Perioperative Glycemic Changes Following Partial Pancreatectomy for a Pancreatic Islet Cell Neoplasm in a Dog: A Case Report

Canine insulinomas are functional pancreatic neuroendocrine tumors that typically cause hypoglycemia, but blood glucose may fluctuate before surgery and increase after resection. This report describes the diagnostic evaluation, surgical treatment, and perioperative glycemic course of a 12-year-old female Miniature Schnauzer with a pancreatic islet cell neoplasm considered clinically consistent with insulinoma. Intermittent low or low-normal blood glucose concentrations ranging from 54 to 72 mg/dL were documented before surgery, and the blood glucose concentration on the day of surgery was 73 mg/dL. Contrast-enhanced computed tomography identified a mass in the left pancreatic limb, and partial pancreatectomy was subsequently performed. Blood glucose reached 416 mg/dL 2 h after pancreatic mass removal while surgery was ongoing, then initially declined without insulin administration. Recurrent postoperative hyperglycemia was treated with regular insulin on postoperative days (PODs) 2 and 3, whereas subsequent decreases in blood glucose were treated with dextrose supplementation. Blood glucose continued to fluctuate on POD 4; no additional insulin was administered after POD 3. Histopathologic examination identified a pancreatic islet cell neoplasm. Although a paired serum insulin concentration during documented hypoglycemia was not available and immunohistochemical staining for insulin or other neuroendocrine markers was not performed, the clinical, imaging, glycemic, and histopathological findings were considered consistent with a clinicopathologic diagnosis of insulinoma. Blood glucose was 150 mg/dL on POD 7; subsequent recorded concentrations through POD 150 ranged from 107 to 133 mg/dL. Serial glucose monitoring helped characterize the perioperative course and guide postoperative insulin and dextrose treatment.