Canine Gastrinoma with Long-Term Survival After Primary and Repeat Surgeries Using Serial Serum Gastrin Concentrations as an Adjunctive Monitoring Marker: A Report of Two Cases

Gastrinoma is a rare neuroendocrine tumor in dogs that arises from functional pancreatic non-β cells and secretes excessive gastrin. Gastrinoma in dogs has a high metastasis rate at diagnosis, and curative treatment is often difficult. There are few reports describing the long-term outcomes of surgical treatment in dogs with gastrinoma, and no established method for monitoring disease progression has been reported. We report here the cases of two adult dogs with pancreatic gastrinoma treated with surgical resection. Pharmacological therapy using proton pump inhibitors was administered to control gastrointestinal symptoms caused by hypergastrinemia. Multiple surgeries were performed to reduce the volume of primary and metastatic gastrinoma lesions. Serial serum gastrin concentrations were used as an adjunctive monitoring marker during follow-up. Changes in serum gastrin concentrations were used to support decisions regarding further imaging. Additional surgery was performed based on serum gastrin concentrations, clinical signs, and diagnostic imaging findings. A total of four surgeries were performed in Case 1 and three surgeries in Case 2. Both dogs maintained well-controlled gastrointestinal symptoms and showed long-term survival. The changes in serum gastrin concentrations in these cases suggest that serial serum gastrin measurement may be useful for monitoring recurrence or tumor progression in canine gastrinoma.