CASE REPORT SEDATION AND LOCAL ANESTHESIA AS AN ALTERNATIVE TO GENERAL ANESTHESIA IN 3 BIRDS

Amber Lee, BVSc, and Angela Lennox, DVM, Dip. ABVP (Avian, Exotic Companion Mammal), Dip. ECZM (Small Mammal)

Sedation combined with local anesthesia can provide a safe alternative to general anesthesia or simple manual restraint for a variety of minor surgical procedures in captive birds. The following case reports demonstrate the use and safety of midazolam and butorphanol, along with local lidocaine and bupivacaine for various procedures including mass removal and digit amputation. In each case, sedation allowed restraint with minimal patient stress with the local block appearing to provide adequate analgesia. Each patient experienced an uneventful recovery. Copyright 2016 Elsevier Inc. All rights reserved.

Key words: sedation; local anesthesia; midazolam; lidocaine; psittacine; poultry

edation is commonly used in human and veterinary medicine for a variety of diagnostic and therapeutic procedures. In avian medicine, either manual restraint alone or general anesthesia with inhalant agents has been advocated for sample collection, diagnostic imaging, and other medical procedures.1 Studies suggest that manual restraint of birds induces a stress response, as demonstrated by an increase in body temperature, respiratory rate, and plasma corticosteroneS levels.2-7 Stress is of particular concern for sick avian patients who could quickly decompensate upon handling. Unnecessary staff exposure to anesthetic gas should be avoided whenever possible. In theory, handling and restraint techniques that minimize physiologic responses to stress and avoid the risk inherent with general anesthesia should provide a better outcome and encourage a less negative relationship between the avian patient and veterinarian.

Sedation in birds has been recently described for IL USA) and butorphanol (butorphanol tartrate, a variety of procedures, including restraint for 10 mg/mL; Dolorex, Intervet, Millboro, DE USA).1,8 physical examination, venipuncture, vascular Midazolam is the most commonly used drug for access, and for diagnostic imaging.1,8 Drugs used sedation in humans.11 Midazolam is short acting, for sedation have also been used as can be administered through a variety of routes, and premedications for general anesthesia.9,10 With the is preferred over the longer-acting diazepam and addition of a local anesthetic agent, sedation can lorazepam.11,12 The effects of midazolam can be be expanded to include slightly to moderately antagonized by flumazenil (flumazenil painful procedures, such as wound care, placement hydrochloride; Abaxis Pharmaceutic Products, of an intraosseous catheter, and digit amputation.8 Schaumberg, IL USA).1,12 This represents a useful alternative to general A few recently published studies examined the anesthesia, especially for compromised patients. effects of intranasal midazolam alone in various Drugs used for sedation in birds include avian species, including Hispaniolan Amazon anxiolytic agents such as midazolam (midazolam parrots (Amazona ventralis).3 Others used hydrochloride, 5 mg/mL; Hospira Inc., Lake Forest, midazolam via various routes in finches and

From the Avian and Exotic Animal Clinic of Indianapolis, Indianapolis, IN USA. Address correspondence to: Amber Lee, BVSc, Avian and Exotic Animal Clinic of Indianapolis, 9330 Waldemar Road, Indianapolis, IN 46268. E-mail: [email protected] Ó 2016 Elsevier Inc. All rights reserved. 1557-5063/16/2101-$30.00 http://dx.doi.org/10.1053/j.jepm.2016.03.012

100 Journal of Exotic Pet Medicine 25 (2016), pp 100–105 canaries, in some cases with the addition of other than lidocaine in species for which pharmacokinetic drugs. In general, published dosage data are available. There have been mixed results in recommendations vary from 0.1 to 2 mg/kg, with studies with bupivacaine in mallard ducks, suggesting lower dosages advocated for the intravenous it may have high-plasma levels 6 to 12 hours after route.1,3,9,13 Benzodiazepines can be used in subcutaneous administration.21 However, another combination with butorphanol for sedation and for study showed limited efficacy or adverse effects.22 preanesthesia in birds.1,8,9 Butorphanol is a mixed More research is required to determine safe and agonist/antagonist with low activity at the efficacious dosages for bupivacaine in birds. µ receptor, but strong agonist activity at the k receptor. Several studies have demonstrated the CASE REPORTS efficacy of butorphanol for pain management in African gray parrots14 and Hispaniolan Amazon Case 1 15,16 parrots and suggest that a dosage range of 1 to A 17-year-old blue-crowned conure (Thectocercus 4 mg/kg intramuscularly or intravenously every acuticaudatus) presented for a small 2 to 3 mm 1 to 2 hours may provide adequate analgesia. smooth mass present between the commissures of Dosages suggested for midazolam and butorphanol the upper and lower beak on the left side of the face in combination for sedation and preanesthesia also (Fig. 1A). The mass had been present for 7 weeks vary and range from 0.1 to 2.0 mg/kg midazolam and the owner had delayed addressing the mass 1,18-10 and 1 to 3 mg/kg butorphanol. The author and because of personal reservations regarding stress, others have found that the addition of butorphanol discomfort, and general anesthesia in this older bird. allows lower effective dosages of midazolam; an The bird was otherwise normal on physical fi additional bene t is the provision of analgesia. examination, and a complete blood cell count was A study comparing the use of sedation vs. within reference ranges. A combination of general anesthesia for computed tomography midazolam (0.5 mg/kg) and butorphanol (3 mg/kg) used a combination of butorphanol at 0.86 to were administered together in a single syringe into 2.55 mg/kg intramuscularly and midazolam at the pectoralis muscle. Within 5 to 10 minutes, the 0.86 to 1.53 mg/kg intramuscularly; some birds bird was dorsally recumbent, but could be easily required additional dosages, but all underwent roused with handling or noxious stimuli (e.g., toe computed tomography that was found nearly pinch) (Fig. 1B). Monitoring was achieved through equal to the quality of images acquired under the use of an ultrasonic Doppler. Lidocaine (2 mg/ 10 general anesthesia. kg) and bupivacaine (2 mg/kg) were injected Local anesthetics work by blocking sodium around and beneath the mass (Fig. 1C). An incision channels in the nerve axon, which interferes with the was made over the mass, and a small amount of generation and conduction of action potentials debris removed, consistent with a cyst. The incision along a nerve. They provide preemptive analgesia by site was flushed and bleeding controlled with a reducing the number and frequency of nerve cotton-tipped applicator (Fig. 1D). Recovery was impulses and also reduce nociceptor receptivity. uneventful and the bird was able to stand within 30 Lidocaine (lignocaine hydrochloride, 20 mg/mL; minutes following the surgical procedure. The Sparhawk Laboratories, Inc., Lenexa, KS USA) has patient was discharged several hours later. been used for cutaneous anesthesia in some animal species,17 and anesthetic sparing effects have been Case 2 studied in birds.18 Ideal effective and safe dosages for birds are unknown. Anecdotal reports suggest A 2-year-old male cockatiel (Nymphicus hollandicus) that birds are more sensitive to local anesthetics. presented with a necrotic fourth digit of the left More recent studies in adult chickens where pelvic limb because of a constriction injury lidocaine was administered at 6 mg/kg (Fig. 2A). The rest of the physical examination was intravenously once under isoflurane anesthesia did normal with the exception of a slightly thin body not produce adverse cardiac effects.19 Lidocaine condition. The owner declined additional workup. buffered with sodium bicarbonate has been The bird was sedated with midazolam (0.5 mg/kg) advocated over lidocaine alone to neutralize the pH and butorphanol (3 mg/kg) that were and minimize patient discomfort.20 administered intramuscularly. Preoperative Bupivacaine (bupivacaine hydrochloride, subcutaneous fluids (4 mL) were administered. 5 mg/mL; Hospira Inc., Lake Forest, IL USA) is used Within 10 minutes, the patient was sternally less frequently in birds because of the concern of recumbent with monitoring of vital signs prolonged toxic effects, as the drug is longer acting conducted as described in Case 1. A lidocaine

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