Lymphoma in Cats

As cats get older, they are more likely to be affected by certain types of cancer. Lymphoma is one of the most common forms of cancer in cats, most often seen in middle-aged and senior cats. Unlike some forms of cancer, feline lymphoma is equally likely to affect male and female cats of all breeds. This blog will look at the different types of lymphoma in cats, along with the causes, symptoms and treatments available. Receiving a diagnosis of lymphoma for your cat can be incredibly distressing. However, if spotted early, there are effective treatments available that can result in remission for many cats.

What is Feline Lymphoma?

Feline lymphoma is a malignant (aggressive) cancer of the lymphatic system, which is a network of vessels, tissues and organs that forms part of the immune system. The lymphatic system interacts with every part of the body, so lymphoma can affect lots of different areas.

Lymphoma in cats can be classified according to which part of the body it affects. For example:

  • Alimentary lymphoma: This is the most common kind of lymphoma in cats, making up 70% of cases. It affects the gastrointestinal (digestive) tract.
  • Multicentric lymphoma: Less commonly, lymphoma affects multiple lymph nodes and lymphatic centres, often including the spleen and liver.
  • Mediastinal lymphoma affects the lymph tissue in the chest.
  • Renal lymphoma affects the kidneys.
  • Nasal lymphoma affects the nasal passages in the nose
  • Spinal lymphoma affects the spine.

Lymphoma in cats can also differ in terms of the specific types of cells that are affected. There are two types: B-cell lymphoma, which makes up 70% of cases, and T-cell lymphoma.

Depending on which type of lymphoma your cat is diagnosed with, treatment will differ.

What Causes Lymphoma in Cats?

Before widespread vaccination became commonplace, feline leukaemia virus (FeLV) was a key cause of lymphoma in cats. This is an infection that affects white blood cells and bone marrow in cats, weakening the immune system. However, this is now uncommon as most pet cats are vaccinated against this.

Inhaling second-hand smoke from cigarettes is also thought to increase a cat’s risk of developing lymphoma.

What are the Symptoms of Lymphoma in Cats?

Symptoms of the most common type of lymphoma in cats, alimentary lymphoma, include:

  • Weight loss
  • Loss of appetite
  • Lethargy
  • Vomiting
  • Diarrhoea
  • Abdominal swelling
  • Lump
  • Increased thickness of the intestinal loops (this can be felt upon examination by a vet)

Cats with other forms of lymphoma may suffer from other symptoms, depending on the type of lymphoma and location in the body.

Cats with multicentric lymphoma will often develop painless swelling around the lymph nodes. These are located throughout the body, but are most visible under the angle of the jaw, in front of the shoulders, and at the back of the knees.

A cat with mediastinal lymphoma may suffer from breathing difficulties. This is because the lungs have less space than normal as a result of the cancer in their chest. There are often effusions (increased fluid) surrounding the lungs too.

Symptoms of renal lymphoma include increased thirst and urination. Cats with renal lymphoma often seem very unwell, and examination by a vet often reveals swollen kidneys.

Cats with nasal lymphoma often experience sneezing, runny eyes and sometimes nose bleeds.

Spinal lymphoma can cause weakness or paralysis of the back legs.

How do Vets Diagnose Lymphoma in Cats?

There are a range of different tests that can be carried out to find out if a cat has lymphoma. Usually, cats will need to undergo more than one of the following tests to reach a full understanding of the cancer, including how it is likely to develop.

Blood Tests

If a cat is suspected of having lymphoma, the very first step is to carry out full blood tests. This will allow vets to check for feline leukaemia virus and feline immunodeficiency virus, as well as take a look at your cat’s red and white blood cells.

Ultrasounds

Ultrasound imaging can be used to look at your cat’s kidneys and gastrointestinal tract. Your vet will likely recommend this for your cat if they suspect renal or alimentary lymphoma.

While ultrasound can strongly suggest a diagnosis of alimentary lymphoma, it is not conclusive. This is because some conditions like inflammatory bowel disease may cause the same visual changes, such as thickened intestines.

Biopsy sample

Taking a tissue sample and sending it off for analysis is the best way to get a definitive diagnosis of lymphoma in cats. This involves sedation, so your vet will discuss the risks associated with this and advise you on whether they recommend it.

Surgery

In cases of multicentric lymphoma, a lymph node is often removed in its entirety and submitted to the lab for analysis.

Fine Needle Aspirate

If the affected area is accessible, your vet may take a small sample of cells using a needle.

Depending on the patient, this can often be done quickly and easily during a consultation. However, this does depend on the individual cat and the site that is being sampled. For example, some cats may find it very stressful to have cells taken from the kidney or chest cavity, and if they are fighting the process, it can affect the quality of the sample. In these cases, sedation is required.

Unfortunately, this technique is not always enough to reach a diagnosis.

Treatment

Lymphoma is a systemic form of cancer, which means the cancer cells are spread throughout the body. Therefore, the whole body needs to be treated. This is done using chemotherapy.

Chemotherapy can be administered in a number of ways, and can either involve one drug, or a combination of different ones. Usually, chemotherapy used to treat lymphoma involves a combination of injections in the clinic, and tablets given at home.

The frequency of injections might start as often as every week, and reduce as your cat responds to the treatment. Chemotherapy for lymphoma in cats can last anywhere from 4-18 months.

Your vet will be able to discuss the specifics of your cat’s lymphoma treatment with you, and help you to consider all the available options.

Diets for Cats with Cancer

To support your cat through their illness, your vet may recommend a different food. Hill’s Prescription Diet ON-Care is an example of a cat food designed specifically to help nourish and support cats fighting serious illness, helping to maintain strength and energy as well as encourage a healthy appetite. Speak to your vet to see if your cat would benefit from an ON-Care diet.

Wrapping Up

For any loving cat owner, a diagnosis of feline lymphoma can be heartbreaking. Spotting the symptoms early on is important for giving your cat the best chance at remission. Unfortunately, many cats are not diagnosed until they are very unwell, so always get your cat checked out at the vets if you have any concerns, no matter how small. With full, multi-drug, chemotherapy treatment, up to 70% of cats can respond positively. And while some cats do not respond at all to treatment, most will improve for at least a short time.

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