title: Effects of intramuscular administration of low doses of medetomidine and medetomidine-butorphanol in middle-aged and old dogs.
abstract: OBJECTIVE
  To determine effects of low doses of medetomidine administered with and without butorphanol and glycopyrrolate to middle-aged and old dogs.
  
  
  METHODS
  Prospective randomized clinical trial.
  
  
  METHODS
  88 healthy dogs > or = 5 years old.
  
  
  METHODS
  Dogs were assigned randomly to receive medetomidine (2, 5, or 10 micrograms/kg [0.9, 2.3, or 4.6 micrograms/lb] of body weight, i.m.) alone or with glycopyrrolate (0.01 mg/kg [0.005 mg/lb], s.c.), medetomidine (10 micrograms/kg) and butorphanol (0.2 mg/kg [0.1 mg/lb], i.m.), or medetomidine (10 micrograms/kg), butorphanol (0.2 mg/kg), and glycopyrrolate (0.01 mg/kg). Anesthesia was induced with thiopental sodium and maintained with isoflurane. Degree of sedation and analgesia were determined before and after medetomidine administration. Respiratory rate, heart rate, and mean arterial blood pressure were determined 10 and 30 minutes after medetomidine administration. Adverse effects and amounts of thiopental and isoflurane used were recorded.
  
  
  RESULTS
  Sedation increased after medetomidine administration in 79 of 88 dogs, but decreased in 7 dogs that received 2 or 5 micrograms of medetomidine/kg. Mean postsedation analgesia score and amounts of thiopental and isoflurane used were less in dogs that received medetomidine and butorphanol, compared with other groups. Respiratory rate, heart rate, and blood pressure were not different among groups. Significantly more adverse effects developed in dogs that did not receive glycopyrrolate.
  
  
  CONCLUSIONS
  Administration of medetomidine (10 micrograms/kg, i.m.) and butorphanol (0.2 mg/kg, i.m.) induced sedation and analgesia and reduced amounts of thiopental and isoflurane required for anesthesia in middle-aged and old dogs. Glycopyrrolate decreased frequency of medetomidine-associated adverse effects.
authors.affiliation: Department of Veterinary Clinical Sciences, College of Veterinary Medicine, Ohio State University, Columbus 43210, USA.
authors.forename: W W
authors.initials: WW
authors.lastname: Muir
authors.forename: J L
authors.initials: JL
authors.lastname: Ford
authors.forename: G E
authors.initials: GE
authors.lastname: Karpa
authors.forename: E E
authors.initials: EE
authors.lastname: Harrison
authors.forename: J E
authors.initials: JE
authors.lastname: Gadawski
mesh_terms: D000759:Adjuvants, Anesthesia / Q000008:administration & dosage / Q000494:pharmacology; D000375:Aging / Q000187:drug effects / Q000502:physiology; D018712:Analgesics, Non-Narcotic / Q000008:administration & dosage* / Q000494:pharmacology; D000701:Analgesics, Opioid / Q000008:administration & dosage* / Q000494:pharmacology; D019162:Anesthetics, Combined / Q000008:administration & dosage; D018685:Anesthetics, Inhalation / Q000008:administration & dosage; D018686:Anesthetics, Intravenous / Q000008:administration & dosage; D000818:Animals; D001794:Blood Pressure / Q000187:drug effects; D002077:Butorphanol / Q000008:administration & dosage* / Q000494:pharmacology; D004285:Dogs / Q000502:physiology*; D005260:Female; D006024:Glycopyrrolate / Q000008:administration & dosage / Q000494:pharmacology; D006339:Heart Rate / Q000187:drug effects; D006993:Hypnotics and Sedatives / Q000008:administration & dosage* / Q000494:pharmacology; D007273:Injections, Intramuscular / Q000662:veterinary; D007530:Isoflurane / Q000008:administration & dosage; D008297:Male; D020926:Medetomidine / Q000008:administration & dosage* / Q000494:pharmacology; D011229:Preanesthetic Medication / Q000662:veterinary*; D012119:Respiration / Q000187:drug effects; D013874:Thiopental / Q000008:administration & dosage
chemical_list: D000759:Adjuvants, Anesthesia; D018712:Analgesics, Non-Narcotic; D000701:Analgesics, Opioid; D019162:Anesthetics, Combined; D018685:Anesthetics, Inhalation; D018686:Anesthetics, Intravenous; D006993:Hypnotics and Sedatives; D007530:Isoflurane; D013874:Thiopental; D020926:Medetomidine; D002077:Butorphanol; D006024:Glycopyrrolate