What’s the Difference? Feline Leukemia Virus and Feline Lymphoma Types

November 28, 2022
Learning the difference between feline leukemia virus and feline lymphoma

Receiving a diagnosis that your precious kitten developed lymphoma is not a great feeling. Many questions come up with that discovery, and sometimes not all of them arrive when you have your vet available to answer them. This post will shed some light on what that lymphoma diagnosis means, and hopefully answer some of those naturally arising questions.

What is feline lymphoma?

Lymphoma is a systemic cancer that affects cells in the immune system. The affected cells are called lymphocytes which circulate throughout the body, making lymphoma a systemic cancer. 

Lymphocytes interact with many different locations in the body including the thymus gland, the spleen, bone marrow, and tissues in the stomach. Anywhere within the body that works to defend against incoming threats interacts with these cells in some form. Lymphoma can be present  differently depending on the individual case but the most commonly diagnosed form is that of the gastrointestinal tract, making up 50-70% of all feline lymphoma cases. There is also Mediastinal lymphoma, as well as Renal lymphoma, which both have a correlation with the feline leukemia virus.1

While lymphoma is still one of the most commonly diagnosed cancers in cats, making up around 30% of all feline cancer diagnoses, it is less common than it has been in the past due to its connection with the feline leukemia virus and the increase in vaccines used to prevent it. 

Different types of feline lymphoma 

The common types of lymphoma all affect the body in different ways. 

Gastrointestinal lymphoma 

This is the most common form, and it primarily affects senior cats aged 9 to 13.The initial signs that your cat may have developed gastrointestinal lymphoma would be a change in appetite, weight loss, vomiting, or diarrhea. All these signs should prompt a pet parent to bring their kitten in for a check up to see what’s going on.1 

When a veterinarian examines a cat with these symptoms, they will perform some tests, usually bloodwork, and sometimes an ultrasound of the intestinal tract. However, the difficulty with diagnosing this form of lymphoma comes from the fact that the same symptoms and initial test results are also commonly seen in cats with Inflammatory Bowel Disease, which can be a setback in finding the correct treatment in some cases. 

The last step to diagnose this form of lymphoma is to perform an intestinal biopsy, either through endoscopy—the use of a flexible camera to view the stomach and intestines—or by taking small samples through surgery. 

Intestines can develop in both Small cell and Large cell lymphomas. Small cell lymphomas are typically considered indolent, meaning that they are less aggressive than other cancers. Large cell lymphomas are much more aggressive and often come with a worse prognosis; they are also typically associated with a mass in the intestines.2,3 

Mediastinal lymphoma 

This lymphoma develops in the chest cavity, often in the lymph nodes or the thymus gland (a gland that produces and trains T-cells to work with the immune system). This form of lymphoma affects younger cats most often, with patients being on average 5 years old when first diagnosed.1 

Symptoms of this type of lymphoma include difficulty breathing and other respiratory issues. Fluid can also develop around the affected area in the chest, leading to a very poor prognosis compared to other lymphoma types. 

Cats that are at risk of lymphoma can be given the feline leukemia virus (FeLV) vaccine to help reduce the likelihood of future occurrence, but aside from addressing it early on, the only treatment that is currently known to show at least a partial response is chemotherapy in cats that do not also have FeLV. Though with how closely mediastinal lymphoma and FeLV are linked, these cases are not the most common, with about 80% of all mediastinal lymphoma cases also testing positive for FeLV.2,3 

Renal lymphoma 

Another common location for lymphoma to develop in cats is in the kidneys. Similar to mediastinal lymphoma, this cancer is linked to FeLV, with about 50% of cases also testing positive for the virus.1 

Symptoms of renal lymphoma are closely correlated to signs of kidney failure. These often include decreased appetite, weight loss, increased thirst, and vomiting. Because cells in the kidney are no longer performing their functions to protect the body from toxins, the body begins to show signs that those toxins are accumulating in the bloodstream.2

Unfortunately, renal lymphoma has a poor prognosis as well. The average survival for this type of lymphoma has regularly been reported to be 3-6 months, with some outliers of cats surviving for a significantly longer time. The poor prognosis stems from renal lymphoma’s tendency to spread to the brain and central nervous system, which occurs in approximately 40% of all cases of renal lymphoma.3 

Feline Leukemia Virus (FeLV)

The FeLV is one of the most common infectious diseases in cats, as it can be spread easily from cat to cat through saliva, nasal secretions, urine, feces, and a mother cat’s milk. Given the nature of cats, the virus is able to travel with almost no notice to pet parents, through bites, or mutual grooming, shared litter boxes, and feeding dishes. The virus can also last up to a couple of hours outside of a cat’s body in average household conditions, leading to it being able to create quite an impact on multiple cats in a household, or outdoor cats to one another.4,5 

This virus is a catalyst to many forms of cancer, blood disorders, and immune deficiencies. And in many cases, it’s common for cats not to show any signs of disease early on in their infection. but for their health to deteriorate over time, leading to cycles of health and sickness. Symptoms at that point in the infection include loss of appetite, weight loss, poor coat condition, enlarged lymph nodes (often a sign of lymphoma), persistent fever, pale gums, diarrhea, neurological disorders (such as seizures), skin or urinary tract infections, and reproductive failures. 

Thankfully, due to the commonness of the virus, vaccines have been developed to help prevent cats from catching and spreading the virus and limiting the number of cases. While it still affects a large population of cats—2-3% of cats in the United States being diagnosed with it—that amount has the constant potential to lower as more cats are vaccinated against it. And with more pet parents becoming educated about the virus and taking steps to limit the opportunities for exposure from other cats, that number can continue to go down.4,5 

Talk to your vet about the feline leukemia virus vaccine. 

ImpriMed is working hard to offer pet parents support with feline lymphoma 

ImpriMed has successfully developed a system that helps dogs with canine lymphoma, and is now working hard to build up that same system for cats, but  needs help to get enough data to offer effective help to cat parents out there. 

ImpriMed is conducting a study on feline cancer cells and are happy to offer free immunophenotyping for your pet. Immunophenotyping is one of the first steps your vet takes to find the best treatment option for your pet. It’s the process that determines what type of cells are affected and leads your vet to make the right choices for your cat’s treatment. 

And it will help us to be able to help even more cats in the near future. 

Find out more about our Free Immunoprofile for feline lymphoma and leukemia

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