Risk Factors Associated with Perianesthetic Mortality of Rehabilitating California Sea Lions (Zalophus californianus)
The objective of this retrospective case-control study was to identify risk factors that may predispose rehabilitating California sea lions (Zalophus californianus) to perianesthetic mortality. Hospital records of 281 California sea lions that underwent sedation or general anesthesia while at a rehabilitation center in California from 2004 through 2008 were reviewed, including records from 419 anesthetic events. All California sea lions that died (n=15) during or in the subsequent 72 hours of anesthesia, were classified as cases. All sea lions that survived (n=404) were classified as controls. The following risk factors for anesthetic death were reviewed: gender, age class, health status, duration of anesthetic period, atropine premedication, induction protocols, and maintenance protocols.
The prevalence of mortality during anesthesia was 3.1% (n=13) over the five-year period. With the inclusion of animals that died within 72 hours post anesthesia, the total mortality prevalence rose to 3.6% (n=15). The only factor associated with increased odds of anesthetic-related death was premedication with atropine, whereas good health status was protective and associated with reduced odds. The most common time of death was during anesthetic maintenance. Results suggest that the use of atropine as a premedication should be avoided. Understanding risk factors associated with anesthetic-related deaths in pinnipeds will help veterinarians identify high-risk patients and improve patient care during anesthesia.