Our veterinarians in Turlock often encounter cats with lymphoma, a type of cancer that affects specific white blood cells in the cat's body called lymphocytes. In this post, we'll discuss the different types of lymphoma that can affect cats, how they are diagnosed, and the various treatment options available to them.
What is lymphoma in cats?
This cancer affects a cat's immune system's lymphocytes, which move through the body in blood and lymphatic vessels. It is associated with the feline leukemia virus.
What causes lymphoma in cats?
Feline leukemia virus (FeLV) and feline immunodeficiency virus (FIV) are two viruses that commonly cause lymphoma in cats. However, the good news is that more cats are getting vaccinated against feline leukemia as part of their annual wellness and vaccination care. This has resulted in decreasing rates of feline leukemia and lymphoma. Nonetheless, there is still a long way to go in terms of improving the situation. Lymphoma is responsible for about 30% of all cancers diagnosed in cats.
Apart from vaccination, avoiding contact with FeLV or FIV-infected cats and staying away from smoke can help prevent lymphoma in cats. It's also important to detect the disease early, as this can significantly improve a cat's chances of survival.
Where is lymphoma typically found in cats?
Lymphoma can develop in multiple organs since lymphocytes are found throughout your cat's body.
The disease is commonly found in a cat's nasal cavity, mediastinal tract, or gastrointestinal tract. The location of the disease and the size of the lymphocytes (either small cells or large cells) will determine how your cat's lymphoma is classified.
- Renal lymphoma is also associated with feline leukemia. This type of lymphoma impacts a cat's kidneys and may lead to kidney failure.
- Intestinal lymphoma is the most common form of lymphoma in cats. Found in the GI tract, this cancer is most often seen in cats over 9 years of age.
- Mediastinal lymphoma affects the lymphoid organs found in a cat's chest. These organs include the lymph nodes and the thymus. This type of lymphoma is typically found in cats around 5 years of age and is strongly associated with feline leukemia.
What are the most common symptoms of lymphoma in cats?
When it comes to lymphoma in cats, symptoms will depend on where the cancer is located.
Diarrhea, vomiting, and weight loss are common in cats with intestinal lymphoma. These symptoms occur very rapidly—often in just a matter of days or weeks—in cats with large-cell intestinal lymphoma. Cats with small-cell intestinal lymphoma experience a much slower onset of symptoms.
Mediastinal lymphoma is a type of cancer found in a cat's chest area, which can cause difficulty in breathing. The tumor may also cause fluid accumulation around it, which further worsens breathing difficulties in cats. On the other hand, renal lymphoma in cats can lead to a buildup of toxins in their blood system, causing symptoms similar to kidney failure such as reduced appetite,
increased thirst, and vomiting. Additionally, the cat's nervous system may also be affected, leading to symptoms such as unstable gait, behavior changes, and seizures.
Feline Lymphoma Stages
There are five stages of feline lymphoma (I to V). There are substages within each period where a cat either does or doesn't show sickness symptoms.
Stage 1 - Cancer cells are only present in a single lymph node.
Stage 2 - Cancer cells start to appear in more than one lymph node, but the cancer remains within the same area of the body.
Stage 3 - Cancer cells develop in lymph nodes throughout the body.
Stages 4 & 5 - The cancer cells affect specific body parts. In Stage 5, cancer cells appear in the spleen and/or liver. In the final stage, cancer cells reach the bone marrow and/or other tissue (in addition to the ones previously listed).
How is lymphoma in cats diagnosed?
Depending on the extent of the disease and the location, either fine needle aspiration cytology or a biopsy will typically be used to diagnose lymphoma in cats.
In some cases, vets may require sampling of bone marrow or other organs, or molecular testing on tissues or blood in order to provide a definitive diagnosis of lymphoma.
Diagnostics may also include:
- Bloodwork such as CBC (Complete Blood Count) and full chemistry panel
- Testing for feline leukemia FeLV/FIV
- Urinalysis
- Ultrasound imaging to evaluate the cat's GI tract, spleen, liver and lymph nodes
- X-rays to evaluate lungs and lymph nodes
Can lymphoma be misdiagnosed in cats?
Lymphoma misdiagnosis can happen in cats, as it is not always easy to diagnose without additional testing. Besides, there are plenty of other conditions that can cause similar symptoms. Therefore, many cats may not receive a definite lymphoma diagnosis. The diagnostic tools and tests mentioned above can help identify the disease.
What is the treatment for lymphoma in cats?
Chemotherapy is the primary treatment for cats diagnosed with lymphoma, although radiation can also be an option. Surgery (with or without chemo) may be recommended if the lymphoma is confined to a single area, such as the cat's nasal area or abdomen.
If, for any reason, chemotherapy is not an option, prednisone may be prescribed as palliative or hospice care.
What is the prognosis for cats diagnosed with lymphoma?
Cats diagnosed with gastrointestinal large cell lymphoma have a prognosis of about 6-9 months with treatment. Only a small percentage of cats that reach full remission with treatment can live up to 2 years, which is quite rare.
On the other hand, cats diagnosed with small cell gastrointestinal lymphoma may live up to 2-3 years with the disease, provided they receive ongoing care with oral medications.
Unfortunately, cats diagnosed with mediastinal lymphoma and feline leukemia face a poor prognosis of about 3 months. However, cats that do not have feline leukemia and are diagnosed with mediastinal lymphoma may show a full or partial response to chemotherapy. These cats have an average survival time of about 9-12 months.
Unfortunately, renal lymphoma has a very poor prognosis. The average survival rate for this type of lymphoma is only 3-6 months, though there are isolated reports of cats surviving far longer. Renal lymphoma tends to spread to the brain and central nervous system, which occurs in approximately 40% of renal lymphoma cases and worsens the prognosis for this disease.
If not treated with chemotherapy, large cell lymphoma in cats will progress very quickly and soon be fatal. Palliative treatments may help extend the cat's quality of life by a few weeks or months.
Note: The advice provided in this post is intended for informational purposes and does not constitute medical advice regarding pets. For an accurate diagnosis of your pet's condition, please make an appointment with your vet.