Post-anesthetic hyperthermia in cats.

Abstract

OBJECTIVE: To assess whether administration of hydromorphone and, or ketamine are associated with post-anesthetic hyperthermia in cats undergoing routine surgery. STUDY DESIGN: Prospective clinical study. ANIMALS: Forty healthy, adult cats undergoing ovariohysterectomy (OVH), castration, or declaw surgery. MATERIALS AND METHODS: Each cat was assigned randomly to one of four groups (n = 10). For pre-anesthetic medication, all cats received subcutaneous (SC) glycopyrrolate (0.01 mg kg(-1)) and acepromazine (0.02 mg kg(-1)) and either hydromorphone (0.1 mg kg(-1) SC) or medetomidine (7.5 microg kg(-1) SC). Anesthesia was induced with either diazepam (0.1 mg kg(-1)) and ketamine (5 mg kg(-1)) or propofol (6 mg kg(-1) injected to effect). Group 1 (HDK) received hydromorphone and diazepam-ketamine. Group 2 (HP) received hydromorphone and propofol. Group 3 (MDK) received medetomidine and diazepam-ketamine. Group 4 (MP) received medetomidine and propofol. Rectal temperature was measured before drugs were given, at tracheal extubation and at hourly intervals for 5 hours thereafter. RESULTS: During the 5 hours after anesthesia and surgery, at least one cat in every group had a rectal temperature >39.2 degrees C (102.5 degrees F). The percentage of observations for which a cat's temperature exceeded its pre-anesthetic temperature in groups HDK, HP, MDK, and MP were 86%, 80%, 25%, and 34%, respectively. Maximum temperatures in groups HDK, HP, MDK, and MP were 41.6 degrees C (107.0 degrees F), 40.3 degrees C (104.2 degrees F), 39.2 degrees C (102.6 degrees F), and 40.1 degrees C (104.1 degrees F), respectively. By 5 hours after tracheal extubation there were no differences in temperature between the treatment groups. CONCLUSION: For up to 5 hours following anesthesia and surgery, cats might have body temperatures that exceed their pre-anesthesia body temperatures. The use of hydromorphone is associated with post-anesthetic hyperthermia. However, hyperthermia may occur when other drugs are used. CLINICAL RELEVANCE: Cats given hydromorphone should be closely monitored for hyperthermia following anesthesia and surgery.