Diagnosis and treatment of gastrinoma

Canine Gastric Pathology: A Review

Gastric disorders are common in dogs and are a major reason for veterinary consultation. In human medicine, the classification of gastric diseases based on histological features, genotypes and molecular phenotypes helps to better understand the characteristics of each subtype, and to improve early diagnosis, prevention and treatment. Canine gastric lesions often show strong histological similarities to their human counterparts. However, such conditions in the canine stomach are poorly studied and their cellular and molecular features are largely unknown. This article reviews the histopathological classification of inflammatory and neoplastic lesions of the canine stomach and provides an update on the application of molecular techniques within the field of canine gastric pathology. The canine disorders are compared with current knowledge of the equivalent human diseases.

Normal dogs treated with famotidine for 14 days have only transient increases in serum gastrin concentrations

BACKGROUND

In people, serum gastrin concentrations increase in response to administration of H(2) receptor antagonists, but the effect of famotidine administration on serum gastrin concentrations has not been evaluated in dogs.

OBJECTIVES

To determine if serum gastrin concentrations increase in response to 14 days of famotidine treatment and the time needed to return to baseline after discontinuation of famotidine; define stability of gastrin in samples held at room temperature.

ANIMALS

Eleven healthy dogs were included in part A (famotidine treatment) and 7 healthy dogs in Part B (serum gastrin stability). In part A, famotidine (0.5 mg/kg p.o. q12h) was administered for 14 days. Fasting blood samples were collected on days 0, 3, 7, 11, 14, 16, 18, 20, and 22. In part B, blood was collected after a 12-hour fast. Gastrin concentrations in serum samples held at room temperature for ≤30 minutes after sampling were compared to concentrations in samples held at room temperature for 150 minutes after sampling.

RESULTS

Serum gastrin concentrations increased by day 3 of famotidine administration and returned to baseline concentrations in all dogs by day 14 despite continued famotidine administration. Serum gastrin concentrations were lower (20% mean decrease; P = .0005) in samples held at room temperature for 150 minutes.

CONCLUSIONS AND CLINICAL IMPORTANCE

After 14 days of famotidine administration, clinically healthy dogs have normal serum gastrin concentrations. In a dog with clinical features consistent with gastrinoma, chronic famotidine administration is unlikely to contribute to increases in serum gastrin concentrations.

Canine gastrinoma: a case study and literature review of therapeutic options

CASE HISTORY

A 6.2 kg, 8-year-old, spayed female Australian Terrier was presented with weight loss, inappetence, lethargy and a 2-day history of intermittent vomiting.

CLINICAL FINDINGS

The dog had cranial abdominal pain and there was melaena present on digital rectal examination. Haematology revealed a marked, acute leucogram.

DIAGNOSIS AND TREATMENT

Fasting serum gastrin levels were markedly elevated and gastrinoma was suspected. Treatment was initiated with omeprazole, ranitidine and sucralfate. The dog remained clinically normal for 26 months, at which time exploratory surgery was undertaken and the dog subsequently euthanised due to extensive metastases. Histopathology and immunocytochemistry confirmed the diagnosis of metastatic gastrinoma.

CLINICAL RELEVANCE

This is a rare condition infrequently reported. Although the number of cases treated with omeprazole are too few to draw firm conclusions, it would appear that proton pump inhibitors are useful and should be considered for cases of gastrinoma managed medically. Long-term prognosis is poor, and survival times range from 1 to 147 weeks. Many treatment options are discussed in the medical literature though not all are feasible in veterinary patients.

Common bile duct obstruction due to a duodenal gastrinoma in a dog

In dogs gastrinomas are rare endocrine neoplasms that have always been reported to arise from the pancreas. We report here what we believe to be the first case of a duodenal gastrinoma in a dog. A nine-year-old, male, Pekinese dog was presented with a three-day history of anorexia, vomiting and mucous diarrhoea. Clinical examination and laboratory findings suggested the presence of a severe hepatobiliary disorder. Abdominal ultrasonography showed a diffuse increase in echogenicity of the liver, with severe gallbladder dilation and marked dilation of the cystic duct, common bile duct and extrahepatic bile ducts. Based on these findings, an extrahepatic biliary tract obstruction (EBTO) of unknown cause was suspected. At laparotomy, the gallbladder and the extrahepatic bile ducts appeared severely dilated. The gallbladder was tense and could not be compressed suggesting an outflow obstruction. The duodenum at the level of the common duct orifice appeared slightly thickened and severely hardened for a length of 1 cm. Biopsies from the duodenum and liver were obtained and a cholecystoduodenostomy was performed. The duodenal biopsy revealed severe fibrosis of the submucosa and a infiltrate of small pockets and cords of round to polygonal cells with granular cytoplasm. Based on this appearance the differential diagnoses included neuroendocrine tumours and poorly differentiated carcinoma. Despite surgery and supportive therapy the dog continued to be anorexic and to vomit 3-6 times daily. After euthanasia and necropsy, histopathology showed the presence of a neuroendocrine neoplasia involving the duodenal wall with focal invasion of the adjacent pancreas and small liver metastases. On immunohistochemistry, the cytoplasm of approximately 90% of neoplastic cells intensely expressed neuron specific enolase and gastrin. These findings were consistent with a diagnosis of gastrinoma.

Concurrent gastrinoma and somatostatinoma in a 10-year-old Portuguese water dog

Severe hypergastrinaemia in the dog is considered a strong indicator for a gastrin-producing pancreatic islet cell tumour. In human medicine, gastrinomas are described as enteropancreatic neuroendocrine tumours that cause the Zollinger-Ellison syndrome. However, in contrast to the supposed origin of canine gastrinomas in pancreatic islets, gastrinomas in human beings arise predominantly in the duodenum and gastric antrum, and are often a component of the syndrome of multiple endocrine neoplasia type I. This report is of a canine case of multiple endocrine neoplasms, consisting of a pancreatic islet cell somatostatinoma, and a gastrinoma in the mesenteric lymph nodes and liver. From the literature and the authors' findings, it is concluded that the clinical diagnosis of hypergastrinaemia is not pathognomonic for a gastrin-producing islet cell tumour. Furthermore, the presence of an islet cell tumour in the face of hypergastrinaemia does not warrant a diagnosis of an islet cell gastrinoma. Immunohistochemistry is necessary to confirm the diagnosis of a pancreatic islet cell gastrinoma.

A case of canine gastrinoma

The dog of this case was a 10-year-old Shih Tzu with refractory vomiting, diarrhea and anorexia. Endoscopy revealed an unclear at gastric angle, a stenosis at pyloric antrum and congestion in duodenal mucosa. Since abnormal shadows of irregular echo-levels were disclosed by pancreas ultrasonography, serum gastrin level was determined with a suspect of gastrinoma. And an increase of serum gastrin was demonstrated. In addition, postmortem histological examination revealed that the pancreatic cells were positive for gastrin. Based on these findings, the dog was diagnosed as pancreatic gastrinoma.

Gastroduodenal ulceration in cats: eight cases and a review of the literature

Gastroduodenal ulceration (GU) and blood loss was diagnosed in eight cats and compared with 25 previously reported cases of feline GU. Cats with GU presented in a critical condition. Clinical signs consistent with gastrointestinal bleeding were infrequently identified although anaemia was a common finding. Non-neoplastic causes of feline GU tended to have a shorter clinical course with ulcers confined to the stomach. Conversely, cats with tumour-associated GU usually had a more protracted clinical course, weight loss, and ulcers located in the stomach for gastric tumours and the duodenum for extra-intestinal tumours. In this series, definitive diagnosis was possible for cats with neoplasia (gastric tumours and gastrinoma), however, it was difficult to precisely identify the underlying aetiology in cats with non-neoplastic GU. Prompt stabilisation with a compatible blood transfusion, surgical debridement or resection, antibiotic and antiulcer therapy, and treatment of the underlying disease, if identified, was successful in the majority of cases. The prognosis for cats with appropriately managed GU depended on the underlying aetiology, but even cats with neoplasia could be successfully palliated for prolonged periods.