CASE DESCRIPTION A 6-year-old castrated male Australian Shepherd was evaluated because of a recent onset of persistent hypoglycemia. CLINICAL FINDINGS Physical examination results were generally unremarkable. No abnormalities were detected on thoracic radiographs, and abdominal ultrasonography revealed no obvious pancreatic lesion. Hematologic analysis revealed hypoglycemia with a high serum insulin-to-glucose concentration ratio. TREATMENT AND OUTCOME Insulinoma was suspected; medical treatment with prednisone was initiated, and exploratory laparotomy was performed. No pancreatic lesions or masses were observed. Partial left pancreatectomy and hepatic and local lymph node biopsies were performed. Histologic examination revealed islet cell hypertrophy and hyperplasia, with no evidence of neoplasia. Results of a PCR assay of the pancreatic tissue for Bartonella infection were negative. Clinical, biochemical, and histopathologic findings were compatible with nesidioblastosis. The clinical signs, including hypoglycemia, resolved after surgery. On follow-up examination 8 months later, the dog was apparently healthy and results of a CBC and serum biochemical analysis, including blood glucose concentration, were within respective reference ranges. CLINICAL RELEVANCE To our knowledge, this is the first report of nesidioblastosis in a dog for which clinical signs and clinicopathologic abnormalities resolved after partial pancreatectomy. Although extremely rare, nesidioblastosis should be considered a differential diagnosis in dogs with signs suggestive of insulinoma.
