Anesthesia of Agoutis (Dasyprocta prymnolopha) with Dextroketamine and Midazolam

Abstract

 Background: Research has increasingly focused on wild animals, and this requires the use of chemical restraints that are safe for both the species and the team involved. Dextroketamine is the levorotatory ketamine isomer that has been used on domestic species as an alternative that is more potent and safer than the racemic form. Midazolam is a benzodiazepine that induces muscle relaxation and minimal cardiorespiratory changes. The purpose of this study was to determine whether a combination of dextroketamine and midazolam can be safely used for the chemical restraint of agoutis (Dasyprocta prymnolopha), and the effects of this protocol on physiological and anesthetic parameters. Materials, Methods & Results: This study was carried out under conditions similar to those found for wild animals in captivity or in zoos. A pre-evaluation was also made to compare the baseline values of this study with those of other studies on the same species. Nine healthy adult agoutis were used, weighing between 1.5 kg and 2 kg. All the parameters were evaluated and recorded before the drugs were applied, and this was considered the baseline moment (M0). The dextroketamine and midazolam combination was then administered intramuscularly, in the same syringe, in dosages of 15 mg/kg and 0.5 mg/kg, respectively. Successive evaluations were made every 10 min over a period of 40 min (M10, M20, M30 and M40). The latency stage of anesthesia, effective stage and recovery stage were observed. Heart rate (HR) and breathing frequency (f), body temperature (BT), systolic blood pressure (SBP), peripheral oxygen saturation (SpO2) and electrocardiogram were recorded. HR and SBP showed no significant difference between moments. Breathing frequency (f) showed a significant decline at M10 and M20 when compared to baseline values (P < 0.05). BT decreased from the moment the drugs were administered until the end of the experimental period, with a significant difference between M0 and M40, and M10 and M40 (P < 0.05). SpO2 decreased significantly at M10 and M20 when compared to baseline values (P < 0.01). There was no significant difference in the duration and amplitude of the P wave or in the duration of the QRS complex, QT interval and amplitude of the R wave. Regarding the PR interval, there was a significant difference only at M40 when compared to baseline values (P < 0.05). No arrhythmia was observed. An evaluation of the effects of anesthesia indicated that the animals had an average latency stage of 2 min, an effective stage of 87 min, and an average recovery stage of 111 min. Adverse effects observed during the anesthetic recovery period consisted of tearing, salivation, tongue protrusion, vocalization and chewing reflex. Discussion: The results indicated that the association of anesthetic drugs under study caused minimal changes in the animals’ physiological parameters, except for the breathing frequency (f), which declined considerably, resulting in a reduction in SpO2, which was compensated during the study. In addition, there was a rapid onset of restraint and a satisfactory duration. Thus, from the cardiorespiratory standpoint, the combination of dextroketamine and midazolam in the doses used provides a safe anesthetic protocol for agoutis (Dasyprocta prymnolopha) and can be used for the chemical restraint of these animals for the performance of non-invasive and short-term procedures.