The impact of intravenous detomidine and vatinoxan on echocardiographic findings of left ventricle in horses

Adequate image quality in equine echocardiography requires stillness from the patient. Sedation with alpha₂-adrenoceptor agonists may alter cardiac measurements. An alpha₂‐adrenoceptor antagonist, vatinoxan does not cross the blood-brain-barrier. Therefore, it alleviates the peripheral effects of detomidine, while the central sedative effects remain unaffected. This makes vatinoxan a potential addition to sedative protocols for echocardiography in restless horses.

Standard transthoracic M-mode echocardiography of the left ventricle was performed to evaluate internal diameter in systole and diastole (LVIDs, LVIDd) and fractional shortening (FS) at the level of papillary muscles in 6 horses (median age 13 years; range 5-21) without clinical evidence of cardiac disease. Horses with an audible murmur ≥ 2/6, elevated cardiac troponin I or evidence of general illness were excluded. The echocardiographic examination was performed pre-sedation and 10 minutes post-sedation with detomidine HCl 10 µg/kg and vatinoxan HCl 200 µg/kg IV. The effects of sedation were evaluated with T-test or Wilcoxon signed rank test.

Median heart rate was 40 (range 36-44) pre-sedation and 38 (range 36-42) 15 minutes post-sedation. Mean ± SD LVIDs, LVIDd and FS were 5.32 cm ± 0.48, 9.84 cm ± 0.72, 45.92% ± 2.91 pre-sedation and 5.27cm ± 0.66, 9.54 cm ± 0.69, 44.62% ± 6.52 post-sedation, respectively. No significant differences were noticed between any pre- and post-sedation values.

In conclusion, pre- and post-sedation HR, LVID and FS values were comparable in horses sedated with detomidine and vatinoxan. Echocardiographic measurements might be reliably performed under detomidine-vatinoxan sedation in horses.