Lymphosarcoma (Lymphoma) in Cats

Overview of Feline Lymphosarcoma (Lymphoma)

Lymphosarcoma (lymphoma) is a malignant cancer that involves the lymphoid system. In a healthy animal, the lymphoid system is an important part of the body’s immune system defense against infectious agents such as viruses and bacteria. Lymphoid tissue normally is found in many different parts of the body including lymph nodes, liver, spleen, gastrointestinal tract and skin.

Classification of Lymphosarcoma in Cats

Lymphosarcoma is classified according to the location in the body in which the cancer begins.

These include:

Currently in the USA, gastrointestinal lymphoma is the most common form. Historically, mediastinal lymphosarcoma occurred most frequently in young cats infected with feline leukemia virus, but reports of young cats with FeLV positive lymphoma are less common than in the early 1980’s. These cats may have involvement in other areas of the body, such as the bone marrow. The gastrointestinal form of lymphosarcoma most commonly affects older cats that are not infected with the feline leukemia virus.

Recently, research has shown that cats that live in smoking environments are 2 to 4 times more likely to develop lymphoma than cats that live in smoke-free environments. The exact mechanism is not understood.

Lymphosarcoma occurs in middle-aged to older cats. No breed of cat is known to be at a higher risk for lymphosarcoma than other breeds. Males and females of both species are affected equally. Infections with both feline leukemia virus (FeLV) and feline immunodeficiency virus (FIV) have been shown to increase the risk of developing lymphosarcoma. Cats infected with FeLV often develop lymphosarcoma at a young age.

Symptoms in cats with lymphosarcoma depend primarily on the location of the tumor cells. Symptoms include enlargement of external lymph nodes, vomiting, diarrhea, loss of appetite, weight loss, lethargy, difficulty breathing and increased thirst or urinations. Cutaneous lymphosarcoma can cause redness or flakiness of the skin, ulceration (especially near the lips and on the footpads), itchiness (pruritus) or lumps in the skin.

Diagnosis of Lymphosarcoma (Lymphoma) in Cats

Diagnostic tests are needed to identify lymphosarcoma and exclude other diseases. These tests may include:

Treatment of Lymphosarcoma (Lymphoma) in Cats

Home Care

Seek veterinary care promptly if you detect lumps below your pet’s skin in the neck, shoulders, armpits, or back legs or if your pet has vague symptoms of illness such as loss of appetite, lethargy, and weight loss. Watch your pet for vomiting, diarrhea and development of infections.

Preventive Care

The best prevention is to avoid infection of cats with FeLV and FIV by limiting their exposure to other cats of unknown status. Also, smokers should consider quitting smoking or only smoking outside.

In-depth Information on Lymphosarcoma (Lymphoma) in Cats

Other diseases can mimic the signs of lymphoma. Some of these may include:

Other diseases that cause enlargement of the lymph nodes may include:

Other diseases that can vomiting, diarrhea, weight loss, decreased appetite include:

Other diseases that can cause difficulty breathing may include:

Veterinary care should include diagnostic tests and subsequent treatment recommendations.

Diagnosis In-depth

Diagnostic tests are needed to recognize lymphosarcoma and exclude other diseases. Tests may include:

Therapy In-Depth

Treatment for lymphosarcoma may include one or more of the following:

Depending upon the drug, treatment can be given by injection under the skin (subcutaneously), intravenously or by mouth (orally). Combinations of these drugs work better than a single drug.

A protocol is an outline of the treatment plan consisting of:

Several different protocols have been used to treat lymphosarcoma and actual treatment may vary from veterinarian to veterinarian. In addition, adjustments to the protocol may be made depending upon the patient.

The most common adverse effects of cancer chemotherapy are gastrointestinal symptoms (e.g., loss of appetite, vomiting, diarrhea) or a decreased white blood cell count, which may increase the risk of secondary infection. Cats generally do not experience the hair loss that affects humans undergoing chemotherapy. In fact, cats usually tolerate chemotherapy much better than do humans. The risk of a serious adverse effect that would require hospitalization is small (perhaps 5 to 10 percent). If adverse effects do occur, your veterinarian may change the protocol to prevent these adverse effects during future treatments.

Fifty to sixty percent of treated cats achieve remission with an average survival time of 6 to 8 months. Ten to fifteen percent of cats treated for lymphosarcoma survive 2 years or more.

It often is possible to treat pets successfully a second time using different drugs or radiation therapy when relapse occurs. Different treatment approaches are necessary because the malignant lymphocytes have become resistant to the drugs used previously. It is more difficult to treat animals experiencing a second or third relapse and remission times generally are shorter.

In some circumstances, radiation therapy may be recommended in addition to or instead of chemotherapy. Radiation therapy requires referral to a specialty institution that offers radiation therapy because it requires specialized equipment and training.

Radiation therapy may be recommended if the pet has lymphosarcoma localized to a single site. It is essential, in this situation, to conduct a thorough search for other areas of involvement. Chemotherapy should be used in conjunction with radiation therapy if other areas of involvement are suspected or if a cat with lymphosarcoma is infected with FeLV or FIV. A full course of radiation involves a total of 10 to 16 treatments given 3 to 5 times a week. Adverse effects vary depending upon the region of the body treated and the number of treatments given. Animals must anesthetized for each treatment to prevent movement during radiation exposure.

Radiation can be used if lymphosarcoma is causing in a specific location of the body is discomfort or clinical signs. This type of treatment is called palliative radiation therapy, and involves use of a few large doses of radiation to the affected area. Adverse effects usually are minimal with this type of radiation therapy.

Surgery rarely is used in the treatment of lymphosarcoma, and is more commonly used to make a diagnosis of lymphosarcoma (to obtain biopsy specimens for examination by a veterinary pathologist).

Follow-up Care for Cats with Lymphoma