Professor QTest Labs Columbus, Ohio, United States
Abstract: Background Zenalpha® (medetomidine-vatinoxan) is a sedative-analgesic for dogs containing the novel molecule, vatinoxan, which counteracts medetomidine’s cardiovascular depressive effects. To date, the use of Zenalpha® has been investigated in healthy dogs and its safe use in cardiac patients is to be determined.
Hypothesis/Objectives The objective was to compare the cardiovascular effects of Zenalpha® to dexmedetomidine in dogs with mild to moderate heart failure.
Animals Seven purpose-bred, tachy-paced Beagles with ejection fraction of 45% ± 5% including mild concomitant left-ventricular enlargement.
Methods In this blinded crossover study each dog received Zenalpha® (0.25 mg/m2 medetomidine and 5 mg/m2 vatinoxan) or dexmedetomidine (0.25 mg/m2) intramuscularly. Heart rate (HR), ECG and mean arterial pressure (MAP) were recorded and cardiac output measured at intervals until 120 min post-treatment. Differences between treatments and baseline were evaluated with repeated measures analysis (p < 0.05).
Results Compared to dexmedetomidine stroke volume (SVI) and cardiac indices (CI) were significantly higher with Zenalpha® until 60 and 120 min post-treatment, respectively. SVI did not decrease significantly from baseline with Zenalpha®. CI and HR decreased significantly from baseline with both treatments. With Zenalpha® CI and HR returned to baseline at 120 and 90 min, respectively, and HR was significantly higher than with dexmedetomidine at 90 and 120 min post-treatment. Compared to dexmedetomidine MAP was significantly lower from 15 to 90 min post-treatment with Zenalpha® remaining below baseline until 120 min.
Conclusions and clinical importance In comparison to dexmedetomidine Zenalpha® caused less detrimental cardiovascular changes in dogs with mild to moderate heart failure.
