Medetomidine-vatinoxan is associated with a higher proportion of hypotension than dexmedetomidine in anesthetized dogs: a retrospective, matched-cohort study.

Objective: To compare clinical parameters and medical interventions during the first hour of inhalant anesthesia in dogs administered medetomidine-vatinoxan (Zenalpha [ZEN]) versus dexmedetomidine (DEX) as IM preanesthetic agents. Methods: Medical records were searched to identify dogs premedicated with ZEN between August 2022 and January 2025. Dogs administered DEX between July 2021 and May 2026 were then identified and matched with α2-adrenergic receptor agonist dose equivalence prioritized. Generalized estimating equation models were constructed to assess associations between variables of interest and premedication type, while accounting for repeated measurements within paired matched sets. Results: The ZEN group included 24 dogs (ZEN dose median, 10 μg/kg; range, 5 to 26 μg/kg), whereas the DEX group included 48 dogs (DEX dose median, 5 μg/kg; range, 3 to 10 μg/kg), with no differences between groups. Compared with DEX, premedication with ZEN was associated with an 18 beats/min higher heart rate, whereas mean arterial pressure was 19 mm Hg lower. Dogs receiving ZEN had 9.3-fold greater odds of receiving an IV fluid bolus and 6.8-fold greater odds of vasopressor administration. No differences were detectable between groups in IV interventions administered for a light plane of anesthesia. Conclusions: Findings indicated ZEN was associated with intraoperative hypotension in dogs during the first hour of volatile anesthesia, despite significantly higher heart rates. This effect translated into a significantly greater need for hemodynamic intervention. Clinical Relevance: The effects of ZEN on arterial blood pressure warrant careful hemodynamic monitoring and preparedness to provide blood pressure support in dogs undergoing inhalant anesthesia.