Abstract
Elasmobranchs are common, iconic species in aquaria, and their wild counterparts are often key members of their ecosystem.1 Both wild and managed elasmobranchs are particularly prone to infectious meningoencephalitis.2-6 Common pathogens in stranded elasmobranchs include Carnobacterium maltaromaticum and Miamiensis avidus, though other infectious agents have been reported in elasmobranchs under managed care.2-8 Potential routes of entry include the endolymphatic ducts, olfactory system, ampullary system, and hematogenous spread, but published literature commonly does not definitively identify a specific route of entry.2,5,6,8,9
Postmortem examination is a critical tool for disease monitoring of wild, stranded elasmobranchs and management of those under human care. Careful necropsy of the head with a focus on clinically relevant anatomy can ensure proper samples are collected, may increase the chance of presumptive diagnoses prior to histologic analysis, which can allow for faster management decisions, and can often identify the route of pathogenesis, which is a current shortcoming in the published literature.2,5,8-10
This protocol emphasizes careful dissection of the endolymphatic pores/ducts, inner ear, and olfactory system and provides methods for gross necropsy, sample collection for microbiology, cytology, and histopathology, and evaluation of wet-mount and stained cytology. The proposed protocol for the elasmobranch head necropsy and ancillary diagnostic sample collection and evaluation was developed through work with stranded, wild elasmobranchs and has been implemented in the necropsy of over 150 elasmobranchs across 16 species from 2011–2023, including both wild, stranded elasmobranchs and those under human care.
Acknowledgments
We gratefully acknowledge all the organizations and individuals who have helped with stranded elasmobranch response, including notification, collection, and providing necropsy space, particularly the University of California, Davis School of Veterinary Medicine, California Department of Fish and Wildlife, and Monterey Bay Aquarium.
*Presenting author
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