top of page
  • Writer's pictureClayton Watkins, DVM

Stomach Cancer in Dogs: 7 Symptoms To Look Out For

Stomach cancer in dogs is a serious medical condition that requires prompt diagnosis and treatment. Though less common than other types of cancer, it is often aggressive and can spread rapidly, affecting both the quality of life and lifespan of the animal. This comprehensive guide aims to help pet owners understand the complexities of stomach cancer in dogs, from its causes and symptoms to diagnosis and treatment options.

dog with nasal tumor

Looking for a specific answer? Use our guide below to quickly navigate to your desired section:

What is Stomach Cancer in Dogs?

Stomach cancer, also known as gastric cancer, refers to the uncontrolled growth of malignant cells within the stomach lining or wall. These cancerous cells can form tumors and may metastasize, spreading to other parts of the body, such as the lymph nodes, liver, or lungs. The most common types of stomach cancer in dogs are adenocarcinoma, lymphoma, and leiomyosarcoma. Each type varies in terms of aggressiveness, rate of growth, and prognosis, but all require immediate medical intervention.

What Causes Stomach Cancer?

The exact cause of stomach cancer in dogs remains unclear, although there are various factors that may contribute to its development. These include:

  • Age: Stomach cancer is more commonly observed in older dogs, typically those over the age of eight.

  • Genetics: Some breeds are more susceptible to stomach cancer, including Chow Chows, Belgian Shepherds, and Standard Schnauzers.

  • Diet: Dogs fed low-quality diets high in preservatives and additives may have an increased risk of developing stomach cancer.

  • Environmental Factors: Exposure to toxic chemicals, secondhand smoke, and other environmental pollutants can also be contributing factors.

  • Chronic Gastritis: Long-term inflammation of the stomach lining may predispose a dog to developing gastric cancer.

Understanding these potential contributing factors can help in the early identification and prevention of this devastating disease.

Can You Prevent Stomach Cancer?

While there is no way to completely prevent stomach cancer in dogs, there are several proactive measures that can be taken to minimize risk factors and improve overall health.

  • Balanced Diet: Feeding your dog a high-quality, balanced diet rich in essential nutrients can strengthen their immune system and possibly lower the risk of developing cancer.

  • Regular Veterinary Check-ups: Routine veterinary screenings, including blood tests and ultrasound, can help in the early detection of abnormalities, including cancerous growths.

  • Avoid Exposure to Toxins: Limiting your dog’s exposure to harmful chemicals such as pesticides, herbicides, and secondhand smoke can reduce the risk of developing cancer.

  • Exercise and Weight Management: Regular exercise helps in maintaining an ideal weight, which can also reduce the risk of various types of cancers.

  • Genetic Testing: If your breed is particularly susceptible to stomach cancer, consider genetic testing to assess your dog's individual risk profile.

By taking these precautionary steps, you may not completely eliminate the risk, but you can certainly make strides in promoting a healthier, and hopefully cancer-free, life for your dog.

7 Symptoms of Stomach Cancer in Dogs

Recognizing the early symptoms of stomach cancer in dogs can be challenging due to the subtle nature of clinical signs and similarity to other gastrointestinal disorders. Here is a detailed breakdown of the various symptoms you should be aware of:

1. Loss of Appetite

A significant change in eating habits, including a reduced appetite, is one of the first warning signs of stomach cancer in dogs. If your dog suddenly seems disinterested in food or leaves meals unfinished, consult your veterinarian for a comprehensive examination.

2. Weight Loss

Unexplained weight loss can accompany loss of appetite and is often a red flag. The absence of other causes, like a change in diet or increased physical activity, makes this symptom especially concerning. A dog losing weight rapidly without an evident reason needs immediate veterinary attention.

3. Vomiting

Frequent episodes of vomiting, sometimes with blood, could indicate stomach cancer. This occurs because the cancerous the cancer causes inflammation in the stomach wall leading to nausea and subsequent vomiting. Please note the frequency, timing, and appearance of vomit for accurate diagnosis.

4. Abdominal Pain or Discomfort

A dog with stomach cancer may experience abdominal pain or discomfort, exhibited by hunched posture, excessive panting, or restlessness. You may also observe that your dog is reluctant to lie down on their belly or shows sensitivity when touched around the abdomen. Stomach cancer often becomes ulcerated leading to pain and bleeding.

5. Lethargy

A general decline in activity levels and enthusiasm for activity can be another sign of stomach cancer in dogs. Lethargy may manifest as a lack of interest in walks, playtime, or other activities your dog used to enjoy.

6. Blood in Stool or Black, Tarry Stools

Blood in the stool or black, tarry feces are symptoms that should never be ignored. These could be indicative of internal bleeding caused by a cancerous growth in the stomach. Immediate veterinary evaluation is required for diagnosis and treatment planning.

7. Difficulty Swallowing

Although less common, difficulty in swallowing can sometimes be seen in dogs with cancer of the esophagus or mouth. The mass causes blockage, affecting the smooth passage of food.

Understanding these symptoms can assist in the detection of stomach cancer in dogs. However, it is important to consult your veterinarian for a definitive diagnosis and treatment plan if any of these symptoms persist.

How Quickly Can Stomach Cancer Form and Progress?

The formation and progression of stomach cancer in dogs can vary widely depending on several factors, such as the type of cancer, stage of discovery, and overall health of the dog. Some aggressive forms of cancer can spread rapidly within weeks to months, whereas others may take up to a year develop to a stage where symptoms become noticeable.

How Stomach Cancer is Diagnosed in Dogs

The diagnosis of stomach cancer in dogs involves a multi-step approach that combines clinical evaluation with several diagnostic techniques. Here are some commonly employed methods:

Physical Examination

A thorough physical examination by a veterinarian is the first step in the diagnostic process. The veterinarian may examine the oral cavity, palpate the neck and palpate the dog's abdomen to detect any abnormal masses or areas of discomfort that could indicate cancer.

Blood Tests

Complete blood counts, biochemical profiles, and other blood tests provide valuable information about the overall health of the dog and can indicate whether the body is fighting off an infection or disease. Elevated white blood cell counts, anemia, or other irregularities can be indicators of cancer or other systemic issues.


Radiographic images of the abdomen can offer initial insights into the presence of tumors or masses within the stomach. Although X-rays may not always provide conclusive evidence of cancer, they are useful for ruling out other conditions that might cause similar symptoms.


An abdominal ultrasound offers a more detailed view of the internal organs, including the stomach. This non-invasive technique allows the veterinarian to assess the texture, size, and location of any suspicious growths or lesions in the stomach lining.


This procedure involves inserting a flexible endoscope attached to light source and camera into the dog's stomach through the mouth. The endoscope allows for real-time visualization of the stomach lining and is helpful for identifying abnormal tissue or growths. Biopsy samples can be taken during this procedure for further analysis.


A biopsy is required for diagnosing stomach cancer. Tissue samples, collected either through endoscopy or ultrasound-guided, are examined under a microscope to determine the type of cells involved and whether they are benign or malignant.

CT/MRI Scans

Advanced imaging techniques like computed tomography (CT) may be recommended in some cases to assess the extent of the cancer and whether it has spread to other parts of the body.

Each diagnostic technique has its advantages and limitations, and often multiple methods are combined to arrive at an accurate diagnosis. Immediate and appropriate diagnosis is essential for the effective treatment and management of stomach cancer in dogs.

Treatment Options For Stomach Cancer in Dogs

The treatment for stomach cancer in dogs is multidisciplinary and often involves a combination of surgical, medical, and radiation therapies. The best approach depends on various factors like the type and stage of cancer, the overall health of the dog, and the availability of specialized treatments. Here are some commonly employed treatment options:

HDR Brachytherapy

High Dose Rate (HDR) Brachytherapy is a form of internal radiation therapy that delivers a high dose of radiation directly to the tumor site, minimizing damage to surrounding tissues. VetMed specializes in this innovative and minimally invasive technique. Its application is limited to cancer of the mouth and esophagus. Cancer in the stomach requires external beam radiation therapy, a technique where the radiation is targetd to the mass from the outside in.


Surgical removal involves making an incision in the abdomen to access the stomach and excising the cancerous growth. The goal is to remove as much of the tumor as possible while preserving the surrounding healthy tissue. However, surgery may not be an option if the cancer has spread to other parts of the body.


Chemotherapy involves the use of anti-cancer drugs to kill or inhibit the growth of cancer cells. This treatment is usually considered when the cancer has metastasized or when surgical removal is not feasible. Chemotherapy can be administered orally or intravenously and is often used in conjunction with other treatments.

Radiation Therapy

Conventional radiation therapy uses high-energy radiation to target and kill cancer cells. This treatment is most effective for localized tumors and can be employed post-surgery to eliminate any remaining cancerous cells. It's also an option for dogs that are not surgical candidates due to health reasons or the location of the tumor.


This is an emerging field in veterinary oncology that focuses on enhancing the dog's immune system to fight cancer cells. Though not commonly used for stomach cancer, it's an area of ongoing research and could offer new avenues for treatment in the future.

Palliative Care

For cases where curative treatment is not possible or the side effects of treatment are too severe, palliative care focuses on providing relief from symptoms and improving the quality of life. This can include pain management, nutritional support, and other symptom-control measures.

Each treatment option has its own set of pros and cons, and the best approach is often a combination of these methods tailored to the individual needs of the dog. Consultation with a veterinary oncologist is crucial for determining the most effective treatment plan.

Recovery and Management For Stomach Cancer in Dogs

Recovery and management following treatment for stomach cancer in dogs is complex and requires a multidisciplinary approach. Aftercare often depends on the type of treatment received, the extent of the disease, and the overall health status of the dog. Below are key aspects of recovery and management:

Post-Surgical Care

If surgery was performed to remove the tumor, close monitoring in the immediate post-operative period is important. Dogs may require pain medication, intravenous fluids, and antibiotics to prevent infection. A gradual return to normal activity is generally recommended, with frequent check-ups to assess wound healing and any signs of complications.

Monitoring and Follow-up

Regular follow-up appointments with a veterinary oncologist are essential for tracking the dog's response to treatment. This typically involves periodic imaging studies, like endoscopy, ultrasound or CT

Nutritional Support

Dogs with stomach cancer often experience weight loss, loss of appetite, and malabsorption of nutrients. A specialized diet rich in protein and essential nutrients, possibly recommended by a veterinary nutritionist, can help improve the dog's overall health and tolerance to treatment.

Medication Management

Whether your dog is on chemotherapy, pain medication, or other forms of drug therapy, proper medication management is essential. Dosages may need to be adjusted based on your dog's response to treatment and any side effects experienced.

Emotional Support

A cancer diagnosis and the ensuing treatment can be stressful for both the pet and the owner. Providing a calm and loving environment can make a significant difference in your dog's mental health. Toys, gentle play, and affection can all contribute to improving your dog’s outlook and quality of life.

Palliative and End-of-Life Care

In advanced cases where curative treatment is not possible, the focus shifts to palliative care aimed at providing relief from symptoms and maintaining the best possible quality of life. This can include medications for pain and nausea.

Effective management and recovery are not just about eliminating the cancer but also about maintaining the highest quality of life for your pet.

VetMed Treats Stomach Cancer in Dogs

At VetMed, we're committed to providing the most comprehensive and compassionate care for dogs diagnosed with stomach cancer. Whether your pet is in the early stages of stomach cancer or dealing with a more advanced condition, our dedicated team at VetMed is here to offer exceptional care and various treatment options to help manage this challenging diagnosis. We're dedicated to improving the lives of our patients and giving pet owners peace of mind during this difficult journey.


Questions You've Asked Us About Stomach Cancer in Dogs

Still have questions? Contact us here - we promise we'll answer them.

What are the signs of stomach cancer in a dog?

The signs of stomach cancer in dogs can be varied but often include persistent vomiting, weight loss, lack of appetite, and abdominal pain. Lethargy and changes in bowel habits may also be observed.

How long do dogs with stomach cancer live?

Does stomach cancer hurt dogs?

What are the symptoms of end-stage cancer in dogs?

How fast does stomach cancer progress in dogs?


bottom of page