title: Epidural morphine reduces halothane MAC in the dog.
abstract: Morphine, 0.1 mg.kg-1 was administered epidurally on two different occasions to ten dogs to determine the effect of two different volumes of saline dilution, 0.13 and 0.26 ml.kg-1, on the minimum alveolar concentration (MAC) of halothane as determined by subcutaneous electrical current applied to the fore and hind limbs in a random order. Following MAC determination with halothane alone, epidural morphine was administered and MAC was redetermined. Epidural morphine significantly reduced, P less than 0.001, the MAC of halothane for fore and hind legs in both volume groups; from 1.04 +/- 0.038 to 0.68 +/- 0.034 and 0.60 +/- 0.017 for for and hind limbs, respectively, in the large volume group, and from 0.96 +/- 0.038 to 0.66 +/- 0.088 and 0.60 +/- 0.030 for fore and hind limbs, respectively, in the small volume group. The reduction in MAC was significantly greater, P less than 0.025, in the hind limb. This study indicates that epidural morphine reduces the halothane requirements in the dog in a segmental manner. The volume of administration was not shown to be critical. Epidural morphine, 0.1 mg.kg-1, diluted in 0.13 to 0.26 ml.kg-1 saline produces significant analgesia in the dog as far forward as the fore limb and will reduce the halothane requirement to permit surgery.
authors.affiliation: Department of Clinical Studies, Ontario Veterinary College, University of Guelph.
authors.forename: A
authors.initials: A
authors.lastname: Valverde
authors.forename: D H
authors.initials: DH
authors.lastname: Dyson
authors.forename: W N
authors.initials: WN
authors.lastname: McDonell
mesh_terms: D015360:Analgesia, Epidural; D000769:Anesthesia, Inhalation; D000818:Animals; D004285:Dogs; D005260:Female; D006221:Halothane / Q000008:administration & dosage*; D008297:Male; D009020:Morphine / Q000008:administration & dosage*
chemical_list: D009020:Morphine; D006221:Halothane