Pinniped Electroencephalography: Methodology and Findings in California sea lions
- Domoic acid
- Epilepsy
- Diagnostics
Abstract
This study was designed to identify abnormalities in the electroencephalograms (EEGs) recorded from stranded California sea lions (Zalophus californianus) with suspected domoic acid (DA) toxicosis. Recordings from animals presenting for non-neurological issues were also obtained to better understand the normal EEG (background activity and transient events) in this species, as, to date, studies have focused on examining natural sleep in pinnipeds. Most animals were sedated for electrode placement and EEG acquisition with some receiving antiepileptic medications or isoflurane during the procedure. A total of 103 recordings were read and scored from 0 (normal) to 3 (severely abnormal). Epileptiform discharges, consisting of spikes, sharp waves, slow waves, and/or spike waves, were present in all EEGs with scores of 1, 2, or 3. The distribution of these events over the scalp varied. While often generalized, others were lateralized over one hemisphere, bifrontal, bioccipital, and/or bitemporal, while some discharges were multifocal. Findings were different between sea lions and occasionally changed within the EEG on a given sea lion. No clinical seizures were observed during the recording but a few sea lions had findings consistent with electroencephalographic seizures. When available, supporting diagnostic results obtained from magnetic resonance imaging (MRI) and/or necropsy/histopathology were described, as well as the status of those sea lions that recovered and were released with satellite tags.
Williams, D.C., Haulena, M., Dennison, S., Waugh, L., Goldstein, T., Nutter, F., Van Bonn, B., Hoard, V., Laxer, K.D., Buckmaster, P.S. and Gulland, F.M., 2023. Pinniped electroencephalography: Methodology and findings in California sea lions (Zalophus californianus). Frontiers in Veterinary Science, 10.
Related Publications
{"image":"\/Animals\/Patients\/California sea lions\/csl-by-bill-hunnewell-c-the-marine-mammal-center-1.jpg","alt":"California sea lion eating a fish","title":"New Technique for Diagnosing Lung Parasite Infections in Sea Lions","link_url":"https:\/\/www.marinemammalcenter.org\/publications\/new-technique-for-diagnosing-lung-parasite-infections-in-sea-lions","label":"Research Paper"}
{"image":"\/Animals\/Patients\/Elephant seals\/cropped-images\/es-by-bill-hunnewell-c-the-marine-mammal-center-3-2-1214-3454-3512-1600891002.jpg","alt":"northern elephant seal","title":"Diagnostic Tests for Lungworm-Infected Northern Elephant Seals","link_url":"https:\/\/www.marinemammalcenter.org\/publications\/diagnostic-tests-for-lungworm-infected-northern-elephant-seals","label":"Research Paper"}
{"image":"\/People\/Action\/Veterinary care\/cropped-images\/cara-field-fur-seal-exam-by-bill-hunnewell-c-the-marine-mammal-center-0-0-1245-1000-1601838274.jpg","alt":"Dr. Cara Field takes blood from a fur seal","title":"Evaluating Diagnostic Tools for White Blood Cell Counts in Pinnipeds","link_url":"https:\/\/www.marinemammalcenter.org\/publications\/evaluating-diagnostic-tools-for-white-blood-cell-counts-in-pinnipeds","label":"Research Paper"}
{"image":"\/Animals\/Wild\/Other species\/cropped-images\/fin-whale-fort-funston-by-barbie-halaska-c-the-marine-mammal-center-259-328-3782-2954-1619455378.jpg","alt":"","title":"Analyzing Stress and Reproductive Steroid Hormones in Gray and Fin Whales","link_url":"https:\/\/www.marinemammalcenter.org\/publications\/analyzing-stress-and-reproductive-steroid-hormones-in-gray-and-fin-whales","label":"Research Paper"}
Recent News
{"image":"\/Animals\/Wild\/Elephant seal\/cropped-images\/wild-es-ano-nuevo-photo-by-clive-beavis-159-0-1270-992-1772151576.jpg","alt":"wild northern elephant seal at ano nuevo state park","title":"Avian Influenza Confirmed in Northern Elephant Seals","link_url":"https:\/\/www.marinemammalcenter.org\/news\/avian-influenza-confirmed-in-northern-elephant-seals","label":"News Update","date":"2026-02-26 01:00:00"}
{"image":"\/Animals\/Wild\/Gray whale\/cropped-images\/two-gray-whales-golden-gate-bridge-shutterstock-0-0-1270-992-1770234810.jpg","alt":"two gray whales under the Golden Gate Bridge","title":"The Marine Mammal Center and San Francisco Harbor Safety Committee Pilot New Vessel Operator Training Program","link_url":"https:\/\/www.marinemammalcenter.org\/news\/the-marine-mammal-center-and-san-francisco-harbor-safety-committee-pilot-new-vessel-operator-training-program","label":"Press Release","date":"2026-02-06 01:00:00"}
The Marine Mammal Center and San Francisco Harbor Safety Committee Pilot New Vessel Operator Training Program
February 6, 2026
Read More{"image":"\/Animals\/Wild\/Bottlenose dolphin\/cropped-images\/dolphinphoto-by-adam-li-c-noaa-0-0-1270-992-1769539954.jpg","alt":"A bottlenose dolphin jumps out of the water.","title":"What\u2019s the Difference Between Dolphins and Porpoises? And Other Animal Trivia","link_url":"https:\/\/www.marinemammalcenter.org\/news\/whats-the-difference-between-dolphins-and-porpoises-and-other-animal-trivia","label":"News Update","date":"2026-01-26 23:00:00"}
What’s the Difference Between Dolphins and Porpoises? And Other Animal Trivia
January 26, 2026
Read More{"image":"\/Animals\/Patients\/Sea otters\/2025\/cropped-images\/so-mooring-release-2-laurie-miller-c-the-marine-mammal-center-USFWS-permit-MA101713-1-147-8-1270-992-1770307740.jpg","alt":"Sea otter - Mooring","title":"Rescue Stories: Southern Sea Otter Mooring Named the 2025 Patient of the Year","link_url":"https:\/\/www.marinemammalcenter.org\/news\/rescue-stories-vote-for-your-favorite-marine-mammal-patient-of-2025","label":"News Update","date":"2026-01-16 10:05:08"}
Rescue Stories: Southern Sea Otter Mooring Named the 2025 Patient of the Year
January 16, 2026
Read More