title: The effect of experimentally induced hypothyroidism on the isoflurane minimum alveolar concentration in dogs.
abstract: OBJECTIVE
  To determine the effect of experimentally induced hypothyroidism on isoflurane (ISO) minimum alveolar concentration (MAC) in dogs.
  
  
  METHODS
  Prospective experimental study.
  
  
  METHODS
  Eighteen adult female mongrel dogs, age 2-4 years and weighing 8.2-13.1 kg.
  
  
  METHODS
  Hypothyroidism was induced in nine dogs by the intravenous administration of 1 mCi kg(-1) of (131) Iodine. The remaining nine dogs served as controls. Dogs were studied 9-12 months after the induction of hypothyroidism. Anesthesia was induced with ISO in oxygen via a mask. The trachea was intubated, and anesthesia was maintained using ISO in oxygen using a semi-closed rebreathing circle system. The dogs were mechanically ventilated to maintain an end-tidal carbon dioxide concentration between 35 and 45 mmHg. End-tidal ISO concentrations were measured with an infrared gas analyzer. The MAC was determined in duplicate using a tail clamp technique. The mean values for the groups were compared using a two sample t-test.
  
  
  RESULTS
  The mean ± SD MAC of isoflurane in the hypothyroid and euthyroid dogs was 0.98 ± 0.31% and 1.11 ± 0.26%, respectively. The mean MAC of isoflurane in hypothyroid dogs was not significantly different from the mean MAC of isoflurane in the control dogs (p = 0.3553).
  
  
  CONCLUSIONS
  The MAC of ISO in dogs was not significantly affected by experimentally induced hypothyroidism. The dose of ISO in dogs with hypothyroidism does not need to be altered.
authors.affiliation: Department of Small Animal Clinical Sciences, Virginia Maryland Regional College of Veterinary Medicine, Blacksburg, VA, USA.
authors.forename: Stephanie H
authors.initials: SH
authors.lastname: Berry
authors.forename: David L
authors.initials: DL
authors.lastname: Panciera
mesh_terms: D000769:Anesthesia, Inhalation / Q000662:veterinary; D018685:Anesthetics, Inhalation / Q000008:administration & dosage / Q000493:pharmacokinetics*; D000818:Animals; D004283:Dog Diseases / Q000139:chemically induced* / Q000378:metabolism; D004285:Dogs; D005260:Female; D007037:Hypothyroidism / Q000139:chemically induced / Q000662:veterinary*; D007455:Iodine / Q000633:toxicity*; D007457:Iodine Radioisotopes; D007530:Isoflurane / Q000008:administration & dosage / Q000737:chemistry / Q000493:pharmacokinetics*; D011650:Pulmonary Alveoli / Q000737:chemistry*
chemical_list: D018685:Anesthetics, Inhalation; D007457:Iodine Radioisotopes; D007455:Iodine; D007530:Isoflurane
keywords: dogs; hypothyroidism; isoflurane; minimum alveolar concentration