GI Lymphoma in Cats


Lymphoma is one of the most common malignancies in cats, and gastrointestinal or GI lymphoma in cats is an increasingly common problem. As with all varieties of this cancer, GI lymphoma is a disease of the lymphatic system, and targets cells called T- or B-lymphocytes.

Gastrointestinal lymphoma refers to lymphomas where the cancer appears in the small intestine, stomach, liver, abdominal lymph nodes, or large intestine. It can occur as focal tumors, which appear and grow in specific locations, or as diffuse growth, which causes a general thickening of the overall intestinal system.

Possible Causes

The exact causes of GI lymphoma in cats are unknown, although genetics are generally assumed to be the most important factor. Additional conditions that may cause GI lymphoma include feline leukemia virus (FeLV), which raises the overall risk for lymphomas by over 60 times, or feline immunodeficiency virus (FIV).

Symptoms and Diagnosis

GI lymphoma occurs mostly in older cats, from 9 to 13 years of age, and is most often detected in the small intestine. The following signs and symptoms may indicate that a cat has developed this kind of cancer:

  • Appetite loss or sudden weight loss
  • Irritability
  • Vomiting
  • Diarrhea
  • Lethargy
  • Refusing to be touched
  • Appearance of swollen or hard lumps in the abdomen

Only a veterinarian can make a definitive diagnosis, based on patient history, observed symptoms, and a physical examination. If GI lymphoma appears likely, your vet may order addition tests, like a biopsy of intestinal growths, x-ray or ultrasound scan, or complete blood workup.

Treatment Options

If your cat is found to have GI lymphoma, the most likely treatment will be chemotherapy. Lymphoma is one of the most responsive cancers to chemotherapy, so that is a good front line option. Some cats may experience side effects like nausea and vomiting, but cats generally tolerate chemotherapy much better than humans, and many may show no signs of being on the drugs at all.

Rarely, tumors may grow to a size that causes an obstruction in the GI tract. This is a potentially life-threatening condition the requires immediate surgical intervention. Surgery is generally followed up by chemotherapy, as outlined above.


If left untreated, feline lymphoma can cause death within a matter of four to six weeks, making it vital to receive a diagnosis early and begin treatment immediately. If treatment is begun promptly, remission rates are very high. Generally, however, even cats who responded favorably to chemotherapy will experience relapse within a year of the initial diagnosis. Chemotherapy the second time around is far less effective, and care will typically be focused on making the cat as comfortable as possible. Few cats live longer than 14 or 15 months after their diagnosis.

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