Stomach Cancer in Dogs: What To Expect, Signs, Treatment Options

Stomach Cancer in Dogs

Stomach Cancer in Dogs: What To Expect, Signs, Treatment Options

Gastrointestinal cancer or gastric adenocarcinoma is not a common form of cancer in dogs and accounts for less than 1% of all abnormal growths in the intestinal region. Unfortunately, it can develop undetected and affect the health of your pet without warning.

When malignant tumors are detected inside the stomach, immediate treatment is necessary to prevent them from spreading. It’s essential for dog owners to learn about the symptoms of this lethal disease before it reaches a terminal stage.

We are discussing the details about stomach cancer in dogs, along with the various forms of diagnosis and treatment.

Key Takeaways

  • Canine stomach cancers can be of various types, among which adenocarcinomas and gastrointestinal stromal tumors (GISTs) are two common ones.
  • Frequent vomiting, abdominal pain, lethargy, low appetite, and weight loss are a few but major signs of stomach cancer in dogs.
  • Surgery is the most common form of treatment even though the prognosis is mostly negative.
  • Consider the qualitative and quantitative aspects of a dog’s life before opting for euthanasia.

Types of Stomach Tumors in Dogs

Stomach cancer in dogs is generally classified into five types. Even though gastric tumors are rare, the prognosis for most types is poor [1].


The majority of stomach cancers are gastric adenocarcinoma. These tumors form in the innermost lining of the stomach called the mucosa. 

This type of tumor tends to spread quickly to other organs, like the liver, lungs, or pancreas. Furthermore, the tumor has a tendency to affect the entire digestive tract including the small and large intestines.

The prognosis of adenocarcinomas is not always positive, and the majority of dogs have a survival time of fewer than 6 months [2].

Gastrointestinal Stromal Tumors (GISTs)

Very little is known about the development of GISTs in the body. However, the formation of canine and human GISTs have a common molecular model [3]. These tumors form in special cells of the gastrointestinal tract called the interstitial cells of Cajal, which control the movement of the muscles in the intestine.

While these tumors can form anywhere along the canine GI tract, they are mostly formed in the stomach. The size and location of the tumor are what determine the rate of its growth.

Mast Cell Tumors 

This form of tumor develops from the “mast cells,” which are a part of the immune system. These cells control inflammation and allergic reactions in the animal. Mast cell tumors are usually located in one spot, however, they can spread to the lymph nodes, blood, liver, spleen, and skin cells.

While some of these tumors can remain inactive for years, others may spread rapidly and create severe complications like stomach ulceration and bleeding. This tumor is more common in some dog breeds like the Boston Terriers, Bulldogs, and Boxers.

stomach cancer in dogs
The survival probability for dogs with mast cell tumor is 95% at six months and 86% t five years


Leiomyosarcoma is a rare tumor that occurs in the smooth muscles lining hollow organs like the stomach, bladder, and uterus. It is classified as a soft tissue sarcoma. One of its characteristics is an aggressive growth rate that allows it to spread to the liver and spleen.

The tumor can cause perforations in the stomach walls if left unchecked. Even after surgical treatment, the survival time for most dogs is only a few months.

Signs of Stomach Cancer in Dogs

The clinical signs of stomach cancer are often similar to chronic gastritis. The time period of the symptoms can vary between 4 and 18 months [4]

Some of the common signs and symptoms of cancer in dogs are listed below:

  • Vomiting
  • Abdominal distention or abdominal discomfort
  • Weight loss
  • Anorexia
  • Haematemesis or vomiting blood
  • Anemia
  • Melaena
  • Lethargy
  • Loss of  appetite
  • Ptyalism or excess saliva generation
  • Polydipsia or extreme thirst

In some cases, the pet can develop hypoglycemia or below-normal blood glucose. This can lead to restlessness, weakness, seizures, or disorientation. There can be a behavioral change in the pet due to abdominal pain if the cancer has advanced or spread to other organs.

What Causes Stomach Cancer in Dogs?

A combination of multiple risk factors is believed to be the reason behind most tumors in dogs. These can include genetics, sex, age, diet, lifestyle, and environmental factors.

Data indicates gastric carcinoma is more common in aged dogs, particularly dogs above 9 years of age. Males are usually at higher risk than females.

Dog food with nitrates and NDMA can increase the risk of gastric carcinoma [5]. The risk factor is also increased by salt and salt-preserved foods. More detailed studies are required to confirm these findings, however.

What Breeds Get Canine Stomach Cancer?

Gastric carcinoma has been linked to genetic traits [4]. Here are some breeds that are at higher risk:

  • Tervuren
  • Bouvier des Flandres
  • Collie
  • Staffordshire Terriers
  • Standard Poodle
  • Norwegian Elkhound
  • Belgian Shepherds
  • Groenendael
  • Chow Chow

Diagnosis of Canine Gastrointestinal Cancer

It is difficult to confirm gastric adenocarcinoma from the external symptoms alone, therefore, the diagnosis involves multiple steps. 

stomach cancer in dogs

Physical Examination

A preliminary diagnosis of gastric carcinoma involves a review of the dog’s medical history along with a physical examination. Feedback about symptoms like weight loss, vomiting, lethargy, etc. is also taken from the owner. The vet may be able to feel a tumor if the dog’s stomach is enlarged.

Imaging Tests

The next stage of tests includes x-rays and abdominal ultrasound. X-rays of the abdominal region can help in detecting the size and spread of the tumor. Ultrasound is effective for checking the condition of the stomach wall lining or the inflammation of the lymph nodes post tumor detection.

Another common test is an endoscopic examination of the stomach. This allows a closer inspection of the mucosa and any irregularities within the stomach walls. 

The presence of ulcers can also be detected through endoscopy, and it’s commonly used to collect tissue samples for biopsy to determine if the tumor is malignant.


Blood tests are usually performed to check for various issues often related to or considered signs of cancer, including:

  • Anemia
  • Hypercalcemia
  • Hyperglobulinemia

Bloodwork is also commonly done to check for elevated lymphocyte count, which could indicate an infection, and check the condition of vital organs, including the liver and kidneys.


Detection of certain urinary excretory proteins through urinalysis can confirm the presence of stomach cancer. Besides, an advanced stage of stomach cancer can spread into the ureters and the urethra. Urinalysis is often used for detecting bladder cancer in dogs.


A biopsy is conducted on a tissue sample collected from a suspected spot in the stomach through an upper endoscopy. The analysis of the sample can confirm the presence of cancer, determine the type of tumor, and help in establishing the stage of the disease. 

An examination of the tumor and the presence of certain proteins is useful to plan the treatment.

Treatments for Dog Stomach Cancer

The most effective treatment for localized canine adenocarcinoma is surgery. Other treatments like chemotherapy and radiation can be combined with surgery based on the reports and symptoms.

stomach cancer in dogs


The prime form of treatment is removing the affected part of the stomach by surgery. A minor section of the small intestine is also removed in some cases. 

During surgery, the veterinary surgeon first drains any fluid from the stomach. In the next stage, the removal of the tumor or tumors takes place. Once the procedure is complete, the abdominal opening and the outer incision are sutured back. Monitoring the surgery with an electrocardiogram is standard practice.

Dog Stomach Tumor Removal Cost

In general, the cost can range between $1000 to $5,000 based on certain factors. If a blood transfusion is required during surgery, extra charges will apply.

The cost of gastrointestinal surgery for dogs depends on the size and stage of the tumor, and the general health condition of the dog. 

Radiation Therapy

Radiation therapy is effective for localized tumors that cannot be removed through surgery. During the process, a high-energy x-ray beam or other forms of radiation are used to destroy the malignant cells. The animal is placed under sedation to prevent any movement during the procedure.

A specific number of sessions are set over a period of time. The number depends on the severity of cancer. Radiation therapy is also used after surgery to remove any remaining cancer cells from the dog’s body.


Chemotherapy uses antineoplastic (antitumor) drugs to destroy the malignant cancer cells and prevent them from multiplying. This is used once the surgical procedure is complete to remove any remaining tumor cells. Chemotherapy can also be combined with radiation therapy.

There is no set standard for chemotherapy and multiple varieties of drugs can be used via pill form or injection. The duration of the chemotherapy treatment can vary depending on the type and stage of cancer.

Clinical Trials for Dogs With Stomach Cancer

Clinical trials are offered in multiple veterinary colleges across the country to offer new treatments for canine cancers. One objective of these trials is to study the approach for the treatment so that they can be extended to cancer treatments in humans.

In this field of comparative oncology, new trials are carried out to learn more about the different forms of the disease. However, the trials require a specific set of qualifications which may include the dog’s breed, age, and type of cancer.

Canine Stomach Cancer: What To Expect

Generally, the prognosis for canine stomach cancer is not positive. The survival time is usually less than six months and there are chances of the tumor growing back. Other risk factors include complications with anesthesia, infections, and ulcer development.

An invasive surgical process will need a proper recovery period and the dog will need special care depending on the dog’s age, health, and the nature of the procedure. It is important to allow your pet to rest and relax in a comfortable place. 

The standard period of recovery is around four to six weeks. Staying away from any strenuous activity and proper rest will help in speeding up the recovery process.

You must stick to the medications prescribed by the veterinarian. These usually include antibiotics and anti-inflammatory medication. If the animal appears nauseated or is vomiting frequently, consult your vet for help.

Check the wound site for any signs of infection—pus or drainage, hot to the touch, or bad smell—follow any wound care process specified by the doctor. In the later stages, you can take the help of veterinary rehabilitation centers to form a proper rehabilitation plan for your pet.

What To Feed a Dog With Stomach Cancer

It is common for the dog to experience loss of appetite after surgery. Avoid feeding rich dog foods that can tempt your dog to overeat. Your vet will likely guide you to the best food options by planning a nutrient profile that can aid in recovery. 

The dog should also have easy access to drinking water. However, if the animal is groggy or sleepy after surgery, precautions should be taken to prevent any chance of drowning.

Some pet owners have mentioned the positive effects of hemp for fast recovery and pain relief after surgery. Hemp contains cannabidiol (CBD) and delta-9 tetrahydrocannabinol (THC). 

There has been some evidence of the positive role played by hemp-derived CBD in controlling osteoarthritis-related pain in dogs [6]. The study has also indicated no side effects related to the CBD treatment.

However, the lack of detailed researched-based data makes the effective use of CBD challenging for veterinary use. The fact that the amount of CBD varies in different varieties of cannabis makes the use more difficult.

When to Euthanize a Dog With Stomach Cancer

The decision to euthanize will depend on the dog’s quality of life, age, and lifestyle. In extreme stages of the disease, the quality of life can become too low for the animal to continue living. 

By observing the signs of pain and discomfort in the animal, the possibility of preventing any further suffering can be discussed within the family. Some dogs may show signs like whimpering, crying, the inability to move or eat, or vomiting, which might be an indication that it is time to end the suffering.

Beyond that, there may not be any further treatments available or the expenses may be too high. Ultimately, the decision to euthanize will depend on the joint assessment of the veterinarian and the pet owner.


Here are a few FAQs related to canine gastric cancer.

Is Stomach Cancer in Dogs Painful?

In some cases it is. The behavior of the animal is an indication of the amount of pain it is suffering from. Touching the abdominal area can often make the dog wince in pain.

How Long Can Dogs Live With Intestinal Cancer?

If cancer has advanced or metastasized through the intestine or other organs, the median survival time is around three months.  When there is no metastasis, the median survival time is 15 months [7].

What Happens When a Dog Gets Stomach Cancer?

Evaluation of the dog’s condition is done through tests to determine whether the tumor is malignant or benign. The next step is the formation of a primary treatment plan based on the test reports and symptoms.


Dealing with cancer in dogs can be an overwhelming experience. Therefore, pet owners need to stay vigilant in order to spot any signs that might indicate gastric tumors. Early detection can be a key to successfully treating the tumors and prolonging the life of your pet. 

Ultimately, it is important that you follow the advice of the vet in every step to deal with the medical and emotional aspects related to the health of your pet.


  1. “Stomach Tumor.” Stomach Tumor – an Overview | ScienceDirect Topics,
  2. Lee, Hee-Chun, et al. “A Case of Gastric Adenocarcinoma in a Shih Tzu Dog: Successful Treatment of Early Gastric Cancer.” The Journal of Veterinary Medical Science, The Japanese Society of Veterinary Science, July 2014,
  3. Gregory-Bryson, Emmalena, et al. “Canine and Human Gastrointestinal Stromal Tumors Display Similar Mutations in c-KIT Exon 11.” BMC Cancer, BioMed Central, 15 Oct. 2010,
  4. Seim-Wikse, Tonje, et al. “Breed Predisposition to Canine Gastric Carcinoma—a Study Based on the Norwegian Canine Cancer Register.” Acta Veterinaria Scandinavica, BioMed Central, 21 Mar. 2013,
  5. Song, Peng, et al. “Dietary Nitrates, Nitrites, and Nitrosamines Intake and the Risk of Gastric Cancer: A Meta-Analysis.” Nutrients, MDPI, 1 Dec. 2015,
  6. Gamble, Lauri-Jo, et al. “Pharmacokinetics, Safety, and Clinical Efficacy of Cannabidiol Treatment in Osteoarthritic Dogs.” Frontiers in Veterinary Science, Frontiers Media S.A., 23 July 2018,
  7. Crawshaw J;Berg J;Sardinas JC;Engler SJ;Rand WM;Ogilvie GK;Spodnick GJ;O’Keefe DA;Vail DM;Henderson RA; “Prognosis for Dogs with Nonlymphomatous, Small Intestinal Tumors Treated by Surgical Excision.” Journal of the American Animal Hospital Association, U.S. National Library of Medicine,