / Q000662:veterinary; D009020:Morphine / Q000494:pharmacology
D000701:Analgesics, Opioid; D000777:Anesthetics; D019162:Anesthetics, Combined; D018685:Anesthetics, Inhalation; D002047:Buprenorphine; D007649:Ketamine; D009020:Morphine; D007530:Isoflurane; D004091:Hydromorphone