Abstract

The Pacific Marine Mammal Center (PMMC) rescues, rehabilitates, and releases marine mammals that strand sick or injured in Orange County, California. The majority of patients are young pinnipeds (California sea lions, Pacific harbor seals, and Northern elephant seals under two years of age) that are severely malnourished, dehydrated, and hypothermic with secondary ailments including hypoglycemia, pneumonia, abscesses, trauma, sepsis, and gastrointestinal foreign bodies. Priority on intake is triage and stabilization; therefore, patient handling should be limited in these unstable patients.

To minimize stress, survey radiographs are performed while the patient is contained in a plastic transport kennel immediately upon admission. Priority is placed on whole-body imaging without significant concern for positioning in initial survey radiographs. Despite non-diagnostic positioning, this low-stress method of obtaining radiographs allows preliminary evaluation for common presentations seen in immature wild pinniped.¹

A large number of intake radiographic findings have helped direct therapeutic plans or indicated the need for more appropriately positioned radiographs under manual restraint or general anesthesia following stabilization. Examples of significant findings on survey radiographs included a patient with more than 40 rocks in the gastric lumen, a fishing hook in the cervical musculature adjacent to the esophagus, various fractures, osteomyelitis, pneumonia, pneumothorax, ileus, and subcutaneous emphysema associated with abscesses. Early identification of some problems is invaluable in guiding medication plans and pain management, and also highlights precautions necessary during manual restraint and tube feeding if a patient has fractures or gastric foreign bodies.

For pinnipeds that strand deceased, postmortem radiographs aid in determining the cause of death, help direct necropsy examination, and increase the ability to identify human interactions such as gunshots and fishing gear.² Since the implementation of radiographs in postmortem investigation, detection of metallic foreign bodies (airsoft pellets, various types of bullets, buckshot, and fishing hooks), has significantly increased. These findings help inform management and policymakers of a more accurate prevalence of these human interaction concerns and aid in conservation efforts, community education, and outreach.

Overall, the application of survey radiographs has improved patient care, research efforts, and detection of human interactions. While the positioning is not always ideal, survey radiographs have proven invaluable when establishing treatment plans for rehabilitating pinniped patients and assessing causes of mortality in postmortem examinations.

Acknowledgements

The authors wish to thank the staff and volunteers at the Pacific Marine Mammal Center. The authors would also like to thank the Massen Greene Foundation and the McBeth Foundation for their generous donations towards PMMC’s rescue and research efforts. Rescue, rehabilitation, and necropsy activities were conducted under the NOAA stranding agreement.

*Presenting author

Literature Cited

1.  Dennison SE, Forrest L, Gulland FMD. Normal thoracic radiographic anatomy of immature California sea lions (Zalophus californianus) and immature northern elephant seals (Mirounga angustirostris). Aquat Mamm. 2009;35:36–42.

2.  Goldstein T, Johnson SP, Phillips AV, Hanni1 KD, Fauquier DA, Gulland FMD. Human-related injuries observed in live stranded pinnipeds along the central California coast 1986–1998. Aquat Mamm. 1999;25:43–51.