title: Effects of medetomidine and xylazine on intraocular pressure and pupil size in healthy Beagle dogs.
abstract: OBJECTIVE
  To determine the effects of intramuscular (IM) administration of medetomidine and xylazine on intraocular pressure (IOP) and pupil size in normal dogs.
  
  
  METHODS
  Prospective, randomized, experimental, crossover trial.
  
  
  METHODS
  Five healthy, purpose-bred Beagle dogs.
  
  
  METHODS
  Each dog was administered 11 IM injections of, respectively: physiological saline; medetomidine at doses of 5, 10, 20, 40 and 80 μg kg(-1), and xylazine at doses of 0.5, 1.0, 2.0, 4.0 and 8.0 mg kg(-1). Injections were administered at least 1 week apart. IOP and pupil size were measured at baseline (before treatment) and at 0.25, 0.50, 0.75, 1, 2, 3, 4, 5, 6, 7, 8 and 24 hours post-injection.
  
  
  RESULTS
  A significant decrease in IOP was observed at 6 hours after 80 μg kg(-1) medetomidine compared with values at 0.25 and 0.50 hours, although there were no significant changes in IOP from baseline. In dogs treated with 8.0 mg kg(-1) xylazine, significant reductions in IOP were observed at 4 and 5 hours compared with that at 0.25 hours after administration. In dogs treated with 5, 10, 20 and 40 μg kg(-1) medetomidine and 0.5, 1.0 and 2.0 mg kg(-1) xylazine, there were no significant changes in IOP. Pupil size did not change significantly after any of the medetomidine or xylazine treatments compared with the baseline value.
  
  
  CONCLUSIONS
  Low or moderate doses of medetomidine or xylazine did not induce significant changes in IOP or pupil size. In contrast, high doses of medetomidine or xylazine induced significant changes up to 8 hours after treatment, but values remained within the normal canine physiological range. The results of this study suggest a lack of significant change in IOP and pupil size in healthy dogs administered low or moderate doses of xylazine or medetomidine.
authors.affiliation: Laboratory of Veterinary Nursing and Medication, Department of Comparative Animal Science, College of Life Science, Kurashiki University of Science and the Arts, Kurashiki, Japan.|Veterinary Teaching Hospital, Kurashiki University of Science and the Arts, Kurashiki, Japan.
authors.forename: Teppei
authors.initials: T
authors.lastname: Kanda
authors.affiliation: Laboratory of Veterinary Nursing and Medication, Department of Comparative Animal Science, College of Life Science, Kurashiki University of Science and the Arts, Kurashiki, Japan.
authors.forename: Ayano
authors.initials: A
authors.lastname: Iguchi
authors.affiliation: Laboratory of Veterinary Nursing and Medication, Department of Comparative Animal Science, College of Life Science, Kurashiki University of Science and the Arts, Kurashiki, Japan.
authors.forename: Chieko
authors.initials: C
authors.lastname: Yoshioka
authors.affiliation: Laboratory of Veterinary Nursing and Medication, Department of Comparative Animal Science, College of Life Science, Kurashiki University of Science and the Arts, Kurashiki, Japan.
authors.forename: Haruka
authors.initials: H
authors.lastname: Nomura
authors.affiliation: Laboratory of Veterinary Nursing and Medication, Department of Comparative Animal Science, College of Life Science, Kurashiki University of Science and the Arts, Kurashiki, Japan.
authors.forename: Kanako
authors.initials: K
authors.lastname: Higashi
authors.affiliation: Laboratory of Veterinary Nursing and Medication, Department of Comparative Animal Science, College of Life Science, Kurashiki University of Science and the Arts, Kurashiki, Japan.
authors.forename: Minami
authors.initials: M
authors.lastname: Kaya
authors.affiliation: Laboratory of Veterinary Nursing and Medication, Department of Comparative Animal Science, College of Life Science, Kurashiki University of Science and the Arts, Kurashiki, Japan.
authors.forename: Rie
authors.initials: R
authors.lastname: Yamamoto
authors.affiliation: Laboratory of Veterinary Nursing and Medication, Department of Comparative Animal Science, College of Life Science, Kurashiki University of Science and the Arts, Kurashiki, Japan.
authors.forename: Tomoko
authors.initials: T
authors.lastname: Kuramoto
authors.affiliation: Veterinary Teaching Hospital, Kurashiki University of Science and the Arts, Kurashiki, Japan.
authors.forename: Toshinori
authors.initials: T
authors.lastname: Furukawa
mesh_terms: D058647:Adrenergic alpha-2 Receptor Agonists / Q000008:administration & dosage / Q000494:pharmacology*; D000818:Animals; D018592:Cross-Over Studies; D004285:Dogs; D004305:Dose-Response Relationship, Drug; D007273:Injections, Intramuscular / Q000662:veterinary; D007429:Intraocular Pressure / Q000187:drug effects*; D008297:Male; D020926:Medetomidine / Q000008:administration & dosage / Q000494:pharmacology*; D012025:Reflex, Pupillary / Q000187:drug effects*; D014991:Xylazine / Q000008:administration & dosage / Q000494:pharmacology*
chemical_list: D058647:Adrenergic alpha-2 Receptor Agonists; D014991:Xylazine; D020926:Medetomidine
keywords: dog; intraocular pressure; medetomidine; pupil size; xylazine