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Stomach Cancer - Issue Description

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Issue Name

Stomach Cancer

Other Names
Canine Gastrointestinal Cancer, Gastrointestinal Cancer

Issue Description

Gastrointestinal cancer refers to malignant conditions of the gastrointestinal tract, including the esophagus, stomach, liver, biliary system, pancreas, bowels, and anus.


Gastrointestinal lymphoma causes vomiting, diarrhea, and melena (digested blood in the stool). Low serum albumin levels and hypercalcemia can also occur.

Cancer of the gastrointestinal tract will usually cause pain for the dog. Addressing pain should be part of the treatment plan in addition to treatment of the cancer and other symptoms. Dogs are not always obvious about being in pain.

Some of the signs that a dog is in pain are:

  • Lower activity level
  • Less social
  • Not willing to move
  • Vocalization (whining, growling)
  • Decreased appetite
  • Reacts to being touched in an unusual way (yelping, snapping running away)
  • Increased respiratory rate
  • Urinating or having bowel movements indoors
  • Unhappy demeanor and body language
  • Scratching or repeated licking of a particular body part

  • Diagnosis

    Diagnosis of stomach cancer involves taking a medical history and performing a physical examination and laboratory tests. A tumor or mass may indicate advanced disease. Tests may include fecal occult blood test, complete blood count (CBC), upper GI series (also called barium swallow), gastroscopy, and imaging tests. The veterinarian will decide what tests are right for the patient.


    There are several different types of cancers that are associated with stomach cancer in dogs.

    Adenocarcinomas are the type of tumors most often associated with cancer of the stomach. This cancer is one that is found in glandular tissue. This cancer will often spread to the liver, lungs, and lymph nodes.

    Mast Cell Tumors
    Mast cells are part of the immune system that have a role in inflammation and allergic responses. These cells are present in the linings of the digestive tract, lungs, nose, and skin. When mast cells become abnormal, they often form mast cell tumors. The tumors release excess amounts of the biological chemicals heparin and histamine which are normally produced by mast cells. This overdose of natural chemicals damages the body.

    Leiomyosarcomas are tumors that form in the walls of hollow organs such as the stomach, bladder, uterus and respiratory tract. The gastrointestinal tract is the organ that is most often affected by these tumors. This type of tumor, when found in the gastrointestinal tract, will often metastasize to the lymph nodes and liver. It can also spread to the spleen and kidneys.

    Lymphoma is a type of cancer that begins in white blood cells called lymphocites. Although lymphomas are not the most common cause of stomach cancer, these tumors can be found in the gastrointestinal tract. Dogs around the age of eight are most affected by this type of cancer.

    Breeds Most Often Affected

  • Boxers
  • Saint Bernards
  • Mastiffs
  • Airedales
  • Bulldogs
  • Scottish Terriers
  • Treatment

    If the cancer has not metastasized, surgical removal of the tumor is the most common and beneficial way to treat stomach cancer. This is the case with most tumors except lymphomas. If the tumor is preventing food from entering the stomach, bypass surgery is often helpful to the health of the dog, even though this surgery does not treat the cancer itself. Chemotherapy does not seem to be effective for cancer in the stomach. Radiation is dangerous to the delicate organs near the stomach and is rarely considered and option as a treatment for stomach cancer.


    Dogs diagnosed with malignant stomach cancer do not have an optimistic prognosis. Most dogs do not live beyond six months even with treatment. This is largely due to recurrence of the cancer or spread of the tumors to other organs. It is best to understand your dog's individual situation by discussing this diagnosis with the veterinarian.

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