Our experience during the EVOS demonstrated the value of performing macroscopic and microscopic examinations on oiled sea otters that died. It also indicated the importance of baseline measurements for wildlife before an oil spill. Detailed postmortem examinations, histopathologic assessment, and blood chemistries provide the most valuable information for veterinarians caring for sea otters in the rehabilitation centers. Conversely, toxicological tests are comparatively expensive, time consuming, and often yield ambiguous results.
Major factors contributing to the mortality of oiled sea otters appear to be: 1) hypothermia, 2) shock and secondary organ dysfunction, 3) interstitial emphysema, 4) gastrointestinal ulceration, and 5) stress during captivity. Direct oil toxicosis may be a contributing factor, but is difficult to verify in otters contaminated during an oil spill.
