title: Comparison of sedation and mechanical antinociception induced by intravenous administration of acepromazine and four dose rates of dexmedetomidine in donkeys.
abstract: OBJECTIVE
  To assess and compare the sedative and antinociceptive effects of four dosages of dexmedetomidine in donkeys.
  
  
  METHODS
  Randomized, controlled, crossover, Latin-square, blinded study.
  
  
  METHODS
  Six healthy, castrated, adult, standard donkeys.
  
  
  METHODS
  Dexmedetomidine (2, 3, 4 and 5 μg kg-1; D2, D3, D4 and D5), acepromazine (0.1 mg kg-1) and saline were administered intravenously to each donkey and a 1 week interval was allowed between successive trials on each animal. Sedation scores (SS) and head heights above ground (HHAG) were used to assess sedation and mechanical nociceptive threshold (MNT) testing to assess antinociception over 120 minutes post-treatment. Areas under the curve (AUC) for 0-30, 30-60 and 60-120 minutes were computed to compare the effect of treatments.
  
  
  RESULTS
  SS-AUC0-30values were larger for D4 and D5, and SS-AUC30-60values were larger for D5 than for saline. All dexmedetomidine treatments produced lower HHAG-AUC0-30and HHAG-AUC30-60values, and acepromazine produced lower HHAG AUC60-120values than did saline. For MNT, D3, D4 and D5 increased AUC0-30and AUC30-60values compared with saline and also AUC0-30values compared with D2 and acepromazine. Smaller MNT-AUC30-60values were obtained with D2 than with D4 and D5, with D3 than with D5, and with acepromazine than with D4 and D5.
  
  
  CONCLUSIONS
  Dexmedetomidine induced sedation and dosage-dependent mechanical antinociception. Larger dexmedetomidine dose rates were required to induce antinociception than sedation. Furthermore, the antinociception induced by dexmedetomidine was of shorter duration than its sedation. For minor painful procedures on standing donkeys, D5 may be clinically useful to provide sedation and analgesia.
authors.affiliation: Department of Biomedical Sciences, Ross University School of Veterinary Medicine, Basseterre, Saint Kitts and Nevis. Electronic address: madrigal@unam.mx.
authors.forename: Ignacio
authors.initials: I
authors.lastname: Lizarraga
authors.affiliation: Department of Biomedical Sciences, Ross University School of Veterinary Medicine, Basseterre, Saint Kitts and Nevis.
authors.forename: Fernanda
authors.initials: F
authors.lastname: Castillo-Alcala
authors.affiliation: Department of Biomedical Sciences, Ross University School of Veterinary Medicine, Basseterre, Saint Kitts and Nevis.
authors.forename: Lauren S
authors.initials: LS
authors.lastname: Robinson
mesh_terms: D000075:Acepromazine / Q000008:administration & dosage*; D061605:Administration, Intravenous / Q000662:veterinary; D058647:Adrenergic alpha-2 Receptor Agonists / Q000008:administration & dosage*; D000758:Anesthesia / Q000379:methods / Q000662:veterinary*; D000818:Animals; D019540:Area Under Curve; D018592:Cross-Over Studies; D020927:Dexmedetomidine / Q000008:administration & dosage*; D018397:Equidae; D006993:Hypnotics and Sedatives / Q000008:administration & dosage*; D059225:Nociception; D010147:Pain Measurement / Q000379:methods / Q000662:veterinary
chemical_list: D058647:Adrenergic alpha-2 Receptor Agonists; D006993:Hypnotics and Sedatives; D000075:Acepromazine; D020927:Dexmedetomidine
keywords: analgesia; dexmedetomidine; donkey; mechanical nociception; sedation