Premortem diagnosis of a pancreatic neuroendocrine tumour (glucagonoma) in a captive North American river otter (Lontra canadensis)

A captive 10-year-old male North American river otter (Lontra canadensis) was evaluated for a 2-week history of weight loss and intermittent vomiting and regurgitation. Exploratory surgery identified a raised nodule on the quadrate lobe of the liver and an irregular nodule in the left limb of the pancreas. Partial lobectomy of the quadrate and right medial hepatic lobes was performed to excise the masses, and the pancreatic nodule was removed. Histological and immunohistochemical results were consistent with a glucagonoma that had metastasized to the liver. The otter received palliative care until 42 days postoperatively when it was humanely euthanized due to recurrence of clinical signs. Glucagonoma is a rare neoplasm in all species, with only a few cases reported in dogs, cats and horses. To the authors’ knowledge there are no other reports of glucagonoma in mustelid species.