Abstract
Unique physiologic adaptations that facilitate diving in marine mammals are suspected to contribute to higher perianesthetic mortality compared to terrestrial mammals.1,3,5-8,10,12-16 Perianesthetic mortality rates in dogs and cats have been reported as 0.11–1.5% and 0.06–1.08%, respectively,2,4,9,11 while one study reported a perianesthetic mortality rate of 4.3% in stranded California sea lions.12 However, no case-control study exists for phocids. The objective of this study is to identify perianesthetic mortality risk factors in stranded northern elephant seals (Mirounga angustirostris; NES) and Pacific harbor seals (Phoca vitulina richardsi; PHS) undergoing rehabilitation. Medical records of anesthetized NES and PHS patients from The Marine Mammal Center (Sausalito, CA) between 2018–2023 were reviewed, and 333 anesthetic events identified. Mortality events during or within 72 hours after anesthesia were classified as cases (n=9). Events through which the patient survived were classified as controls (n=283). Animals euthanized during anesthesia for reasons unrelated to anesthetic complications were excluded from analysis (n=41). Risk factors reviewed included species, sex, age class, body weight, ASA status, duration of anesthetic event, induction protocols, maintenance protocols, intubation, mechanical ventilation, and history of prior anesthesia. Mortalities related to anesthetic events represented 3.1% (n=9). The most common time of death was during the initial 3 hours of recovery. Initial analysis shows PHS have a greater risk of perianesthetic mortality than NES (p=0.04). No other significant risk factors specifically associated with perianesthetic mortality were identified; however, review of medical records prior to 2018 is ongoing.
*Presenting author
+Student presenter
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