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Gastric Neoplasia - Dog and Cat (view source)
Revision as of 10:53, 11 August 2009
, 10:53, 11 August 2009no edit summary
Aetiology largely idiopathic though long term ingestion of dietary carcinogens may have some responsibility. Long term administration of nitrosamines may cause carcinomas in dogs. In humans, the bacterium ''Helicobacter pylori'' can induce gastric carcinoma and lymphoma. Its role in gastric tumours in dogs and cats has not yet been fully established though it can cause gastritis and ulceration. Belgian Shepher dogs may have a genetic predisposition to gastric carcinoma. Cats with gastric lymphoma are not usually FeLV positive.
Aetiology largely idiopathic though long term ingestion of dietary carcinogens may have some responsibility. Long term administration of nitrosamines may cause carcinomas in dogs. In humans, the bacterium ''Helicobacter pylori'' can induce gastric carcinoma and lymphoma. Its role in gastric tumours in dogs and cats has not yet been fully established though it can cause gastritis and ulceration. Belgian Shepher dogs may have a genetic predisposition to gastric carcinoma. Cats with gastric lymphoma are not usually FeLV positive.
Adenocarcinomas: frequently metastasise to the regional lymph nodes (gastroduodenal and splenic lymph nodes), also the liver and sometimes the lungs. They are also locally aggressive and can cause stomach wall perforation and peritonitis. Other complications include:
* Pyloric outflow obstruction
* Ischaemic necrosis - tumour plugs and develop in the surrounding vasculature
Leiomyosarcomas: rarely metastasise.
Lymphoma: may be limited to the stomach or may affect lymph nodes and other abdominal organs or may be multicentric.
Plasmacytoma: frequently metastases are evident in local lymph nodes.
==Diagnosis== (based on typical history, clinical signs, physical exam findings, imaging/laboratory results)
==Diagnosis==
===History and Clinical Signs===
===History and Clinical Signs===
* Chronic vomiting - blood tinged/'coffee grounds' appearance
* May ne mild or non-specific early on in the disease process
* Chronic vomiting - blood tinged/'coffee grounds' appearance (partially digested blood)
* Weight loss
* Weight loss
* Anorexia
* Anorexia
* Maleana/occult faecal blood
* Anterior abdominal pain may or may not be present
===Haematology and biochemistry===
* Regerative anaemia - on account of gastric haemorrhage
* Electrolyte disturbances - secondary to vomiting
* Elevted BUN and creatinine - due to dehydration
===Positive Contrast Radiography===
The following abnormalities may be observed:
* Delayed gastric emptying
* Changes in motility in certain areas of the stomach
* Thickening of the gastric wall or ulceration
* Filling defects
* Loss of rugal folds
===Ultrasonography===
Characteristic features of gastric neoplasia are a thickened gastric wall along with disruption of the wall layers. Enlarged lymph nodes may be observed. The rest of the abdominal organs should be checked for metastases. Ulceration appears as a focal outpouching of the luminal (inner) surface with trapped gas bubbles.
===Endoscopy and Biopsy===
This allows direct visualisation of the lesion. Definitive diagnosis requires histolpathology. Biopsies can be taken via grab biopsy, however the sample may be unrepresentative. Alternatively, biopsies can be taken via gastrotomy at the time of surgical treatment (see below).
==Treatment==
==Treatment==
===Surgery===
Prior to any surgical intervention thoracic radiography should be performed for evidence of metastasis. Regional lymph nodes should also be examined along with the rest of the abdominal cavity. For tumours that have not metastasised, resection is the treatment of choice. However, excision with large margins whilst maintaining the ability to sucessfully reconstruct the stomach without post-operative complications can be problematic. Futhermore, pylorectomy and gastroduodenostomy or gastrojejunostomy for antral tumours risk iatrogenic injury to the local blood supply as well as the pancreas and extrahepatic biliary system. Post-operative complications are more frequent with resections associated with the pylorus. Neoplasia associated with the lesser curvature is generally unresectable.
===Chemotherapy===
For lymphoma only. There is an associated risk of gastric perforation.
===Radiotherapy===
Unreported
===Medical Management===
Symptomatic therapy of for example vomiting may improve quality of life in the short term - treatment options include anti-emetics such as metocolpramide and H2 blockers including ranitidine and cimetidine.
==Prognosis==
==Prognosis==
Variable:
* Benign tumours - Frequently cured by surgical resection. Prognosis good.
* Lymphoma - response to chemotherapy usually poor. Survival rates low.
* Most malignant tumours - usually associated with recurrent or metastatic disease. Prognosis therefore usually poor despite surgical resection. Survival time up to six months.
==References==
==References==