title: Effects of ketamine, propofol, or thiopental administration on intraocular pressure and qualities of induction of and recovery from anesthesia in horses.
abstract: OBJECTIVE
  To assess the effects of ketamine hydrochloride, propofol, or compounded thiopental sodium administration on intraocular pressure (IOP) and qualities of induction of and recovery from anesthesia in horses.
  
  
  METHODS
  6 healthy adult horses.
  
  
  METHODS
  Horses were sedated with xylazine hydrochloride (0.5 mg/kg), and anesthesia was induced with guaifenesin followed by ketamine (2 mg/kg), propofol (3 mg/kg), or thiopental (4 mg/kg) in a crossover study with ≥ 1 week between treatments. For each horse, IOP in the right eye was measured with a handheld applanation tonometer before and after xylazine administration, at the time of recumbency, and every 3 minutes after induction of anesthesia until spontaneous movement was observed. Cardiorespiratory responses and venous blood measurements were recorded during anesthesia. Induction of and recovery from anesthesia were subjectively evaluated by investigators who were unaware of the anesthetic treatment of each horse. Data were analyzed via a repeated-measures ANOVA with Holm-Ŝidák post hoc comparisons.
  
  
  RESULTS
  Compared with findings after xylazine administration (mean ± SD, 17 ± 3 mm Hg), thiopental decreased IOP by 4 ± 23%, whereas propofol and ketamine increased IOP by 8 ± 11% and 37 ± 16%, respectively. Compared with the effects of ketamine, propofol and thiopental resulted in significantly lower IOP at the time of recumbency and higher heart rates at 3 minutes after induction of anesthesia. No other significant differences among treatments were found.
  
  
  CONCLUSIONS
  These findings support the use of thiopental or propofol in preference to ketamine for horses in which increases in IOP should be minimized.
authors.affiliation: Department of Surgical and Radiological Sciences, School of Veterinary Medicine, University of California-Davis, CA 95616, USA.
authors.forename: Tatiana H
authors.initials: TH
authors.lastname: Ferreira
authors.forename: Robert J
authors.initials: RJ
authors.lastname: Brosnan
authors.forename: Yael
authors.initials: Y
authors.lastname: Shilo-Benjamini
authors.forename: Stephanie B
authors.initials: SB
authors.lastname: Moore
authors.forename: Steven R
authors.initials: SR
authors.lastname: Hollingsworth
mesh_terms: D000762:Anesthesia Recovery Period; D000778:Anesthetics, Dissociative / Q000009:adverse effects / Q000494:pharmacology; D018686:Anesthetics, Intravenous / Q000009:adverse effects / Q000494:pharmacology; D000818:Animals; D018592:Cross-Over Studies; D005260:Female; D006736:Horses; D007429:Intraocular Pressure / Q000187:drug effects*; D007649:Ketamine / Q000008:administration & dosage / Q000009:adverse effects / Q000494:pharmacology*; D008297:Male; D015742:Propofol / Q000008:administration & dosage / Q000009:adverse effects / Q000494:pharmacology*; D013874:Thiopental / Q000008:administration & dosage / Q000009:adverse effects / Q000494:pharmacology*
chemical_list: D000778:Anesthetics, Dissociative; D018686:Anesthetics, Intravenous; D007649:Ketamine; D013874:Thiopental; D015742:Propofol