Effects of hydromorphone alone and combined with medetomidine-vatinoxan or dexmedetomidine on alfaxalone induction dose and mean arterial pressure in dogs anesthetized with sevoflurane

Lily V Davis; Chiara E Hampton; Stephanie A Kleine; Christopher K Smith; Genevieve Bussières; Xiaojuan Zhu; Reza Seddighi

doi:10.1016/j.vaa.2024.10.138

Effects of hydromorphone alone and combined with medetomidine-vatinoxan or dexmedetomidine on alfaxalone induction dose and mean arterial pressure in dogs anesthetized with sevoflurane

Vet Anaesth Analg. 2024 Oct 24:S1467-2987(24)00331-3. doi: 10.1016/j.vaa.2024.10.138. Online ahead of print.

Authors

Lily V Davis¹, Chiara E Hampton², Stephanie A Kleine³, Christopher K Smith³, Genevieve Bussières³, Xiaojuan Zhu⁴, Reza Seddighi²

Affiliations

¹ Department of Large Animal Clinical Sciences, College of Veterinary Medicine, University of Tennessee, Knoxville, TN, USA. Electronic address: Lilyvdav@gmail.com.
² Department of Large Animal Clinical Sciences, College of Veterinary Medicine, University of Tennessee, Knoxville, TN, USA.
³ Department of Small Animal Clinical Sciences, College of Veterinary Medicine, University of Tennessee, Knoxville, TN, USA.
⁴ Office of Innovative Technologies, University of Tennessee, Knoxville, TN, USA.

PMID: 39592323
DOI: 10.1016/j.vaa.2024.10.138

Abstract

Objective: To evaluate the dose of alfaxalone needed for induction of anesthesia following sedation with medetomidine-vatinoxan plus hydromorphone (MVH), dexmedetomidine plus hydromorphone (DH), or hydromorphone (H) alone. A secondary objective included evaluating selected cardiopulmonary variables before, during, and after sedation and general anesthesia with sevoflurane in healthy dogs.

Study design: Prospective, randomized, masked, crossover.

Animals: Eight healthy Beagle dogs, 3-4 years old.

Methods: All dogs received three intramuscular (IM) treatments: H (0.1 mg kg^-1), DH (0.005 mg kg^-1 + 0.1 mg kg^-1, respectively), or MVH (0.01 mg kg^-1 + 0.2 mg kg^-1 + 0.1 mg kg^-1, respectively) at least 6 days apart. General anesthesia was induced with alfaxalone 20 minutes after treatment administration and maintained for 60 minutes with 2.8% sevoflurane (expired). Sedation scores, selected cardiopulmonary variables, and recovery scores were measured before, during, and after anesthesia at selected timepoints. Mixed-effects ANOVA and ANOVA on ranks were used to evaluate differences between treatments, time, and their interaction, and Tukey-Kramer method was used for post hoc analysis (p < 0.05). Data are presented as mean ± SD or median (range).

Results: Dogs given MVH required a lower dose of alfaxalone for induction of anesthesia (0.77 ± 0.4 mg kg^-1) compared to DH and H (1.16 ± 0.34 mg kg^-1; p = 0.02, 1.13 ± 0.18 mg kg^-1; p = 0.02), and had a higher incidence (50%; p = 0.038) and longer duration [median; 10 (0-35) minutes] of hypotension during sevoflurane anesthesia compared to H [0%; 0 (0-0) minutes; p = 0.040] but not DH (p = 0.272).

Conclusions and clinical relevance: Premedication with MVH provided the greatest alfaxalone-sparing effect. However, this treatment was associated with lower arterial pressures and clinically relevant hypotension. Off-label use of medetomidine-vatinoxan before sevoflurane-based anesthesia should be used with caution due to a high incidence of hypotension.

Keywords: alfaxalone; dexmedetomidine; hydromorphone; medetomidine; sevoflurane; vatinoxan.