Echocardiographic effects of a medetomidine-vatinoxan combination for sedating dogs without previously diagnosed heart disease.

Medetomidine-vatinoxan provides reliable sedation but significantly alters echocardiographic variables, complicating cardiac assessment.

This prospective within-subject clinical study evaluated the sedative and echocardiographic effects of intramuscular medetomidine (1 mg/m²) combined with vatinoxan (20 mg/m²) in 17 healthy client-owned dogs undergoing elective diagnostic procedures. Sedation onset occurred at approximately 4 minutes, with maximum sedation scores (12/12) reached by 12 minutes, allowing echocardiographic examination with minimal restraint and facilitating venous catheterization. Heart rate significantly decreased from 128 to 74 beats/minute post-injection, while noninvasive arterial blood pressure remained unchanged, consistent with vatinoxan's peripheral alpha-2 antagonist profile that mitigates the hypertensive response typically seen with medetomidine alone. However, significant echocardiographic changes were observed: ejection fraction declined from 71% to 53%, fractional shortening from 42% to 32%, and end-systolic volume increased from 11.6 to 15.8 mL. Diastolic function parameters were also affected, with reductions in transmitral early diastolic velocity (E wave) and annular early diastolic velocity (e'), along with prolongation of isovolumic relaxation time. These findings indicate that despite vatinoxan's peripheral vascular effects, medetomidine-vatinoxan still induces notable alterations in both systolic and diastolic cardiac function in clinically healthy dogs. Veterinary clinicians should account for these drug-induced echocardiographic changes when interpreting cardiac imaging performed under this sedation protocol, as they may confound the assessment of true cardiac function.

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