Lymphoma (cancer that originates in the
lymphocytes, a type of white blood cell) is one of the more common cancers in
cats. Male cats, and cats in the Northeast in general,
have an increased risk-probably related to an increased risk of feline leukemia virus. Cats who test
positive for FeLV have a 60-fold increased risk of developing lymphoma, while
cats who are positive for feline immunodeficiency virus
(FIV) have a 5-fold increased risk for developing this type of cancer. Cats who
are positive for both viruses have an 80-fold increase in their risk of
developing lymphoma. Whether these viruses have a direct effect in causing the
cancer or act primarily by interfering with the cat’s normal immunity is not
known for certain.
The most common lymphoma sites in cats are the gastrointestinal system, the
spine, and the chest cavity. The gastrointestinal type is the most common of
the three forms of lymphoma and is not as closely associated with FeLV as are
the other two. This type appears in older cats as weight loss and a drop in
appetite. Some cats will vomit and/or have diarrhea, depending on the
exact location of the cancer. Stomach cancers tend to cause vomiting and intestinal cancers
are more likely to cause diarrhea. Siamese and domestic shorthairs seem to have
an increased risk of developing this type of lymphoma.
The following information isn’t intended to replace regular
visits to your veterinarian. If you think your cat may have feline infectious
peritonitis, please see your veterinarian immediately. And remember, please do
not give any medication to your pet without talking to your veterinarian
Mediastinal lymphoma occurs in the lymph nodes inside the chest cavity. Cats
under 5 years of age who are FeLV positive are at risk for developing this type
of cancer, especially if they are Siamese or one of the Oriental breeds. Fluid
will build up and leads to difficulty breathing, along with regurgitation and loss of appetite.
Spinal lymphoma tends to show up in 3- to 4-year-old male cats, especially
if they are FeLV positive. The first signs may be problems with their hind
Diagnosing lymphoma usually requires blood tests, including tests for FeLV
and FIV. Chest X-rays help with mediastinal masses and ultrasound can be
helpful for abdominal growths. Spinal growths may require special dye studies,
combined with X-rays or a spinal tap (removing spinal fluid for analysis).
Treatment: Surgery, radiation, and chemotherapy have all been used to treat
lymphomas, depending on the exact location and whether the cancer has spread.
The prognosis is best for a cat with a single intestinal nodule and worst for a
cat with a spinal growth.
WebMD Veterinary Reference from "Cat Owner's Home Veterinary Handbook"