Gastrointestinal neoplasia is cancer located anywhere throughout the gastrointestinal (GI) tract, including the oral cavity (mouth), esophagus, stomach, small intestines, large intestines and rectum. GI cancer can be primary, which means it originates in the GI tract, or metastatic, which is spread from another site.

No specific causes of primary cancer have been identified, although it has been associated with several disorders. Chronic inflammation or irritation has been thought to be a contributing factor in some cases. Spirocerca lupi, a parasite of the esophagus, may cause associated cancer.

Cancer usually occurs in middle-aged to older dogs. Depending on the tumor type and location, different breeds, ages, and species can be affected. The Belgian shepherd and Scottish terrier have a higher incidence of gastric carcinoma than other breeds. Collies are also more likely to develop malignant intestinal cancer.

What to Watch For

With gastrointestinal cancer, clinical signs are largely dependent on the location of the cancer, size of the mass, and to a degree, the specific type of cancer. General signs to watch for by location include:

Oral. Watch for halitosis (bad breath), bleeding from the mouth, difficulty eating and drooling.

Esophageal. Watch for regurgitation, excessive salivation and weight loss.

Gastric (stomach). Watch for vomiting (with or without blood), weight loss, inappetence and black tarry feces.

Small intestinal. Watch for diarrhea, vomiting, weight loss, anorexia, black, tarry feces and gas.

Colonic (large intestinal). Watch for diarrhea (with mucus or blood) and straining to defecate.

Rectal. Watch for straining and blood in stool.

Diagnosis

Your veterinarian may recommend the following diagnostic tests:

Baseline tests to include a complete blood count (CBC), biochemical profile and urinalysis

Fecal examination

Abdominal radiographs (x-rays)

Thoracic (chest) radiographs

Abdominal ultrasound

Upper gastrointestinal contrast radiography (dye study)

Endoscopy of the upper and/or lower bowel and biopsy

Abdominal exploratory and biopsy

Treatment

Hospitalization and support as needed, such as fluid therapy or blood transfusions

Surgical resection (removal), which is the treatment of choice

Surgical debulking (removing as much as possible) to help improve clinical signs

Chemotherapy

Radiation therapy

Dietary manipulation

Home Care

Administer medication and diet as directed by your veterinarian. Return for follow-up as directed by your veterinarian. If your pet has a recurrence of signs, contact your veterinarian at once.

Prognosis varies depending on the location, size, type and ability to remove the tumor surgically.

There is no known specific prevention of gastrointestinal cancer. Treat all underlying inflammatory disorders in their early stages if possible.