Investigation of selected respiratory effects of (dex)medetomidine in healthy Beagles

Tekla Pleyers; Olivier Levionnois; Joëlle Siegenthaler; Claudia Spadavecchia; Mathieu Raillard

doi:10.1016/j.vaa.2020.05.001

Investigation of selected respiratory effects of (dex)medetomidine in healthy Beagles

Vet Anaesth Analg. 2020 Sep;47(5):667-671. doi: 10.1016/j.vaa.2020.05.001. Epub 2020 May 14.

Authors

Tekla Pleyers¹, Olivier Levionnois¹, Joëlle Siegenthaler¹, Claudia Spadavecchia¹, Mathieu Raillard²

Affiliations

¹ Anaesthesiology section, Department of Clinical Veterinary Sciences, Vetsuisse Faculty, University of Berne, Berne, Switzerland.
² Anaesthesiology section, Department of Clinical Veterinary Sciences, Vetsuisse Faculty, University of Berne, Berne, Switzerland; The University of Sydney, Faculty of Science, School of Veterinary Science, The University of Sydney, NSW, Australia. Electronic address: mathieu_raillard@yahoo.it.

PMID: 32792270
DOI: 10.1016/j.vaa.2020.05.001

Abstract

Objective: To investigate the effects of sedative doses of intravenous (IV) medetomidine (MED) or dexmedetomidine (DEX) on selected respiratory variables in dogs.

Study design: Randomized, blinded, crossover study.

Animals: A total of eight healthy adult research Beagles.

Methods: Dogs breathing room air had an electrical impedance tomography belt placed around the chest and were maintained in right lateral recumbency. Respiratory rate (f_R) in movements minute^-1 (mpm) and changes in thoracic impedance (ΔZ) in arbitrary units (AU) were recorded for 120 seconds before (T0) and exactly 10 minutes (T10) after the administration of IV DEX (10 μg kg^-1) or MED (20 μg kg^-1), with a minimum washout period of 10 days between treatments. Minute ΔZ (ΔZ˙) was calculated by multiplying median ΔZ with f_R. Data are presented as median (interquartile range). Significance for an overall effect of drugs (DEX versus MED) or treatment (T0 versus T10) was quantified with a two-way analysis of variance for repeated measures, followed by, when appropriate, Wilcoxon's signed rank test for each factor.

Results: Overall, f_R decreased from 26 (22-29) mpm at T0 to 13 (10-21) mpm at T10 (p = 0.003) and ΔZ increased from 1.133 (0.856-1.599) AU at T0 to 1.650 (1.273-2.813) AU at T10 (p = 0.007), but ΔZ˙ did not change [30.375 (23.411-32.445) AU minute^-1 at T0 and 30.581 (22.487-35.091) AU minute^-1 at T10]. There was no difference between DEX and MED. Most dogs developed a peculiar breathing pattern characterized by clusters of breaths followed by short periods of apnoea.

Conclusions and clinical relevance: Both drugs caused a change in breathing pattern, reduction in f_R and increase in ΔZ but did not affect ΔZ˙. It is likely that (dex)medetomidine resulted in reduction in f_R and increase in tidal volume without impacting minute volume.

Keywords: dexmedetomidine; dogs; electrical impedance tomography (EIT); medetomidine; respiratory; α(2)-adrenoreceptor agonists.

Publication types

Randomized Controlled Trial, Veterinary

MeSH terms

Animals
Cross-Over Studies
Dexmedetomidine / pharmacology*
Dogs*
Female
Hypnotics and Sedatives / pharmacology*
Male
Medetomidine / pharmacology*
Respiratory Physiological Phenomena / drug effects*

Substances

Hypnotics and Sedatives
Dexmedetomidine
Medetomidine