GI Lymphoma in Cats: Signs, Causes, Treatment Options

Finding out your cat has gastrointestinal lymphoma isn’t only scary, but it may be confusing, too. When you hear “lymphoma,” you may think of enlarged lymph nodes in the neck. However, lymphoma in cats is most common in their GI tract, specifically the stomach or small intestine. In fact, 50 to 75 percent of lymphoma cases in cats are GI lymphoma (1).

Here’s everything you need to know about GI lymphoma in cats, including signs, causes, and treatment options.

What Is GI Lymphoma?

Lymphoma is a cancer of a specific type of white blood cell called a lymphocyte. GI lymphoma in cats refers to lymphoma that develops in the gastrointestinal tract. While this is most often the small intestine, it can also develop in the stomach.

GI lymphoma affects cats similarly to other intestinal diseases. It’s common for cats with GI lymphoma to lose weight, have diarrhea, and vomit.

A cat can have small cell GI lymphoma or large cell GI lymphoma:

Small cell gastrointestinal lymphoma is more common and has a better prognosis when compared with large cell gastrointestinal lymphoma. Small cell GI lymphoma in cats is often treated at home with oral medications and has a longer survival time of two to four years. 

Large cell GI lymphoma in cats is more malignant and may require surgery and injectable chemotherapy to treat. Survival time for large cell GI lymphoma with treatment is usually six to nine months.

Other common locations for cats to develop lymphoma include the kidneys (renal lymphoma) and within the chest (mediastinal lymphoma). These forms of lymphoma will have different clinical signs, treatment recommendations, and prognoses.

Causes of GI Lymphoma in Cats

GI lymphoma develops when the lymphocytes in the gastrointestinal tract grow uncontrollably. The exact cause of GI lymphoma in cats isn’t known, and several factors could contribute to the development of this cancer.

One factor that has been suggested as contributing to the development of GI lymphoma is chronic inflammation in the gastrointestinal tract. Inflammatory bowel disease (IBD) occurs concurrently in up to 60 percent of GI lymphoma cases in cats (2). Over time, inflammation may lead to cancerous changes in the lymphocytes of the gastrointestinal tract.

Other potential factors being investigated include exposure to secondhand smoke and dietary factors, though definitive links have not been found. While other types of lymphoma in cats have been linked to the feline leukemia virus (FeLV) or feline immunodeficiency virus (FIV), most cats that develop gastrointestinal lymphoma are not positive for FeLV or FIV.

GI Lymphoma in Cats Symptoms

GI lymphoma most commonly develops in older cats between 9 to 13 years of age. Because the signs of GI lymphoma are similar to the symptoms of other gastrointestinal conditions like IBD, pet parents may not initially realize their cat has cancer.

The main signs to watch for include:

• Weight loss
• Vomiting
• Diarrhea
• Lethargy

Appetite changes aren’t always consistent in cats with gastrointestinal lymphoma. Some cats with GI lymphoma will have a normal appetite, some will have a reduced appetite, and some may seem like voracious eaters. 

Cat GI Lymphoma Stages

Staging has not been shown to predict outcomes for gastrointestinal lymphoma, so many veterinarians do not perform complete staging for cats with this form of cancer. 

Complete staging could involve:

• Abdominal ultrasound
• Chest X-rays
• Fine needle aspirates or biopsies of lymph nodes, liver, and spleen
• Stomach and/or intestinal biopsies
• Bone biopsy

Diagnosing GI Lymphoma in Cats

GI lymphoma may be suspected based on the clinical signs of weight loss, vomiting, and/or diarrhea in an older cat. During abdominal palpation, the veterinarian might notice thickened intestines or intestinal masses. Abdominal ultrasound often shows a thickened intestinal wall or intestinal masses. However, a biopsy is necessary for definitive diagnosis.

For most private practice veterinarians, biopsies will need to be collected surgically. The veterinarian will enter the abdomen and take several biopsies from the intestines and/or stomach while the pet is under general anesthesia.

Veterinarians with endoscopy may be able to take biopsies from the stomach or upper small intestine using their endoscope. If a mass is present, an ultrasound machine may be used to guide a needle into the mass to take a sample of cells. Biopsies are usually sent to a special pathology lab for interpretation.

Treating GI Lymphoma in Cats

Small cell lymphoma is usually treated at home with an oral steroid called prednisolone and an oral chemotherapy drug called chlorambucil. 

Large cell GI lymphoma is much more aggressive. If there is a single mass, surgery may be considered to remove the mass. Chemotherapy for large cell GI lymphoma usually follows the CHOP protocol, which involves several months of three chemotherapy drugs and prednisolone. This treatment is usually performed by a veterinary oncologist. 

Cost to Treat

The cost to treat will depend on the type of GI lymphoma and the treatment pursued. 

Chemotherapy can cost over $3,000, often ranging from $6,500 to $8,500 for the large cell lymphoma CHOP protocol. If surgery is pursued for an intestinal mass, the cost could range from $1,500 to over $3,000. 

Treatment for small cell lymphoma is generally less costly since medications can be purchased through various pharmacies and administered at home. Your cat will still need to see the veterinarian for regular rechecks and bloodwork.

GI Lymphoma in Cats Prognosis

Small cell GI lymphoma in felines has a better prognosis of two to four years with treatment. In older cats diagnosed with small cell GI lymphoma, they may end up passing away from another condition while undergoing treatment.

Large cell GI lymphoma is aggressive and carries a prognosis of six to nine months, even with treatment. 

How to Prevent GI Lymphoma

At this time, there is no sure way to prevent GI lymphoma in cats. Consider keeping your cat vaccinated and indoors to prevent contraction of FeLV or FIV, which could contribute to the development of other lymphomas. You should also reduce exposure to secondhand smoke.

If your cat is a frequent vomiter or has loose stools, consider seeing a veterinarian. Although it’s not a definitive link, chronic inflammation in the gastrointestinal tract may contribute to the development of GI lymphoma. Inflammatory bowel disease should be ruled out and, if present, controlled for your cat’s overall welfare.

Reference

1. Paulin, M.V., Couronné, L., Beguin, J. et al. Feline low-grade alimentary lymphoma: an emerging entity and a potential animal model for human disease. BMC Vet Res 14, 306 (2018). https://doi.org/10.1186/s12917-018-1635-5
2. Paulin, Mathieu V et al. “Feline low-grade alimentary lymphoma: an emerging entity and a potential animal model for human disease.” BMC veterinary research vol. 14,1 306. 11 Oct. 2018, doi:10.1186/s12917-018-1635-5