Effects of butorphanol and carprofen on the minimal alveolar concentration of isoflurane in dogs

Abstract

Results suggest that administration of butorphanol alone or in combination with carprofen significantly reduces the MAC of isoflurane in dogs; however, the effects of butorphanol and carprofen are additive, not synergistic.

Effects of Carprofen and Meloxicam with or without Butorphanol on the Minimum Alveolar Concentration of Sevoflurane in Dogs

“…In the present study, however, the administration of carprofen or meloxicam in combination with butorphanol provided only additive sevoflurane-sparing effects in dogs. Similar results have been observed in dogs after administration of butorphanol in combination with carprofen [16] and rabbits after administration of butorphanol in combination with meloxicam [30]. There is conflicting information in the literature regarding the effect of butorphanol on the MAC of inhalant anesthetics in dogs [16,25,27].…”

“…Alibhai and Clarke [1] reported that carprofen minimally influenced the MAC of halothane in dogs. On the other hand, Ko et al [16] reported that preoperative oral administration of carprofen alone produced 6.24 ± 3.42% of the percentage MAC reduction, but the isoflurane-MAC values were not significantly different from control (0.90 ± 0.21% vs 1.03 ± 0.22%, P=0.069). In the present study, the preoperative subcutaneous administration of carprofen or meloxicam alone produced 11.3 ± 8.3% or 12.9 ± 10.2% reduction of the percentage MAC, respectively, that were significantly different compared to control.…”

“…Purposeful movement was defined as substantial movement of the head or extremities and did not include coughing, chewing, swallowing, or an increased respiratory effort. The clamp circumscribed the tail and did not puncture the skin of the dog thereby producing a blunt force on the tail [16].…”

“…MAC determination: The MAC of sevoflurane was determined by use of the tail clamp method [10,16], with minor modifications. Briefly, dogs were allowed to equilibrate for 30 min at ETSEV 2.4%.…”

“…Butorphanol is an opioid agonist-antagonist frequently administered either intramuscularly or intravenously as preanesthetic medication to manage pain in dogs [12,33,[35][36][37]. The co-administration of oral carprofen and intravenous butorphanol produces additive decreases in the minimum alveolar concentration (MAC) of isoflurane in dogs [16]. Potential benefits of decreasing the amount of inhalant anesthetic required to maintain anesthesia include decrease in doserelated cardiorespiratory depression, inhalant anesthetic pollution, and cost of anesthesia.…”