Abstract
Euthanasia of stranded large whales poses substantial logistical, safety, pharmaceutical, delivery, public relations, and disposal challenges. Reasonable arguments can be made for allowing a stranded whale to expire naturally. However, slow gravitational suffocation, often combined with severely debilitating conditions, typically motivate humane efforts to end the animal's suffering. The size of the animal and prevailing environmental conditions can pose serious safety concerns for stranding personnel, which must take priority over other considerations. The size of the animal also necessitates large quantities of euthanasia agents. Drug residues are a concern for relay toxicity to scavengers, particularly with pentobarbital-containing euthanasia solutions.1 Pentobarbital can also be an environmental concern because of its stability and long persistence in aquatic environments.5 Appropriate ballistics may be used by trained individuals to avoid drug residues, but are not recommended for mysticetes other than minke whales.3 A technique using shaped explosive charges has been refined to an effective degree in Australia.2 This method requires a high level of training, and public acceptance in the United States seems unlikely in the near term. Here we describe a euthanasia technique for stranded mysticetes using readily available, inexpensive, preanesthetic and anesthetic drugs followed by saturated KCl, resulting in minimal drug residues of concern for relay toxicity, and no pentobarbital.
An 878 cm juvenile male humpback whale (Megaptera novaeangliae) estimated4 to weigh 9500 kg stranded in Hatteras Inlet, North Carolina. Midazolam (0.04 mg/kg IM, left cranial epaxials with a custom-made 16 ga 33 cm needle), acepromazine (0.2 mg/kg intrathoracic with 18 ga 55 cm needle) and xylazine (3.4 mg/kg IV, right pectoral fin with 18 ga 8.9 cm needle) administered over the course of 60 min rendered the whale minimally responsive. Saturated KCl (3 L of approximately 300 mg/ml or 4 mmol/ml solution; 100 mg/kg or 1.3 mmol/kg;) was administered intracardially (or IV near the heart) from a commercial garden sprayer pressurized reservoir via a 103 cm long 7 mm inner diameter 9.5 mm outer diameter needle, and the animal expired 7 min later. Plasma concentrations of midazolam, acepromazine and xylazine supported clinical assessment of adequate sedation and analgesia prior to KCl administration. Variations on this protocol have been successful with an additional humpback whale and a minke whale. Tissue drug concentrations indicate negligible risk to scavengers from midazolam and acepromazine even at injection sites, low risk for transient effects from xylazine concentration in liver, and potential risk for sedative effects from xylazine concentration at IM injection sites.
The midazolam, acepromazine, xylazine, saturated KCl technique resulted in acceptable euthanasia of mysticetes, with minimal risk of relay toxicity (although safe disposal of xylazine IM injection sites would be prudent), at relatively low cost. Midazolam is the only controlled drug in the protocol, and could likely be omitted when controlled drugs are not available. Every large whale stranding event poses unique challenges. Depending on a myriad of variables, this protocol may be appropriate in some circumstances.
Acknowledgements
Eric Anderson, Michele Bogardus, Heather Broadhurst, Karen Clark, Ari Friedlander, Gretchen Lovewell, Ray Mroch, Ann Pabst, Keith Rittmaster, Betsy Stringer, Joshua Summer, and personnel from Cape Lookout and Cape Hatteras National Seashores and the US Coast Guard all provided invaluable assistance.
References
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