What is a High White Blood Cell Count in Cats? Causes, Symptoms, and Treatments of This Condition

A Cat Laying On The Floor With His Paw Raised
expert or vet photo
vet verified PetCareRx Staff Veterinarian DVM

White blood cells fight off infections in your cat's body. If your cat has a high white blood cell count, that is a clear sign that something is wrong.

Running periodic complete blood counts on your cat may be one of the best things you can do for their overall health. After all, a high white blood cell count in cats could point to a potassium deficiency or even cancer.

A complete blood count determines the number and types of blood cells present, specifically red blood cells, white blood cells, and platelets. A normal white blood cell count in cats typically ranges from 4,900 to 20,000 per microliter of blood. However, that “normal” range could vary depending on the age of the cat.

White blood cells, also known as leukocytes, defend the body against viruses, bacteria, and fungi. Your cat’s blood contains a militia of white blood cells known as the differential, which take the form of neutrophils, eosinophils, basophils, lymphocytes, and monocytes.

  • Neutrophils and eosinophils, which are produced in the cat’s bone marrow, are released into the bloodstream to destroy bacteria.
  • Basophils are also produced in the bone marrow, but researchers aren’t entirely clear as to their main purpose.
  • Lymphocytes are produced in the cat's lymph nodes and spleen.
  • Monocytes are stored in the spleen and bone marrow.

Your cat doesn’t necessarily need to be exhibiting signs of an illness for your vet to recommend a complete blood count. Some vets like to run a count during wellness exams to determine a normal range for your cat or to monitor overall health.

Why Would a Cat Have a High Blood Cell Count?

  • Bacterial or fungal infections can cause neutrophil levels to increase.
  • Stress can cause neutrophil levels to increase.
  • Parasites, such as heartworm, can cause eosinophil and basophil levels to increase.
  • Allergic reactions can cause eosinophil levels to increase.
  • Autoimmune diseases with occurrences of inflammation can cause lymphocyte levels to increase.
  • Various types of cancer or viral infections can cause lymphocyte and monocyte levels to increase.
  • Kidney failure can cause overall white blood cell levels to increase.
  • Potassium deficiencies can cause white blood cell levels to increase.
  • Medications, such as corticosteroids, can cause white blood cell levels to increase.

How You’ll Know if Something is Wrong

Symptoms are typically related to the cause of the high white blood cell count.

  • If the cause is an infection, symptoms will typically appear as fever, lack of appetite, moodiness, and fatigue. If the infection is external, there may be a rash, wound, or abscess.
  • If the cause is parasites, such as heartworm, symptoms will appear as coughing, rapid breathing, vomiting, fatigue, and weight loss.
  • If the cause is an autoimmune disease, the symptoms will vary depending on the disease. Swollen joints may be present, or hair loss and ulcers on the skin, as well as fever and fatigue.
  • If the cause is lymphoma or other types of cancer, symptoms will typically appear as swollen lymph nodes, tumors, weight loss, frequent urination, increased thirst, and fatigue.
  • If the cause is kidney failure, symptoms typically do not present themselves until considerable damage is done to the organ. When symptoms do appear, they appear as frequent urination, increased thirst, weight loss, fatigue, ulcers on the gums and tongue, vomiting, and diarrhea.
  • If the cause is allergies, symptoms will appear as continuous itching and scratching.
  • If the cause is a potassium deficiency, symptoms will appear as fatigue, weight loss, frequent urination, and vomiting.
  • If the cause is stress, symptoms will likely appear as moodiness, aggression, decrease in social interaction, and decreased appetite.

Treatment Options

If a complete blood count shows that your cat’s white blood cell levels are high, there are a number of treatments your vet may recommend tailored to the cause of the high blood cell count.

Infections, autoimmune diseases, lymphoma, kidney failure, allergies, potassium deficiencies, and stress will all be treated with the best option for your pet.

When it comes to heartworms, there are no products in the United States approved for their treatment in cats. That’s why preventative medications are so important. In most cases, cats fight off the infection on their own, but you should still see your vet.

As the condition is treated, the results of follow-up blood tests should show white blood cell counts leveling out to the recommended range.

Frequently Asked Questions

What does it mean when a cat's white blood cell count is high?

When a cat's white blood cell count is high, it typically indicates an active immune system response. Elevations in NEU, LYM, and MONO (neutrophils, lymphocytes, and monocytes) suggest the body is combating an infection or possibly dealing with cancer. These white blood cells play crucial roles in fighting pathogens and abnormal cells, so an increase in their numbers signals an ongoing battle within the body.

If EOS (eosinophils) are elevated, it may point toward allergic reactions or parasitic infestations. These cells are particularly involved in allergic responses and defense against parasites. When their levels rise, it could signify the presence of allergens or parasites triggering the immune system.

A high white blood cell count in a cat's blood test indicates heightened activity within the bloodstream, often due to inflammation or infection. This could range from a mild, acute infection to a more severe or chronic infectious disease. In rare cases, persistent eosinophils may indicate hypereosinophilic syndrome, a condition characterized by excessive eosinophil production. While these indicators are commonly found in cases of infection or inflammation, they may also occur in other conditions with similar symptoms.

Is a high white blood cell count life-threatening?

A high white blood cell count, known as leukocytosis, is typically a normal immune response and isn't inherently life-threatening. It often signifies that the body is actively combating infection or inflammation, essential for maintaining health. When detected through blood tests, elevated white cell counts indicate increased immune system activity within the bloodstream, suggesting the presence of pathogens or tissue damage.

However, while leukocytosis is usually a benign response, there are circumstances where a high white blood cell count could signal a more serious underlying condition, such as leukemia. Leukemia is a type of cancer characterized by the abnormal production of white blood cells in the bone marrow, leading to an excessive accumulation of these cells in the bloodstream. In such cases, the elevated white cell count may not effectively combat infection or inflammation and can impair normal immune function.

Moreover, persistent or significantly elevated white blood cell counts, especially with other symptoms, could indicate severe inflammation, chronic infections, or other infectious diseases. In rare instances, persistently elevated eosinophils may suggest hypereosinophilic syndrome, a potentially serious condition that requires medical attention.

While leukocytosis itself may not be life-threatening, the underlying cause of the elevated white blood cell count should be thoroughly investigated and addressed. Prompt medical evaluation, including further diagnostic tests and appropriate treatment, is essential for managing any potential underlying conditions.

What kind of infections can cause high white blood cells?

A high white blood cell count (WBC), detected through blood tests or blood work, can indicate various conditions, including infections and inflammatory diseases. It may suggest bacterial or viral infections, where the immune system responds by producing more white blood cells to combat the invading pathogens. Additionally, conditions like rheumatoid arthritis trigger chronic inflammation, increasing white blood cells as part of the immune response. Severe allergic reactions can prompt the body to release more white blood cells into the bloodstream, contributing to a high WBC count. In some cases, a high WBC count may indicate more serious conditions such as leukemia or Hodgkin's disease, where there's an abnormal proliferation of white blood cells. Moreover, any form of tissue damage, whether from burn injuries or surgical procedures, can provoke inflammation, prompting an increase in white blood cells as part of the healing process. A rare disorder called hypereosinophilic syndrome is characterized by excess eosinophils, a type of white blood cell, in the bloodstream. An increase in eosinophils can be detected through blood tests and may indicate this syndrome. A high white blood cell count can signify various health issues, ranging from common infections to more serious conditions like leukemia. Veterinary doctors can interpret these results with other symptoms and diagnostic tests to determine the underlying cause.

Can kidney disease cause high white blood cell count in cats?

Kidney disease in cats can lead to changes in blood cell counts and organ function, often assessed through various kidney function tests.

A high white blood cell count in cats indicates an infection or inflammation. While kidney disease might not directly cause a high white blood cell count, it can be associated with secondary infections or inflammatory processes, which can elevate the white blood cell count. For instance, cats with chronic kidney disease (CKD) are more susceptible to urinary tract infections, which could cause an increase in white blood cell count.

On the other hand, a low red blood cell count (anemia) is commonly observed in cats with kidney failure. The kidneys produce erythropoietin, a hormone essential for red blood cell production. When kidney function declines, erythropoietin production decreases, leading to anemia.

Symmetric dimethylarginine (SDMA) is an important biomarker used to detect kidney disease in cats early. SDMA levels increase when there is reduced kidney function, often before other indicators, such as creatinine, show abnormal results. Monitoring SDMA levels can provide early insights into declining kidney function and help manage the condition more effectively.

Additional kidney function tests include measurements of blood urea nitrogen (BUN) and creatinine levels, which are commonly used to assess kidney function. High levels of these substances in the blood indicate reduced kidney function.

It's also necessary to monitor alanine aminotransferase (ALT) levels, primarily indicative of liver function but can also be affected by other organ functions, including the kidneys. Elevated ALT levels can suggest organ stress or damage, and when combined with other kidney function test results, they can provide a more comprehensive understanding of a cat's overall organ function.

How do you treat high white blood cells in cats?

Steroids like prednisone or prednisolone are commonly administered to cats to reduce inflammation and suppress the immune response. These steroids help stop the production of eosinophils, a type of white blood cell often elevated in inflammatory conditions. Additionally, hydroxyurea may be used for cats diagnosed with certain types of cancers, such as lymphoid leukemia. This antineoplastic drug helps to control the overproduction of white blood cells by inhibiting the growth of cancer cells.

If the high white blood cell count is due to an infection, appropriate antibiotics or antiviral medications will be prescribed, particularly if the cat has tested positive for conditions like feline leukemia virus (FeLV) or feline immunodeficiency virus (FIV). 

In severe cases of anemia, a blood transfusion might be necessary to stabilize the cat. If the cat is experiencing respiratory distress, oxygen therapy can be provided to ensure adequate oxygen levels in the blood. These interventions can help support the cat’s overall health while treating the underlying cause.

A bone marrow biopsy can help determine the production of blood cells in the bone marrow, providing insights into potential issues. Imaging studies, such as X-rays, can help identify any underlying problems, including tumors or organ infections. 

To track the cat's progress, blood cell counts and kidney function tests, including symmetric dimethylarginine (SDMA), blood urea nitrogen (BUN), and creatinine levels, must be regularly monitored. Screening for other conditions, like diabetes mellitus, which can complicate treatment and management, is also necessary.

More on Cat Health

Caring for a Cat With Cancer at Home
Food to Treat Kidney Disease in Cats and Dogs
Antibiotics for Cats

This information is for informational purposes only and is not meant as a substitute for the professional advice of, or diagnosis or treatment by, your veterinarian with respect to your pet. It has, however, been verified by a licensed veterinarian for accuracy.

Was this article helpful?
General Allergies Kidney Failure Heartworm

You May Also Like