Anesthesia and Braquial Plexus Block in Nine-Banded Armadillo (Dasypus novemcinctus)-Case Report

Introduction

The nine-banded armadillo (Dasypus novemcinctus) is currently classified as a ‘’least concern’’ species in the conservation status of biological species, it is a medium- sized animal with nocturnal and lonely habits and is found in North, Central and South America which makes it the one of the most common of the armadillos [1]. A few armadillo’s (Nine-Banded, Six-Banded (Euphractus sexcinctus), three-banded (Tolypeutes matacus), long-nose (Dasypus kappleri), Andean hairy armadillo (Chaetophractus nationi), southern naked-tailed (Cabassous unicinctus) and Giant (Priodontes maximus) anesthetic procedures are described in the literature, most of them using dissociative protocols, including quetamine or tiletamine + zolazepam associated with xylazine, detomidine, butorfanol or midazolam [2, 3, 4, 5, 6, 7]. One particular case of a P. maximus was using Isoflurane by mask for maintaining the anesthesia [8].

No reports were found about laryngeal mask use in these species and also we didn’t find any reports on using regional and local anesthesia, only one phrase emphasizing that anatomical features of these species can make it’s use difficult [8].

This work aims to describe the anesthetic protocol and blockage of the brachial plexus at a surgical procedure of osteosynthesis.

Body of Paper

A male nine-banded armadillo, weighing 3.4kg was rescued and brought to the zoo after possibly being runned over by a vehicle. Radiographic exams were performed and revealed complete radioulnar fracture of the left thoracic limb (Figure 1). Until the surgery, the animal received meloxicam (0.1 mg/kg), tramadol (2mg/kg) and dipyrone (25 mg/kg).

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For the preanesthetic medication, an association of methadone at 0,2 mg/kg, S-cetamine at 10 mg/kg and midazolam at 0.2 mg/kg by Intramuscular route. Venous access was made in the internal saphenous vein with a 24G catheter. The anesthetic induction was done with 1% isoflurane and the animal was kept with a laryngeal mask of 1.0 sterile silicon, with cuff, at spontaneous ventilation, non- rebreathing system (baraka) and 2 l/min O2, isoflurane and fluid therapy at a 1-2 ml/kg.h Table 1.

As an alternative to endotracheal tube, the laryngeal mask is an apparatus that allows easy access to the airway [9, 10, 11, 12]. The human laryngeal mask has varied sizes, and the size 1 was utilized in this case. The mask provides adequate maintenance of the airways under spontaneous or controlled respiration and reduces the possibility of trauma caused by the introduction of the endotracheal tube at the laryngeal region. In this case, the mask was efficient, properly occluding the glottis, as verified at the monitor through pulse oximetry, capnography and capnometry. The low value at pulse oximetry may be due to the laryngeal mask applying a little pressure at the sublingual artery, such as in rabbits [13].

Parameters such as echocardiogram, oxygen saturation, respiratory frequency, end-tidal carbon dioxide concentration, systolic and diastolic arterial pressure, temperature were checked through a multiparameter monitor (Table 2). Furthermore, eye lubrication was monitored during the entire surgical procedure and eye drops were used to lubricate within ten minutes intervals.

For the brachial plexus block, lidocaine was used to promote analgesia of the thoracic member distal to the spaculohumeral joint. The identification of the blockage was realized through palpation of the anatomical region associated with peripheral nerve stimulator (PNS). The anatomy of the nine-banded armadillo members (short, strong and hidden in carapace) makes the palpation and identification of the anatomics difficult, that is why PNS was helpful in this case. This equipment, with the aid of a specific needle for neurolocalization, emits electrical pulses to localize the desired nerve and muscular responses that occur when approached. The moment that the contraction involves the extension from the distal part of the member, stimulating the radial nerve, an aspersion is performed to check vascular puncture, and if it is not identified, the local anesthetic is injected [14].

Postoperative medication used were meloxicam at 0.2 mg/kg, dypirone at 25 mg/kg, enrofloxacin at 0.05 mg/kg and flumazenil at 0.05 mg/kg by subcutaneous route

Conclusion

Despite the unknown minimum alveolar concentration of isoflurane in nine-banded armadillo, we concluded that, the use of brachial plexus blockage and the cardiovascular stability suggest that this maneuver proved to be effective in the analgesia and decrease in isoflurane use. The reversal of midazolam with flumazenil added to a quick recovery. The human laryngeal mask also proved to be effective in the management of the airways in the armadillo.

Acknowledgement

The authors would like to thank Zoológico Municipal de Canoas for their support. We also thank Plenavet Radiologia Móvel for the radiographs.