Abstract

Harbor seals (Phoca vitulina) are a common species admitted to marine mammal rehabilitation facilities. As sentinels of ocean health, monitoring trends in harbor seal populations is critical. Few studies have evaluated neurologic disease in harbor seals; therefore, advancing knowledge is vital to identification of emerging diseases of concern and for providing insight into coastal ecosystem health.^1-6 The purpose of this study was to identify and characterize neurologic disease in free-ranging stranded Atlantic harbor seals. A retrospective review of medical records from Mystic Aquarium’s Animal Rescue Program from 2006 to 2019 was conducted. Inclusion criteria included any Atlantic harbor seal that stranded alive during the study period and was diagnosed with neurologic disease. In total, 211 records were reviewed, and 24 animals met the inclusion criteria. Prevalence of neurologic disease was 11% in the study population and six major categories of neurologic disease were identified including: inflammatory (5.6%), idiopathic (3.3%), trauma (1.8%), congenital (<1%), degenerative (<1%), and vascular (<1%). There were no cases of neurologic disease associated with neoplasia. Of the seals diagnosed with neurologic disease, 13 seals (54%) died during rehabilitation, 10 seals (42%) were euthanized, and one seal (4%) survived to release. One unique degenerative lesion identified, neuroaxonal dystrophy, has not been previously reported in marine mammals. This study’s results contribute to the overall knowledge of the health of free-ranging Atlantic harbor seals and aid clinicians in characterization of neurologic conditions that may be present in free-ranging Atlantic harbor seals undergoing rehabilitation.

Acknowledgements

The authors thank Janelle Schuh for her contributions to this study and the volunteers and staff of Mystic Aquarium’s Animal Rescue Program for their efforts in harbor seal rehabilitation and conservation.

*Presenting author
⁺Student presenter

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