The impact of Vatinoxan, a peripheral α2-adrenoceptor antagonist, on medetomidine –ketamine-midazolam immobilization in Patagonian Maras (Dolichotis patagonum)

Abstract Objective To compare the cardiovascular and ventilatory effects, immobilization quality and the effects on tissue perfusion of a medetomidine-ketamine-midazolam combination with or without vatinoxan (MK-467), a peripherally acting α2-adrenoceptor antagonist. Study design Randomized, blinded cross-over study. Animals A group of nine healthy Patagonian maras (Dolichotis patagonum). Methods Maras were immobilized twice with either: 1) medetomidine hydrochloride (0.1 mg kg-1) + ketamine (5 mg kg-1) + midazolam (0.1 mg kg-1) (MKM) + saline, or with 2) MKM + vatinoxan hydrochloride (0.8 mg kg-1), administered intramuscularly. Drugs were mixed in the same syringe. At 20, 30 and 40 minutes after injection, invasive blood pressure, heart rate, respiration rate, end-tidal CO2, haemoglobin oxygen saturation, arterio-venous oxygen content difference, and muscle oxygenation were measured. Muscle tone, jaw tone, spontaneous blinking and palpebral reflex were evaluated. Times to initial effect, recumbency, initial arousal and control of the head were recorded. Paired t-test, Wilcoxon matched-pairs signed rank test and ANOVA were used to compare protocols. p Results Vatinoxan significantly reduced systolic (p = 0.0002), mean (p 120 mmHg) while with vatinoxan, four animals were hypotensive (MAP Conclusion and clinical relevance In Patagonian maras, vatinoxan attenuated the increase in blood pressure induced by medetomidine. Muscle and jaw tone were more frequently present with MKM, indicating that quality of immobilization with vatinoxan was more profound.