Carcinoma of the Pyloric Valve in Dogs

Function

• The pyloric valve, also called the pyloric sphincter, is a circular, constricting muscle located between the lower stomach and the duodenum (upper small intestine) of the dog. It opens to permit passage of ingested food and gastric juices into the duodenum and closes to prevent backflow of these substances into the stomach.

Types

• Due to its location, a carcinoma of the pyloric valve in dogs is most commonly a cancer of either the stomach or the intestines or both. Gastric adenocarcinomas are malignant cancers derived from glandular tissue (usually the stomach lining) and are the most common type of stomach and intestinal cancers in dogs. Gastric leiomyosarcomas are benign tumors made of smooth cells produced in muscular tissue. Adenocarcinomas are quickly progressive and often will metastasize to the liver, omentum, intestines, and kidneys before the dog presents any symptoms.

Symptoms

• Symptoms of canine gastric cancer are commonly very ambiguous; they can be signs of many different diseases. Projectile vomiting (sometimes with blood), weight loss, anorexia (an inability or unwillingness to eat), and diarrhea are usual signs of cancer and other illnesses. Normally, the only way to determine if the dog has cancer is through veterinary testing.

Diagnosis &Treatment

• Veterinarians will commonly start with diagnostic blood testing to determine organ function and chemical values in the animal's blood. Radiographs and an abdominal ultrasound may be recommended to determine the placement and size of possible stomach or intestinal tumors. Veterinarians may follow up with an endoscopy -- passing a tube down the dog's esophagus into the stomach to locate the lesion and take a sample for lab diagnosis. Needle biopsies of any found mass and surrounding lymph nodes may also be taken for further laboratory analysis. Once an animal is diagnosed with abdominal cancer, the first phase of treatment is usually surgical -- the veterinarian will attempt to remove the tumor with clean margins. Chemotherapy is also an option but long-term response to this form of treatment has not been shown to be effective. Veterinarians will normally not recommend radiation due to the possibility of compromising other organs in close proximity to the tumor.

Considerations

• Carcinoma of the stomach and intestines in dogs is commonly a disease of older dogs and is usually far advanced before the animal begins to show symptoms. Early diagnosis and treatment may result in remission for a few years, but the prognosis for these animals is normally poor with many cancers returning within a year of treatment. Veterinary care is commonly designed to reduce the symptoms of the disease and improve the quality of life for the dog. At some point, pet owners may need to consult with their veterinarian and consider euthanasia as a loving and humane option.