Abstract Introduction

The white-nosed coatimundi (Nasua narica) is one of two members of the genus Nasua in the raccoon family, Procyonidae. With the exception of a few reports, detailed published data regarding species-specific anesthesia protocols and physiologic parameters for the coati genus is lacking. Most published protocols include high doses of dissociative agents, ketamine or tiletamine in combination with zolezepam.^1,4,6 These agents have been associated with inadequate neuromuscular relaxation, tonic/clonic convulsions, and prolonged, rough recoveries. Use of these agents is less desirable because of the lack of specific reversal agents.

Alpha₂-adrenergic receptor agonists have been used in combination with ketamine to anesthetize a wide array of non-domestic mammal species.³ The combination of α₂-adrenergic receptor agonist medetomidine and its specific receptor antagonist, atipamezole, has the advantage of increased α₂-adrenergic receptor specificity and excellent reversibility leading to rapid, smooth recoveries. The addition of medetomidine to ketamine regimens has substantially reduced ketamine dosages needed, diminishing many of the adverse effects seen with higher doses of dissociative agents. The addition of butorphanol to medetomidine-ketamine protocols has been reported in several carnivore species.^5,7-9 While a few reports of medetomidine-ketamine in procyonids are published,² minimal to no data is documented regarding the success of medetomidine-ketamine-butorphanol in procyonids or, Nasua spp. more specifically. This report details the preliminary results of medetomidine-ketamine-butorphanol (MKB) at three separate zoological institutions (with and without additional isoflurane supplementation) to facilitate common medical and surgical procedures in captive, white-nosed coatis (Nasua narica).

Methods

Thirteen anesthetic events were performed in four adult white-nosed coatis (one male, three females), weighing 3–13 kg, using 57.3±6.5 µg/kg medetomidine (Domitor®, Pfizer Animal Health, Exton, PA 19341, USA), 5.6±2.1 mg/kg ketamine (Ketaset®, Fort Dodge Laboratories, Inc., Fort Dodge, IA 50501, USA), and 0.35±0.1 mg/kg butorphanol (Torbugesic®, Fort Dodge Laboratories, Inc.) combined and administered IM by a 3 ml pressurized plastic blowdart (Telinject USA, Inc., Saugus, CA 91350, USA) with a 1.1×30 mm needle or hand injected via syringe. Ten of these events were supplemented with isoflurane (IsoFlo®, Abbott Laboratories, North Chicago, IL 60064, USA) at a range of 0.5–2.5% of oxygen flow (average 1–2 L/min) for maintenance. In five events, inhalant anesthesia was maintained via endotracheal tube. In the other five events, isoflurane was provided via facemask. No additional injectable drugs were required to alter the anesthetic plane for the types of procedures performed once the animal became recumbent in all events.

Heart rate, respiratory rate, rectal temperature, and pulse oximetry data were collected throughout each procedure and recorded at 5-min intervals. Monitoring data and physiologic values for the injectable combination alone and the injectable combination plus isoflurane are summarized (Table 1). Procedures performed with the aid of these anesthetic combinations included physical examination, phlebotomy, vaccinations, radiography, abdominal ultrasonography, manual bladder expression for urine collection, dynamic endocrine testing, skin biopsy, wound lavage and bandage change, mass removal, and ovariohysterectomy. The injectable protocol alone was only used for physical examination, phlebotomy, and skin biopsy.

All anesthetic events were reversed with atipamezole (Antisedan®, Pfizer Animal Health). Eleven anesthetic events were reversed with 0.26±0.1 mg/kg atipamezole IM while in the remaining two events, atipamezole was administered half SC and half IM. In three events, naltrexone (Trexonil®, Wildlife Pharmaceuticals, Inc. Fort Collins, CO 80524, USA) reversed the butorphanol component at 10 mg/1 mg of butorphanol, with half administered SC and half IM. Complete recovery occurred in all anesthetic episodes.

Table 1

Physiologic monitoring data for medetomidine-ketamine-butorphanol with isoflurane (MKB + isoflurane) and medetomidine-ketamine-butorphanol alone (MKB). Data is reported as the mean ± standard deviation with ranges of measurements listed in the following row.

Results and Discussion

Mean time to first effect and mean time to recumbency for all anesthetic events was 3.5±1.6 min and 5.8±3.2 min, respectively. Mean time from darting to intubation in the events using supplemental inhalation anesthesia via endotracheal tube was 23.3±8.1 min. Total length of procedure was considered as the time from the initial darting to a return to sternal recumbency. Average length of procedure for the MKB plus isoflurane events was 148.3±82.4 min (range 66–325 min) while the average length of MKB events alone was 51.7±19.3 min (range 30–67 min). The mean time to arousal was 8.5±4.5 min (range 1–14 min) in the MKB plus isoflurane events and 5.4±4.0 min (range 1–9 min) in the MKB events. Times from administration of reversal agents to sternal recumbency were variable in the MKB plus isoflurane events at 35.5±33.2 with several taking over 50 min. Removal of one outlier event, involving a very prolonged recovery following isoflurane maintenance (>110 min from first arousal to sternal), provided a mean time from reversal to sternal recumbency of 25.9±13.8 min. In the MKB events, the mean time from reversal to sternal recumbency was 10.7±8.0 min.

Undesirable neuromuscular activity was observed in one MKB sedation. In this event, the animal began spasmodic jerking at 10 min post-injection followed by a 20 sec seizure at 40 min that necessitated reversal with atipamezole and naltrexone. No seizures were noted post reversal. Myoclonic activity was noted in two other MKB plus isoflurane events. One episode of bradycardia was observed in an MKB plus isoflurane event.

No seizures were reported when using MKB with supplemental isoflurane; however, increased visible neuromuscular activity was observed. Intermittent muscular twitching is an occasional reported effect of medetomidine used alone in domestic dogs.¹⁰ The paroxysmal neuromuscular twitching observed in two isoflurane-supplemented cases was attributed to this type of effect.

This is the first report of seizures with MKB in a non-domestic species. Addition or substitution of a benzodiazepine into the protocol may provide more consistent, safe use for injectable use alone. Overall, medetomidine-ketamine-butorphanol with supplemental isoflurane was effective for anesthesia; however, recovery times were considered prolonged in 30% of the events. More experience with this protocol in coatis is necessary to assess the anesthetic effects relative to previous ketamine and tiletamine-zolezepam anesthesias in these species. Preliminary results of medetomidine-ketamine-butorphanol without isoflurane show variable success, but do not support its use alone for longer procedures (>45–60 min) in this species due to the potential for seizure activity.

Acknowledgments

The authors would like to thank Drs. Julio Mercado, Tom Curro, and Doug Armstrong (Omaha Henry Doorly Zoo) and Dr. Nancy Lung (Fort Worth Zoo) for their support and help with this project. We thank the respective veterinary and animal care personnel at all of the institutions for their help with data collection. We would also like to thank Dr. Barbara Wolfe (North Carolina Zoological Park) for the sharing of anesthesia records.

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