Stomach Cancer in Dogs and Cats - Symptoms and Diagnosis

How does stomach cancer develop in dogs and cats?

Cancer, by definition, is the growth of abnormal cells in places where normal cells should be. These abnormal, neoplastic cells proliferate uncontrollably and can spread to other systems through metastasis. The cause behind the growth and development of cancer cells is not fully understood, but there are risk factors that have been shown to increase the chances of cancer development in dogs and cats.

Cancer cell growth is often a result of a genetic mutation of normal cells and as such shares some properties with normal cells including their functions. There are different types of stomach cancer in pets depending on the tissue they have originated from, and the treatment approach often depends on the type of stomach tumor present in the pet.

Risk Factors of Stomach Cancer Development

Several risk factors can predispose to stomach cancer development in dogs and cats. Stomach cancer appears to be more common in males than females and usually starts to appear at a mean age of 9 years and older.

Certain breeds of dogs such as Collies, Chow Chows, and Staffordshire Terriers have more risk of stomach cancer development. In cats, Siamese breeds are reported to be at higher risk of developing gastric adenocarcinomas compared to other breeds.

Types of Stomach Cancer in Dogs and Cats

The most common stomach cancer reported in dogs is adenocarcinomas. They usually affect the lower third of the stomach and often spread or metastasize to nearby structures such as lymph nodes and the liver. Gastric adenocarcinomas originate from the enzyme-producing cells along the mucosal lining of the stomach, and functional adenocarcinomas often produce excessive digestive enzymes that contribute to the clinical signs of the condition.

Less common stomach cancers in dogs include leimyelomas, mast cell tumors, and lymphoma.

In cats, the most common stomach cancer is lymphoma. Lymphoma in cats can be low-grade or high-grade, both of which have different clinical presentations.

Adenocarcinomas in a cat’s stomach are uncommon but are biologically active and have high rates of metastasis.

Symptoms of Stomach Cancer in Pets

Symptoms associated with stomach cancer in both dogs and cats depend on how extensive the cancer is. Initial clinical signs of stomach cancer cases include vomiting, anorexia, and lethargy.

Vomiting is often profuse and will contain gastric acid and occasionally, blood.

Abdominal pain may also be present in pets with stomach cancer. If the tumor becomes bigger or is located near the pylorus (segment of the stomach that opens to the small intestine), obstruction may occur and can result in profuse vomiting and eventual weight loss.

In some cases, stomach cancer can cause a decline in the body’s blood sugar level causing severe weakness, tremors, and possible seizures.

Some types of stomach cancer can cause chronic damage to the stomach wall and result in gastric perforations. Damage along the lining of the stomach causes hemorrhage which can be observed from the vomit or can show as a black, tarry stool if blood is ingested. Perforations along the gastric wall will result in gastric contents leaking out to the abdominal cavity, causing peritonitis, a condition that can be fatal if not addressed immediately.

How are stomach cancers diagnosed?

Stomach cancer patients will usually have general signs of illness at the early stages of the disease. Since stomach cancer is uncommon in both dogs and cats, it’s usually only suspected when common causes of vomiting have been ruled out already and clinical signs persist despite initial treatment.

Dogs that present with general signs of gastrointestinal problems like vomiting, lethargy, and inappetence will often undergo basic diagnostic tests such as blood work and diagnostic imaging.

Diagnostic imaging such as contrast radiography can show signs of possible obstruction or growths along the gastrointestinal tract. The ideal test to visualize stomach cancer is endoscopy, where an instrument is inserted inside the intestinal lumen through the mouth for real-time visualization of the intestinal or gastric lining. It allows for a more accurate and descriptive visualization of growths, tissue damage, and perforation along the mucosal lining of the stomach.

Definitive diagnosis will come from gastric biopsies. A biopsy test is a process of obtaining tissue samples from any part of the body for analysis and histopathology. This procedure helps confirm if growths observed on the surface of the stomach are cancerous or not. It also allows for proper grading of stomach cancer and identification of the type of stomach cancer that is present.

A biopsy can be done in several ways. The most common and least invasive biopsy is through the use of an endoscope. Most endoscope instruments have partitions that allow attachment of biopsy instruments. Through an endoscope, your veterinarian will be able to visualize and obtain samples from stomach tumors without having to make an incision to access the abdominal cavity.

Another way to obtain samples from stomach tumors for diagnosis is through exploratory laparotomy. This is a surgical procedure that is done to be able to visualize abdominal organs and obtain samples if necessary. Unlike endoscopic biopsy procedures, exploratory laparotomy will involve a surgical incision to gain access to abdominal organs.

Regardless of the method, samples taken for biopsy can be submitted to a histopathology laboratory for confirmatory diagnosis and grading of stomach cancer in both dogs and cats.

Read more:

Cancer (Neoplasia) in Cats

Warning Signs of Cancer in Dogs

Stomach Ulcers in Dogs and Cats

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