Issue Description Gastrointestinal cancer refers to malignant
conditions of the gastrointestinal tract, including the esophagus,
stomach, liver, biliary system, pancreas, bowels, and anus. Other Names Gastrointestinal Cancer, Canine Gastrointestinal Cancer
Causes There are several different types of cancers
that are associated with stomach cancer in dogs.
Adenocarcinomas 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 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.
Lymphomas 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
Symptoms 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
Not willing to move
Vocalization (whining, growling)
Reacts to being touched in an unusual way (yelping, snapping
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.
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.
Prognosis 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.