title: Clinical evaluation of intranasal medetomidine-ketamine and medetomidine-S(+)-ketamine for induction of anaesthesia in rabbits in two centres with two different administration techniques.
abstract: OBJECTIVE
  The aim was to compare efficacy and side effects of induction with medetomidine-ketamine or medetomidine-S(+)-ketamine by intranasal (IN) instillation in rabbits and to evaluate both protocols during subsequent isoflurane anaesthesia.
  
  
  METHODS
  Prospective, blinded, randomized experimental study in two centres.
  
  
  METHODS
  Eighty-three healthy New Zealand White rabbits undergoing tibial or ulnar osteotomy.
  
  
  METHODS
  Medetomidine (0.2 mg kg-1) with 10 mg kg-1ketamine (MK) or 5 mg kg-1S(+)-ketamine (MS) was administered IN to each rabbit in a randomized fashion. In Centre 1 (n = 42) rabbits were held in sternal recumbency, and in Centre 2 (n = 41) in dorsal recumbency, during drug instillation. Adverse reactions were recorded. If a rabbit swallowed during endotracheal intubation, half of the initial IN dose was repeated and intubation was re-attempted after 5 minutes. Anaesthesia was maintained with isoflurane. Heart rate, blood pressure, endtidal carbon dioxide concentration and blood gases were recorded. Data were analysed using Student's t-test, Mann-Whitney test and Fisher's exact test.
  
  
  RESULTS
  In all, 39 animals were assigned to the MK group and 44 to the MS group. Two rabbits in the MS group held in dorsal recumbency died after instillation of the drug. Eight (MK) and 11 rabbits (MS) were insufficiently anaesthetized and received a second IN dose. One rabbit in MK and three in MS required an isoflurane mask induction after the second IN dose. There were no significant differences between treatments for induction, intraoperative data, blood gas values and recovery data.
  
  
  CONCLUSIONS
  This study indicated that medetomidine-ketamine and medetomidine-S(+)-ketamine were effective shortly after IN delivery, but in dorsal recumbency IN administration of S(+)-ketamine led to two fatalities. Nasal haemorrhage was noted in both cases; however, the factors leading to death have not been fully elucidated.
authors.affiliation: VAS, Veterinary Anaesthesia Services-International, Winterthur, Switzerland.
authors.forename: Linda C
authors.initials: LC
authors.lastname: Weiland
authors.affiliation: Preclinical Surgery, AO Research Institute, Davos Platz, Switzerland.
authors.forename: Katharina
authors.initials: K
authors.lastname: Kluge
authors.affiliation: Section of Anaesthesiology, Equine Department, Vetsuisse Faculty University of Zurich, Zurich, Switzerland.
authors.forename: Annette P N
authors.initials: APN
authors.lastname: Kutter
authors.affiliation: VAS, Veterinary Anaesthesia Services-International, Winterthur, Switzerland; Centre for Applied Biotechnology and Molecular Medicine (CABMM), University of Zurich, Zurich, Switzerland. Electronic address: peter.kronen@vas-int.com.
authors.forename: Peter W
authors.initials: PW
authors.lastname: Kronen
mesh_terms: D000281:Administration, Intranasal / Q000379:methods; D058647:Adrenergic alpha-2 Receptor Agonists / Q000008:administration & dosage* / Q000009:adverse effects; D000758:Anesthesia / Q000379:methods / Q000662:veterinary*; D019162:Anesthetics, Combined / Q000008:administration & dosage / Q000009:adverse effects; D018685:Anesthetics, Inhalation / Q000008:administration & dosage* / Q000009:adverse effects; D000818:Animals; D002047:Buprenorphine / Q000008:administration & dosage; D005260:Female; D006339:Heart Rate; D007530:Isoflurane; D007649:Ketamine / Q000008:administration & dosage* / Q000009:adverse effects; D008297:Male; D020926:Medetomidine / Q000008:administration & dosage* / Q000009:adverse effects; D009292:Narcotic Antagonists / Q000008:administration & dosage; D056888:Patient Positioning / Q000009:adverse effects / Q000662:veterinary*; D011446:Prospective Studies; D011817:Rabbits
chemical_list: D058647:Adrenergic alpha-2 Receptor Agonists; D019162:Anesthetics, Combined; D018685:Anesthetics, Inhalation; D009292:Narcotic Antagonists; D002047:Buprenorphine; D007649:Ketamine; D007530:Isoflurane; D020926:Medetomidine
keywords: S(+)-ketamine; endotracheal intubation; intranasal; ketamine; medetomidine; rabbit