The Pet Tree House - Where Pets Are Family Too : Lymphoma in Cats

Sunday, August 17, 2014

Lymphoma in Cats

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.

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 legs.

How is lymphoma in cats diagnosed?
Diagnosis of lymphoma in cats is based on results of a physical examination and microscopic examination of biopsies or cells taken from affected tissues. This will not only confirm the diagnosis, but help to determine how aggressive the cancer may be, and provide a basis for treatment and prognosis. A complete blood count, serum chemistry, urinalysis, radiographs (X-rays), and/or ultrasound examinations are generally performed to assess the health of the cat and determine which organ systems may be involved. Testing for FeLV and FIV may reveal that a cat is positive for one or both of these diseases, which will affect the prognosis. A PCR for Antigen Receptor Rearrangement (PARR) test can help differentiate lymphoma from other diseases. Examination of samples taken from the bone marrow may also be indicated in some cases.

How is lymphoma in cats treated?
Treatment for feline lymphoma usually consists of chemotherapy. In almost all cases a combination of different drugs is given over the course of many weeks. These drugs may include chlorambucil, doxorubicin, cyclophosphamide, vincristine, L-asparginase and prednisolone or prednisone. In some cases, such as cats with nasal lymphoma, radiation therapy may also be used. In general, cats tolerate chemotherapy very well. If side effects become severe, the treatment protocol can be modified to decrease the effects.

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.

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