(C48) Effects of Medetomidine-Vatinoxan on Echocardiographic Examination in Ventricular Tachy-paced Dogs with Mild Heart Failure

Abstract:

Background
Medetomidine-vatinoxan combination (Zenalpha^®) is a novel sedative-analgesic for dogs causing fewer adverse cardiovascular changes compared to traditional alpha₂-agonists. Fractious, fearful, or excited cardiac patients requiring considerable manual restraint to perform echocardiography could benefit from procedural sedation if there was a safe and efficacious sedative option that would not interfere with the interpretation of the results.

Hypothesis/Objectives
The objective was to compare the echocardiographic effects of medetomidine-vatinoxan to dexmedetomidine in dogs with mild heart failure.

Animals
Seven purpose-bred, tachy-paced Beagles with ejection fraction of 49% ± 4% including mild concomitant left-ventricular enlargement.

Methods
In this blinded crossover study each dog received 0.25 mg/m² medetomidine and 5 mg/m² vatinoxan or 0.25 mg/m² dexmedetomidine intramuscularly. A transthoracic echocardiographic examination was performed at baseline and 15, 30, and 45 minutes post-treatment.

Results
End diastolic and systolic volumes were significantly lower at 45 minutes and left ventricular diameter during diastole and systole significantly smaller at each observation point with medetomidine-vatinoxan in comparison to dexmedetomidine. Ejection fraction and fractional shortening remained significantly higher at 30 and 45 minutes with medetomidine-vatinoxan than with dexmedetomidine. Left atrial diameter to aortic diameter ratio was significantly lower with medetomidine-vatinoxan than with dexmedetomidine at 15 minutes. The only significant change compared to baseline with medetomidine-vatinoxan was decreased left ventricular diameter during diastole at 45 minutes. With dexmedetomidine most variables changed significantly from baseline.

Conclusions and clinical importance
Medetomidine-vatinoxan caused less echocardiographic changes in dogs with mild heart failure in comparison to dexmedetomidine, and most variables remained close to baseline values.