Gastrointestinal lymphoma is the most common type of lymphoma in cats. Although the cause is unknown there is some evidence that it may be associated with chronic intestinal inflammation and a genetic predisposition. It is most often seen in middle age to older cats. The clinical signs produced are chronic and progressive. They may include one or more of the following signs: vomiting with or without hair, diarrhea, and progressive decrease of appetite and weight loss. Some of the conditions that may produce similar signs are: inflammatory bowel disease (IBD), dietary intolerance, fungal enteritis and other types of intestinal cancers. The following tests may be needed to for diagnosis and treatment:

1. Feline Leukemia and FIV test
2. Fecal examination
3. Complete Blood Count
4. Comprehensive metabolic profile with thyroid level
5. Coagulation testing
6. Cobalamin (B-12) and folate (B-9) testing (serum concentration of both of these vitamins are affected by intestinal absorption)
7. Pancreatic testing
8. Histoplasma antigen testing
9. Radiographs or ultrasound examination

If the above tests do not result in a diagnosis, a biopsy may be scheduled. Diagnosis of intestinal lymphoma as well as inflammatory bowel disease is based on biopsy, and generally biopsies are collected from several sites in the gastrointestinal tract as well as associated lymph nodes and other abdominal organs. After the samples are collected, the pathologist will conduct multiple tests to determine exactly what types of cells are present. This is extremely important because the prognosis and treatment plan is based on this information. These tests help to differentiate IBD from lymphoma and B-cell from T-cell lymphoma. B-cell lymphoma usually presents with a mass-like lesion and has a poorer prognosis than T-cell.

Lymphoma is a systemic disease and requires chemotherapy. For cats with many types of lymphoma, a treatment protocol is designed by an oncologist and usually involves at least four different types of medication that are given for many weeks. There is a group of cats that have low grade T-cell intestinal lymphoma that are best treated with a less aggressive form of chemotherapy involving two medications that can be given orally at home. Cats with this form of lymphoma tend to enjoy long remissions of approximately two years.

Regardless of the type of chemotherapy prescribed, monitoring is essential. Many of the medications used can suppress the cat’s bone marrow and produce low white blood cell counts and anemia. Most patients have medical progress examinations every one to four weeks, and complete blood cell counts are done at the time of the visit. The dosage of medication is adjusted based on the test results and the physical examination. Medication is generally given for the life of the cat. Treatment of these patients can be rewarding and their quality of life excellent.