A 19-year-old male sea otter (Enhydra lutris) exhibited systemic seizures, declining consciousness, temporary cardiopulmonary arrest, and right-side rotation. The sea otter died approximately one month after its initial seizure. Postmortem magnetic resonance imaging examination revealed a high-intensity region in the left frontal lobe. At necropsy, a gelatinous lesion in the left frontal lobe of the brain was revealed. Histopathologically, the lesion consisted of neoplastic proliferation of round to polyhedral monomorphic cells with a honeycomb growth pattern, small round nuclei, and cytoplasmic halos. The neoplastic cells were immunopositive for oligodendrocyte transcriptional factor-2 (OLIG2) and immunonegative for glial fibrillary acidic protein (GFAP). In this study, we describe the clinical signs and histopathological features of oligodendroglioma, which have rarely been reported in sea otters.
Kezuka et al. (Thu,) studied this question.