Stomach (Gastric) Cancer in Cats and Dogs
What are stomach tumors?
The stomach is a muscular organ of the gastrointestinal tract that holds food and begins the digestive process by
secreting gastric juice. The most common cancers of the stomach are adenocarcinomas but other histological types have
been reported (eg gastrointestinal stromal tumors,
leiomyosarcoma, lymphoma, mast cell tumor, extramedullary
fibrosarcoma). Adenocarcinomas will frequently spread to lymph nodes, followed by liver and lung.


How common are these tumors?
Gastric  cancer accounts for less than 1% of all cancers. Gastric adenocarcinoma is rare in cats and most cats are
affected with lymphoma. The average age of affected pets is 8 years and males appear to be affected more often
compared to females.

What are the symptoms of stomach cancer in cats and dogs?
The most common symptom of gastric cancer is vomiting (often with blood), weight loss due to poor digestion and loss of
protein, or generalized weakness. The duration of symptoms can range from weeks to months.

How is the diagnosis of stomach cancer made in cats and dogs?
Standard laboratory tests or noncontrast X-rays are generally not very helpful. In order to determine whether a tumor is
present in the stomach, the veterinarian can perform special X-rays (called positive- or double-contrast radiography)
abdominal ultrasound. Gastroscopy, a test using an instrument called endoscope to examine the stomach, is a
useful diagnostic tool that can also collect
biopsy samples of the suspected mass for further analysis to confirm or rule out
cancer. The most definitive method of cancer diagnosis is through open surgical
biopsy, and in case of gastrointestinal
stromal tumors, CD117 immunohistochemical stain is recommended for confirmation.

Do these tumors cause pain?
It is imperative that pets with cancer are provided with pain medication to relieve discomfort caused by the disease as well
as by the treatments. To learn more, please visit the
Cancer Pain Management section.

What food should be fed to pets with cancer?
Pets with cancer need to be fed diets specifically designed to support a cancer patient. To learn more, please visit the
Cancer Nutrition

What are the treatment options for stomach cancer in cats and dogs?
Except for lymphoma, surgery is the most frequent treatment option for stomach cancers. If the cancer appears to be
localized without having spread to other organs, the excision of the tumor may achieve substantial benefit to the pet. The
complexity of the surgery will vary from one pet to another depending on the tumor's characteristics, size and location. In
the cases where the tumor blocks passage of food from the stomach to the intestine, it may be possible to perform bypass
surgery for palliative reasons (provide relief) rather than intent to cure. There are risks associated with gastric surgery
and pet owners should discuss these in great detail with their surgeon.

Radiation therapy is rarely applied in the case of stomach tumors due to the high risk of harming nearby organs such as
the liver and intestine and no
chemotherapy protocols have been shown to provide significant benefit to date.

Finding a qualified veterinary oncologist
To locate a qualified veterinary oncologist in your area who can discuss with you appropriate cancer treatment plan for
your pet's cancer condition, please visit the "
Locate a veterinary oncologist" section.  

Are there any clinical trials investigating new treatments for stomach cancer in cats and dogs?
There are no clinical trials specifically designed for stomach tumors in pets, however, there are several clinical trials
available for cats and dogs with any tumor type for which your pet may qualify. To learn more these trials (which are
partially or fully funded by the institutions), please visit the
Dog Clinical Trials (any tumor type) or Cat Clinical Trials (any
tumor type) section.  

To learn more about veterinary clinical trials in general, please visit the
Pet Clinical Trials section.

What is the prognosis of stomach cancer in cats and dogs?
Unfortunately, the prognosis for pets diagnosed with malignant stomach cancer is generally poor but benign tumors can
be successfully removed by surgery. Even if surgery is possible, most pets die within 6 months due to recurrent cancer
(cancer that came back in the stomach) or metastatic cancer (cancer that spread to other organs). One study showed
that of 17 dogs that were treated with surgery for gastric adenocarcinoma, the median survival was 2 months. In rare
cases, the pets survived as long as 3 years. Another study showed that of 7 dogs diagnosed with leiomyosarcoma that
were treated with and survived the surgery , the median survival was 1 year. Less than 10% of pets diagnosed with
gastrointestinal mast cell tumors survived 6 months.  

  • Withrow Stephen J, and David M. Vail. Small Animal Clinical Oncology. St Louis: Saunders Elsevier, 2007.
  • Morrison Wallace B. Cancer in Dogs and Cats: Medical and Surgical Management. Baltimore: Williams&Wilkins,
Comprehensive guide to cancer diagnosis and treatment in cats and dogs
© 2007 Pet Cancer Center. ALL RIGHTS RESERVED.
Last updated 2/19/2017