Gastrinoma and Zollinger-Ellison syndrome in canids: a literature review and a case in a Mexican gray wolf

Abstract

Gastrinoma, an infrequent diagnosis in middle-aged dogs, occurs with nonspecific gastrointestinal morbidity. Laboratory tests can yield a presumptive diagnosis, but definitive diagnosis depends on histopathology and immunohistochemistry. We describe a malignant pancreatic gastrinoma with lymph node metastases and corresponding Zollinger-Ellison syndrome in a Mexican gray wolf ( Canis lupus baileyi) and review this endocrine neoplasm in domestic dogs. A 12-y-old, captive, male Mexican gray wolf developed inappetence and weight loss. Abdominal ultrasonography revealed a thickened duodenum and peritoneal effusion. Two duodenal perforations were noted on exploratory celiotomy and were repaired. Persisting clinical signs led to a second celiotomy that revealed a mesenteric mass, which was diagnosed histologically as a neuroendocrine carcinoma. During the following 16 mo, the wolf received a combination of H₂-receptor antagonists, proton-pump inhibitors, gastroprotectants, and anti-emetics, but had recurrent episodes of anorexia, nausea, acid reflux, and remained underweight. Worsening clinical signs and weakness prompted euthanasia. The antemortem serum gastrin concentration of 414 ng/L (reference interval: 10-40 ng/L) corroborated hypergastrinemia. Autopsy revealed a mass expanding the right pancreatic limb; 3 parapancreatic mesenteric masses; duodenal ulcers; focal duodenal perforation with septic fibrinosuppurative peritonitis; chronic-active ulcerative esophagitis; and poor body condition. The pancreatic mass was diagnosed histologically as a neuroendocrine carcinoma and the parapancreatic masses as lymph node metastases. Immunohistochemistry of the pancreatic mass was positive for gastrin and negative for glucagon, insulin, pancreatic polypeptide, serotonin, somatostatin, and vasoactive intestinal peptide.

Keywords: Canis lupus baileyi; Mexican gray wolf; Zollinger–Ellison syndrome; dogs; gastrin; gastrinoma; neuroendocrine tumor; ulcer.

Figures 1–4.

Pancreatic gastrinoma and Zollinger–Ellison syndrome in a Mexican gray wolf (Canis lupus baileyi). Figure 1. Focally expanding the right pancreatic limb and abutting the duodenum is a gastrinoma (*). In the adjacent mesentery, there are 2 lymph node metastases (x). There is a focal perforating ulcer (arrow) with bile-stained adipose tissue located 13 cm distal to the pylorus on the duodenal antimesenteric border. Inset: cross-section of the pancreatic gastrinoma. Figure 2. The gastric pylorus has an undulating mucosa thickened by mucus cell hyperplasia and hypertrophy and with scattered lymphocytes in the lamina propria. H&E. Figure 3. Neoplastic cells that infiltrate the pancreas are arranged in packets typical of a neuroendocrine carcinoma. H&E. Figure 4. Neoplastic cells that infiltrate the pancreas have strong cytoplasmic staining for gastrin. Gastrin immunohistochemistry, DAB chromogen, hematoxylin counterstain.