Symptoms & Treatment of Lymphoma in Cats

Sadly, cancer impacts countless human lives. And our pets, as well, are getting cancer at an astonishing rate. One in four dogs will get a neoplasia (cancer growth) at some time in their lives. And one in five cats will develop cancer at some point in their life, with cats more likely to die from cancer than any other disease, particularly older cats.

young woman professional veterinarian strokes a big gray cat on table in veterinary clinic.
credit: Kateryna Kukota/iStock/GettyImages

Feline lymphosarcoma, commonly known as lymphoma or LSA, is a type of blood cancer and accounts for nearly 30% of newly diagnosed cancers in cats, reports VCA Hospitals. And it's the most common cancer affecting cats. So, if your beloved cat is diagnosed with lymphoma, it's devastating news. But be encouraged by compelling evidence that supports the role of chemotherapy in reducing the impact of lymphoma on your cat.

What is lymphoma?

Lymphoma is a cancer of the lymphocytes, the white blood cells found in the lymph nodes. Among the many important roles these extraordinary cells perform in the immune system is the production of antibodies and other substances that fight foreign proteins and disease organisms, thus fighting infection and keeping a cat in optimal health.

Because lymphocytes travel throughout the body in the bloodstream and a network of lymphatic tissue, nodes, and vessels in their normal productive capacity, lymphoma can affect multiple organs anywhere in the body, and is therefore known as systemic rather than localized (cancer where tumors metastasize on organs). Consequently, when a tumor is removed in cats who have only a single site lymphoma, the cancer is not gone.

Doctor veterinarian at clinic.
credit: Vasyl Dolmatov/iStock/GettyImages

Categorized by its location in the body, there are several types of lymphoma, with the three most common forms as follows:

  • Mediastinal: This form of lymphoma affects lymphoid organs in the chest, such as the thymus and associated lymph nodes. Often seen in young cats, the onset of mediastinal lymphoma is about 5 years old and clearly linked to the feline leukemia virus. About 80% of diagnosed cases, test positive for

    FeLV. At the same time, mediastinal lymphoma is also seen in cats that are not affected by the virus, especially older cats.

  • Alimentary: This form of lymphoma affects the gastrointestinal or digestive tract and surrounding lymph nodes. Least likely to be associated with feline leukemia_,_ intestinal lymphoma is the most common form of LSA in cats. Senior cats between the ages of 9 and 13 are more commonly seen with this lymphoma.

  • Multicentric: Involving multiple lymph nodes and often multiple organs, for example, the kidneys or liver, this form of lymphoma is directly associated with feline leukemia, and if the cat is FeLV positive, the prognosis is poor.

Causes of lymphoma

When the white blood cells, which fight off infection in a cat's body, proliferate uncontrollably it leads to lymphoma. In the past, feline leukemia virus was the leading cause of lymphoma in cats, and typically young cats between the ages of 2 and 6 were affected. This still occurs but is less prevalent. With advancing veterinary technology and vaccines available for FeLV, nowadays, LSA is generally affecting older cats and in various forms.

Feline aids virus may also play a role in a cat developing lymphoma. The statistics show that FIV increases the risk of a cat developing lymphoma six times over a non-FIV-infected cat.

Evidence does not support a genetic component to LSA; therefore, any breed of cat is susceptible to the disease.

Vet With Cute Cat
credit: FatCamera/iStock/GettyImages

Theories suggest that lymphoma is possibly linked to long-standing inflammatory disease. Also, environmental exposure to smoke, as in second-hand cigarette smoke, has been found to increase a cat's risk of LSA.

Symptoms of feline lymphoma

Due to the diversity of lymphosarcoma's anatomical sites, symptoms range according to which organ is affected. The following symptoms are for key sites, as follows:

  • Intestinal or alimentary feline lymphoma is the most common LSA and symptoms are similar to other intestinal diseases say VCA Hospitals. Clinical signs include *vomiting, diarrhea, weight loss, loss of or a decrease or even increase in appetite, or a combination of these symptoms. *
  • Mediastinal lymphoma affecting the chest cavity is often associated with signs of respiratory difficulty. Fluid tends to accumulate around the tumor, which does not permit an affected cat to inflate the lungs.
  • Renal lymphoma, part of the multicentric or multi-systemic form of lymphoma and affecting the kidneys presents with signs associated with kidney failure, such as decreased appetite, increased thirst, weight loss, and vomiting due to a buildup of toxins in the bloodstream which the kidneys cannot effectively filter when affected by lymphoma.

Diagnosis of feline lymphoma

Upon performing blood work, your veterinarian will rule out other conditions that present with the same or similar clinical symptoms as lymphoma. As an alternative to surgical biopsy, many vets perform a fine needle aspiration of an enlarged kidney or lymph node, fluid in the chest, or thickened portion of an intestine removing cells that are then examined under a microscope. If this test is inconclusive, a surgical biopsy must be performed.

A definitive diagnosis of lymphoma requires finding cancerous cells.

A biopsy can also determine whether the lymphoma is high-grade, which is fast-growing and more malignant, versus low-grade, which means your cat will most likely respond to chemotherapy treatment with longer periods of remission.

Treatment protocol for lymphoma

One of a number of injectable chemotherapy protocols are generally used to treat high-grade (large cell) lymphomas, whereas low-grade (small cell) lymphomas are treated with the steroid prednisone and chlorambucil, an oral chemotherapy agent. If your cat is affected by lymphoma, it may be a comfort to know that, unlike in humans, most cats tolerate chemotherapy very well and rarely lose their hair or get sick. Only 10% of cats experience side effects like vomiting, diarrhea, and decreased appetite.

Veterinarian examining cat in vet's surgery
credit: Robert Daly/Caiaimage/GettyImages

Prognosis of feline lymphoma

Dependent upon many factors, such as the location of the lymphoma, the cat's age, presence of the feline leukemia virus, and other variables, the prognosis of lymphoma is different in every case.

But thanks to early recognition through the owner's awareness and observation of symptoms, prompt veterinary diagnosis, and technologically advanced treatment protocols, cats do, indeed, have a substantially better chance of surviving cancer today compared to several years ago. In fact, 75% of cats respond to chemotherapy treatment and go into remission. That means, not only living longer — but living longer with a good quality of life. After all, quality of life is the key objective when treating a cat for lymphoma or any cancer.