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My Cat's Lymphocytes are High

Matthew Nesbitt
By Matthew Nesbitt, Journalist specialized in animal research. Updated: January 16, 2020
My Cat's Lymphocytes are High

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Not all symptoms of disease in cats are as obvious as each other. A cat may be seriously ill without showing any signs for a long time. Unfortunately, it is often the medical conditions which don't have obvious symptoms which can be the most-life threatening. A high lymphocyte count is something which can only be determined after a blood test by a qualified veterinary medical professional. While there are different reasons why your cat's lymphocyte count is high, perhaps the most worrying is lymphoma, a type of blood cancer.

In this AnimalWised article on my cat's lymphocyte count is high, we look at the different causes of this symptom, how lymphoma in cats manifests itself and what possible treatment options are available.

You may also be interested in: High Creatinine Levels in Cats
  1. Why is my cat's lymphocyte count high?
  2. What is lymphoma in cats?
  3. Types of lymphoma in cats
  4. Symptoms of lymphoma in cats
  5. Treatment of lymphoma in cats

Why is my cat's lymphocyte count high?

Lymphocytes are a type of white blood cell, the cells in blood which act to defend the body against disease. There are different types of lymphocytes: T cells, B cells and natural killer cells. All the different types of lymphocyte are important in fighting against various types of infection, tissue damage and disease. They are part of the body's immune response. If there are not sufficient amounts of lymphocytes, the cat is immunosuppressed and vulnerable to numerous health problems.

Conversely, if the cat's lymphocyte count is high, this doesn't mean the cat is super-healthy. On the contrary, the cat is likely suffering from one of the following problems:

  • Infection: since part of the body's immune response involves sending lymphocytes to attack disease causing cells, a higher lymphocyte count might mean an infection is present. The type of infection can be varied, but viral infections commonly result in high lymphocyte counts. Infections include cat flu, hepatitis and even leukemia. Protozoal and bacterial infections can also lead to higher white blood cell counts.

  • Stress: chemical reactions in the brain caused by stress can result in increased levels of lymphocytes. The mechanism of this action is relatively poorly known, but it is believed to be in part caused by adrenaline release.

  • Cancer: the two main types of blood cancer are leukemia and lymphoma. Elevated lymphocytes in cats can be caused by two specific types of leukemia, known as chronic lymphocytic leukemia (CLL) and acute lymphoblastic leukemia (ALL). Chronic lymphocytic leukemia is currently more treatable than acute lymphoblastic leukemia[1][2], but both are life threatening. Feline leukemia is caused by the feline leukemia virus (FeLV) and you can read more about it in our article on leukemia in cats. Lymphoma is the name for a group of different blood cancers, which are related to both the feline leukemia virus and the feline immunodeficiency virus (FIV).

The scientific term for an elevated lymphocyte count is lymphocytosis. There are other causes and complications, but they are comparatively rare in cats.

What is lymphoma in cats?

While lymphocytosis is a high lymphocyte count, lymphoma is more specifically a blood cancer which has a high lymphocyte count as a symptom. It is one of the most common diseases in feline veterinary medicine. It is related to the abnormal production of lymphocytes, but it this is not the direct cause. While they derive their name from being produced in the lymph nodes, they are not only produced there and can be found practically throughout the body.

Feline lymphoma is one of the most common types of cancers in cats. According to an extensive study carried out in Switzerland, the mean average of developing lymphoma in cats is 8.5 years, although it is more frequent in younger cats and being male is a contributing factor[3].

Causes of lymphoma in cats

The causes of any cancer in cats are constantly being evaluated. While we research into human cancers is extensive, the same cannot always be said for cats. Depending on the type of animal, there are two pathologies in felines which are particularly associated with lymphoma. These are:

  • Feline leukemia virus (FeLV)
  • Feline immunodeficiency virus or feline AIDS (FIV)

However, it has been reported that these are not the only factors that can trigger the disease. Many patients may suffer from lymphoma without testing positive for the aforementioned viruses.

Types of lymphoma in cats

As mentioned earlier, lymphoma can appear virtually anywhere in the body. Although it is very much associated with lymph nodes, it is largely classified into groups by its location in the cat's system:

  • Gastrointestinal lymphoma: this is when the lymphoma is located in the cat's digestive system. It can be a focal type of cancer (with one or several tumor growths) or diffuse (responds to a general thickening of the tissue it affects). This type of lymphoma is generally associated with middle-aged and senior cats, approximately 6 to 9 years of age. It is the most frequent type of lymphoma in cats and can also be classified due to its size (small or large). While feline lymphoma is related to the FeLV virus, the occurrence of gastrointestinal lymphoma has increased while FeLV prevalence has decreased[4].

  • Mediastinal lymphoma: this type of lymphoma affects the thymus gland and mediastinal lymph nodes. Due to its location, tumor growth can make both breathing and swallowing difficult for the cat. Generally, this is more common in younger cats of less than 2 years in age. Its prognosis is generally good when detected and treated early.

  • Multicentric lymphoma: this term is used in patients who have tumors in several anatomical structures at the same time. It is a very rare form of lymphoma in cats and is particularly associated with the feline leukemia virus. It most frequently affects cats with 3-5 years of age.

  • Extranodal lymphoma: a more common form of cancer in cats, this type of feline lymphoma is related to anatomical structures not listed above. The skin, nasal cavities, kidneys and entire nervous system are generally most affected. Of all of these areas, the most frequent seems to be the nasal cavities. Signs and symptoms can be varied and unspecific, ranging from excessive nasal discharge and loss of motor function. It usually affects cats from the ages of 5 to 9 years.

It can be difficult to determine what causes any illness in cats, but knowing there is a problem is vital. Our article on how to know if your cat is sick can be helpful. Regardless, taking your cat to the veterinarian as soon as you think there is a problem is imperative.

My Cat's Lymphocytes are High - Types of lymphoma in cats

Symptoms of lymphoma in cats

The signs and symptoms of a cat with lymphoma will vary for different reasons. Two of the most important are the size and location of any related tumors. This is why it is helpful to categorize the symptoms according to lymphoma type:

Symptoms of gastrointestinal of lymphoma in cats

Symptoms of mediastinal lymphoma in cats

Symptoms of extranodal lymphoma in cats

  • Ataxia
  • Generalized nervousness signs
  • Nasal discharge
  • Polyuria (increased urination)

This pathology, besides being quite frequent in felines, is one of the most worrying disease from which your cat can suffer. For this reason, your pet deserves maximum attention as long as possible. Early detection and diagnosis of any disease will increase the chances of being able to cure it.

My Cat's Lymphocytes are High - Symptoms of lymphoma in cats

Treatment of lymphoma in cats

As lymphomas are systemic tumors, chemotherapy is the treatment usually recommended by veterinarians. While there is still insufficient research carried out on chemotherapy effectiveness in cats, positive results have been seen[5]. It should be noted that this procedure has side effects, but they are usually manageable in cats.

The chemotherapy treatment consists of 4 distinct phases:

  • Remission induction
  • Maintenance
  • Consolidation/intensification
  • Referral reinduction

As we have indicated, the person in charge of diagnosis and decision-making when treating the patient is the veterinarian. There are different types of chemotherapy protocol, depending on where the cat is being treated.

Lymphoma in cats: life expectancy

It is said that a good protocol of chemotherapy, most patients survive more than a year. Around 25% of feline patients may survive 2 years.

This article is purely informative. AnimalWised does not have the authority to prescribe any veterinary treatment or create a diagnosis. We invite you to take your pet to the veterinarian if they are suffering from any condition or pain.

If you want to read similar articles to My Cat's Lymphocytes are High, we recommend you visit our Other health problems category.


1. Campbell, M. W., Hess, P. R., & Williams, L. E. (2013). Chronic Lymphocytic Leukemia in Cats: 18 Cases (200-2010). Veterinary and Comparatve Oncology, 11(4), 256-264.

2. Tomiyasu, H., et al. (2018). Clinical and Cinicopathological Characteristics of Acute Lymphoblastic Leukaemia in Six Cats. Journal of Small Animal Practice, 59(12), 742-746.

3. Graf, R., et al. (2016). Swiss Feline Cancer Registry 1965–2008: the Influence of Sex, Breed and Age on Tumour Types and Tumour Locations. Journal of Comparative Pathology, 154(2-3), 195-210.

4. Argyle, D. J., & Pecceu, E. (2016). Canine and Feline Lymphoma: Challenges and Opportunities for Creating a Paradigm Shift. Veterinary and Comparative Oncology, 14(S1), 1-7.

5. Milner, R. J., et al. (2005). Response Rates and Survival Times for Cats with Lymphoma Treated with the University of Wisconsin-Madison Chemotherapy Protocol: 38 Cases (1996-2003). Journal of the American Veterinary Medical Association, 227(7), 1118-1122.


1. Nelson, R. W, & Couto, C. G. (2013). Small Animal Internal Medicine. Mosby.

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My Cat's Lymphocytes are High