LYMPHOMA IN CATS

Cancer that begins in the cells of your cat’s immune system is referred to as lymphoma in cats. As a result of uncontrolled growth of lymphocytes, which are a type of white blood cell, these abnormal lymphocyte cells accumulate and develop into tumors. While lymphoma can begin to develop anywhere in the body, the sites where it develops most often include the small intestine, the lymph node, the kidney, the liver, or inside the chest cavity.

Although lymphoma can be found in cats of all ages, this condition is far more likely to be identified in middle-aged to older cats. An early diagnosis will allow for early intervention on behalf of the veterinarian, resulting in improved quality of life for the cat. A longer survival time is possible for those animals receiving timely medical care.

Causes

The specific reason for the development of lymphoma in cats can vary; however, several other risk factors are associated with an elevated incidence rate.

Viral infections

Historically, feline leukemia virus (FeLV) was one of the primary causes of lymphoma. While widespread use of Felv vaccinations and screening has decreased the incidence of Felv-induced lymphomas, Felv-infected cats still appear to be at higher risk than non-infected cats. Additionally, while data on this subject are less complete, it appears that infection with feline immunodeficiency virus (FIV) may also increase the incidence of lymphoma in affected cats.

Chronic Inflammation

There is evidence suggesting that long-standing inflammation, particularly gastrointestinal inflammation, increases the risk of developing intestinal lymphoma. Chronic intestinal inflammation, including inflammatory bowel disease may be associated with an increased risk of intestinal lymphoma, although the exact relationship remains under investigation.

Additional Risk Factors

Genetics, age and environmental exposures are likely contributing to the incidence rate of lymphoma in cats; however, these relationships have yet to be clearly defined.

Symptoms

• Weight loss
• Decreased appetite
• Vomiting
• Diarrhea
• Lethargy
• Enlarged lymph nodes
• Difficulty breathing (if the chest is affected)
• Increased thirst or urination in some cases
• Abdominal swelling
• Poor coat condition

Risks and Complications

Untreated lymphoma generally progresses over time, affecting additional tissues and organs depending on the type and location of the disease. Cancerous cells grow and replace functioning cells within an organ, causing nutritional deficiencies, reduced immune function and decreased quality of life.

The type of lymphoma that occurs in the intestine typically results in significant weight loss and dehydration because of decreased nutrient uptake. In cats whose lymphoma has progressed into the chest area, difficulty breathing (due to fluid accumulation or expansion) is typical.

In advanced stages of lymphoma, the liver, kidneys and bone marrow may be impacted, resulting in anemia, weakness and increased susceptibility to infection.

Diagnosis

Determining whether your cat has lymphoma requires a combination of clinical evaluation (physical examination), laboratory evaluation and radiographic (imaging) evaluations.

Your veterinarian will begin evaluating your cat based upon its clinical findings and will perform a physical examination to look for enlarged lymph nodes or abdominal tumors. Laboratory tests will evaluate how well each of your cat’s major organs is functioning and the overall health status of your cat. Testing for feline leukemia virus (FeLV) and feline immunodeficiency virus (FIV) is common.

Radiographic images such as abdominal ultrasounds or chest X-rays will provide your veterinarian the opportunity to view abnormalities in organs or enlarged lymph nodes. Fine needle aspirate sampling, biopsy sampling, or endoscopic sampling of the affected tissue is commonly required to confirm the diagnosis. Additional testing will likely occur to assist in determining the extent of the disease and create a treatment plan.

Treatment

Treatment will depend on the specific characteristics of the cancer (the type, where it is located and how far it has grown), as well as the general health status of the cat.

Chemotherapy

The majority of feline lymphomas are treated using chemotherapy. Cats generally tolerate chemotherapy better than humans and severe side effects are less common. achieving remission, meaning clinical signs and detectable cancer are reduced or temporarily controlled.

Surgery and Radiation Therapy

If the lymphoma is localized (limited to one area), surgery may be indicated. Surgery may be considered in selected cases, particularly when lymphoma causes an intestinal mass or obstruction. However, there are limited indications for radiation therapy in cats. These would primarily involve palliative treatment of localized tumor masses or when used concurrently with chemotherapy.

Supportive Care

While supportive care cannot cure your pet’s lymphoma, these therapies can greatly improve the quality of their lives during the treatment process. Nutritional support, anti-nausea medications, pain management, appetite stimulants and intravenous fluid therapy can help alleviate systemic symptoms associated with lymphoma.

It is essential to schedule regular follow-up appointments so your veterinarian can evaluate your pet’s response to the treatments being administered and make adjustments to the treatment regimen accordingly.

Prevention

Unfortunately, it is difficult to eliminate the risk of developing feline lymphoma. There are, however, several strategies that can help reduce your cat’s risk of developing lymphoma:

Indoor housing reduces your cat’s contact with viruses (such as FeLV), which can cause lymphoma. All cats should receive vaccinations against FeLV and all cats should undergo periodic testing for FeLV, particularly those that spend extended periods outside or live in households with other cats that are positive for FeLV.

Your veterinarian can examine your cat regularly to detect any potential health problems before they become significant and to investigate any unusual changes (i.e., unexplained weight loss, persistent vomiting or diarrhea).